514 research outputs found
Role of toll-like receptor 2 (TLR2) in neutrophil activation: GM-CSF enhances TLR2 expression and TLR2-mediated interleukin 8 responses in neutrophils
In vitro studies as well as clinical trials indicate that the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) enhance the ability of neutrophils (polymorphonuclear leukocytes) to eliminate microbial organisms. Toll-like receptor (TLR) proteins, homologs of the Drosophila protein Toll, have been found on the surface of mammalian cells and are important in the responses of macrophages to bacterial, viral, and fungal antigens. TLR4 is critical for the response to lipopolysaccharide (LPS) of gram-negative bacteria, while TLR2 is important for response to gram-positive bacteria, bacterial peptides, and yeast zymosan. We demonstrate that TLR2, but very little TLR4, is present on the surface of human neutrophils. In addition we demonstrate that GM-CSF and G-CSF dramatically up-regulate TLR2 and CD14 surface expression. GM-CSF treatment also up-regulates TLR2 and CD14 mRNA levels in neutrophils. In addition to increasing receptor expression, GM-CSF treatment enhanced the interleukin 8 (IL-8) secretion and superoxide priming responses of neutrophils to stimulation with TLR2 ligands, including zymosan, peptidoglycan, and lipoarabinomannan. The human monocyte response to crude bacterial LPS is composed of a TLR4-specific response to the pure LPS component and a TLR2-dependent response to associated lipopeptides. The removal of TLR2 lipopeptide components from LPS by phenol re-extraction substantially reduced both the IL-8 and superoxide response of the stimulated neutrophils, indicating that, unlike monocytes, the neutrophil response is preferentially directed to TLR2 ligands. Thus, our studies demonstrate that GM-CSF dramatically enhances the functional response of neutrophils to TLR2 ligands, including LPS-associated lipopeptides
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BIOTIGER, A NATURAL MICROBIAL PRODUCT FOR ENHANCED HYDROCARBON RECOVERY FROM OIL SANDS.
BioTiger{trademark} is a unique microbial consortia that resulted from over 8 years of extensive microbiology screening and characterization of samples collected from a century-old Polish waste lagoon. BioTiger{trademark} shows rapid and complete degradation of aliphatic and aromatic hydrocarbons, produces novel surfactants, is tolerant of both chemical and metal toxicity and shows good activity at temperature and pH extremes. Although originally developed and used by the U.S. Department of Energy for bioremediation of oil-contaminated soils, recent efforts have proven that BioTiger{trademark} can also be used to increase hydrocarbon recovery from oil sands. This enhanced ex situ oil recovery process utilizes BioTiger{trademark} to optimize bitumen separation. A floatation test protocol with oil sands from Ft. McMurray, Canada was used for the BioTiger{trademark} evaluation. A comparison of hot water extraction/floatation test of the oil sands performed with BioTiger{trademark} demonstrated a 50% improvement in separation as measured by gravimetric analysis in 4 h and a five-fold increase at 25 hr. Since BioTiger{trademark} performs well at high temperatures and process engineering can enhance and sustain metabolic activity, it can be applied to enhance recovery of hydrocarbons from oil sands or other complex recalcitrant matrices
The Life and Death of Dense Molecular Clumps in the Large Magellanic Cloud
We report the results of a high spatial (parsec) resolution HCO+ (J = 1-0)
and HCN (J = 1-0) emission survey toward the giant molecular clouds of the star
formation regions N105, N113, N159, and N44 in the Large Magellanic Cloud. The
HCO+ and HCN observations at 89.2 and 88.6 GHz, respectively, were conducted in
the compact configuration of the Australia Telescope Compact Array. The
emission is imaged into individual clumps with masses between 10^2 and 10^4
solar masses and radii of <1 pc to ~2 pc. Many of the clumps are coincident
with indicators of current massive star formation, indicating that many of the
clumps are associated with deeply-embedded forming stars and star clusters. We
find that massive YSO-bearing clumps tend to be larger (>1 pc), more massive (M
> 10^3 solar masses), and have higher surface densities (~1 g cm^-2), while
clumps without signs of star formation are smaller (<1 pc), less massive (M <
10^3 solar masses), and have lower surface densities (~0.1 g cm^-2). The dearth
of massive (M >10^3 solar masses) clumps not bearing massive YSOs suggests the
onset of star formation occurs rapidly once the clump has attained physical
properties favorable to massive star formation. Using a large sample of LMC
massive YSO mid-IR spectra, we estimate that ~2/3 of the massive YSOs for which
there are Spitzer mid-IR spectra are no longer located in molecular clumps; we
estimate that these young stars/clusters have destroyed their natal clumps on a
time scale of at least 3 x 10^{5}$ yrs.Comment: Accepted to ApJ 3-19-201
Simulating chemistry efficiently on fault-tolerant quantum computers
Quantum computers can in principle simulate quantum physics exponentially
faster than their classical counterparts, but some technical hurdles remain.
Here we consider methods to make proposed chemical simulation algorithms
computationally fast on fault-tolerant quantum computers in the circuit model.
Fault tolerance constrains the choice of available gates, so that arbitrary
gates required for a simulation algorithm must be constructed from sequences of
fundamental operations. We examine techniques for constructing arbitrary gates
which perform substantially faster than circuits based on the conventional
Solovay-Kitaev algorithm [C.M. Dawson and M.A. Nielsen, \emph{Quantum Inf.
Comput.}, \textbf{6}:81, 2006]. For a given approximation error ,
arbitrary single-qubit gates can be produced fault-tolerantly and using a
limited set of gates in time which is or ; with sufficient parallel preparation of ancillas, constant average
depth is possible using a method we call programmable ancilla rotations.
Moreover, we construct and analyze efficient implementations of first- and
second-quantized simulation algorithms using the fault-tolerant arbitrary gates
and other techniques, such as implementing various subroutines in constant
time. A specific example we analyze is the ground-state energy calculation for
Lithium hydride.Comment: 33 pages, 18 figure
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OFFGAS GENERATION FROM THE DISPOSITION OF SCRAP PLUTONIUM BY VITRIFICATION SIMULANT TESTS
The Department of Energy Office of Environmental Management is supporting R&D for the conceptual design of the Plutonium Disposition Project at the Savannah River Site in Aiken, SC to reduce the attractiveness of plutonium scrap by fabricating a durable plutonium oxide glass form and immobilizing this form within the high-level waste glass prepared in the Defense Waste Processing Facility. A glass formulation was developed that is capable of incorporating large amounts of actinides as well as accommodating many impurities that may be associated with impure Pu feed streams. The basis for the glass formulation was derived from commercial glasses that had high lanthanide loadings. A development effort led to a Lanthanide BoroSilicate (LaBS) glass that accommodated significant quantities of actinides, tolerated impurities associated with the actinide feed streams and could be processed using established melter technologies. A Cylindrical Induction Melter (CIM) was used for vitrification of the Pu LaBS glass. Induction melting for the immobilization of americium and curium (Am/Cm) in a glass matrix was first demonstrated in 1997. The induction melting system was developed to vitrify a non-radioactive Am/Cm simulant combined with a glass frit. Most of the development of the melter itself was completed as part of that work. This same melter system used for Am/Cm was used for the current work. The CIM system used consisted of a 5 inch (12.7 cm) diameter inductively heated platinum-rhodium (Pt-Rh) containment vessel with a control system and offgas characterization. Scrap plutonium can contain numerous impurities including significant amounts of chlorides, fluorides, sodium, potassium, lead, gallium, chromium, and nickel. Smaller amounts of additional elements can also be present. The amount of chlorides present is unusually high for a melter feed. In commercial applications there is no reason to have chloride at such high concentrations. Because the melter operates at 1400-1475 C, many of the impurities present are extremely volatile. An alternative being considered is to pre-treat the impure PuO{sub 2} by water washing to remove the soluble salts, which would significantly reduce the melter emissions. The disadvantage of the washing alternative is the criticality concerns of using water with plutonium. In this paper, the testing that has been conducted at the Savannah River National Laboratory (SRNL) to demonstrate induction melting of impure plutonium simulants will be described. The work described concentrates on quantification of the gaseous and particulate emissions from the induction melter. The Pt-Rh melter vessel is a cylinder with a conical bottom and a tubular drain as shown in Figure 1. A 5-inch (12.7 cm) diameter CIM was used for all of the emissions tests. A 6-inch (15.24 cm) diameter CIM, which is the size of the full-scale melter, has since been constructed for further testing. The 5-inch CIM is heated by three induction coils: one for the 5 inch cylinder, one for the conical section, and one for the 1/4-inch (6.35 mm) drain tube. The 6-inch CIM is similar except the cylinder heater extends lower and also heats the cone. The induction heating system is manufactured by Ameritherm{trademark}. The heating system is controlled by a PC to maintain a specific heat up profile and then maintain a constant energy input that maintains a constant temperature. The CIM is operated in batch mode where the plutonium simulant and the glass-forming frit are first thoroughly mixed in an attrittor mill, then added to the melter. Hafnium oxide (HfO{sub 2}) is used as a simulant for the radioactive PuO{sub 2}. The melter is heated until the mixture begins to melt at about 1100 C, then completely melts at about 1400-1450 C. This temperature is maintained for about three hours. While the temperature is maintained at {approx} 1400 C, an air bubbler is normally used to promote mixing of the glass-forming frit and the waste simulant
MAMBO Mapping of Spitzer c2d Small Clouds and Cores
AIMS: To study the structure of nearby (< 500 pc) dense starless and
star-forming cores with the particular goal to identify and understand
evolutionary trends in core properties, and to explore the nature of Very Low
Luminosity Objects (< 0.1 L_sun; VeLLOs). METHODS: Using the MAMBO bolometer
array, we create maps unusually sensitive to faint (few mJy per beam) extended
(approx. 5 arcmin) thermal dust continuum emission at 1.2 mm wavelength.
Complementary information on embedded stars is obtained from Spitzer, IRAS, and
2MASS. RESULTS: Our maps are very rich in structure, and we characterize
extended emission features (``subcores'') and compact intensity peaks in our
data separately to pay attention to this complexity. We derive, e.g., sizes,
masses, and aspect ratios for the subcores, as well as column densities and
related properties for the peaks. Combination with archival infrared data then
enables the derivation of bolometric luminosities and temperatures, as well as
envelope masses, for the young embedded stars. CONCLUSIONS: (abridged) Starless
and star-forming cores occupy the same parameter space in many core properties;
a picture of dense core evolution in which any dense core begins to actively
form stars once it exceeds some fixed limit in, e.g., mass, density, or both,
is inconsistent with our data. Comparison of various evolutionary indicators
for young stellar objects in our sample (e.g., bolometric temperatures) reveals
inconsistencies between some of them, possibly suggesting a revision of some of
these indicators.Comment: Accepted to A&A. In total 46 pages, with 20 pages of tables, figures,
and appendices. High-resolution version of this article at
https://www.xythosondemand.com/home/harvard_iic/Users/jkauffma/Public/mambo_spitzer.pd
The Dust Properties of Two Hot R Coronae Borealis Stars and a Wolf-Rayet Central Star of a Planetary Nebula: in Search of a Possible Link
We present new Spitzer/IRS spectra of two hot R Coronae Borealis (RCB) stars,
one in the Galaxy,V348 Sgr, and one lying in the LMC, HV 2671. These two
objects may constitute a link between the RCB stars and the late Wolf-Rayet
([WCL]) class of central stars of planetary nebula (CSPNe) such as CPD -56 8032
that has little or no hydrogen in their atmospheres. HV 2671 and V348 Sgr are
members of a rare subclass that has significantly higher effective temperatures
than most RCB stars, but sharing the traits of hydrogen deficiency and dust
formation that define the cooler RCB stars. The [WC] CSPNe star, CPD -56 8032,
displays evidence for dual-dust chemistry showing both PAHs and crystalline
silicates in its mid-IR spectrum. HV 2671 shows strong PAH emission but shows
no sign of having crystalline silicates. The spectrum of V348 Sgr is very
different from those of CPD -56 8032 and HV 2671. The PAH emission seen
strongly in the other two stars is not present. Instead, the spectrum is
dominated by a broad emission centered at about 8.2 micron. The mid-IR spectrum
of CPD -56 8032 shows emission features that may be associated with C60. The
other two stars do not show evidence for C60. HV 2671 has also been detected by
Herschel/PACS and SPIRE. V348 Sgr and CPD -56 8032 have been detected by
AKARI/FIS. These data were combined with Spitzer, IRAS, 2MASS and other
photometry to produce their spectral energy distributions from the visible to
the far-IR. Monte Carlo radiative transfer modeling was used to study the
circumstellar dust around these stars. HV 2671 and CPD -56 8032 require both a
flared inner disk with warm dust and an extended diffuse envelope with cold
dust to to fit their SEDs. The SED of V348 Sgr can be fit with a much smaller
disk and envelope.Comment: 20 pages, 5 figures, accepted for publication in The Astronomical
Journa
Initial characteristics of RbcX proteins from Arabidopsis thaliana
Form I of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) is composed of eight large (RbcL) and eight small (RbcS) subunits. Assembly of these subunits into a functional holoenzyme requires the assistance of additional assembly factors. One such factor is RbcX, which has been demonstrated to act as a chaperone in the assembly of most cyanobacterial Rubisco complexes expressed in heterologous system established in Escherichia coli cells. Analysis of Arabidopsis thaliana genomic sequence revealed the presence of two genes encoding putative homologues of cyanobacterial RbcX protein: AtRbcX1 (At4G04330) and AtRbcX2 (At5G19855). In general, both RbcX homologues seem to have the same function which is chaperone activity during Rubisco biogenesis. However, detailed analysis revealed slight differences between them. AtRbcX2 is localized in the stromal fraction of chloroplasts whereas AtRbcX1 was found in the insoluble fraction corresponding with thylakoid membranes. Search for putative “partners” using mass spectrometry analysis suggested that apart from binding to RbcL, AtRbcX1 may also interact with β subunit of chloroplast ATP synthase. Quantitative RT-PCR analysis of AtRbcX1 and AtRbcX2 expression under various stress conditions indicated that AtRbcX2 is transcribed at a relatively stable level, while the transcription level of AtRbcX1 varies significantly. In addition, we present the attempts to elucidate the secondary structure of AtRbcX proteins using CD spectroscopy. Presented results are the first known approach to elucidate the role of RbcX proteins in Rubisco assembly in higher plants
New Insights Into Legacy Phosphorus From Fractionation of Streambed Sediment
Streambed and lake sediment was studied in Savjaan, a eutrophic mesoscale catchment (722 km(2)) in central Sweden. Triplicate sediment cores from five lakes and nine streams, ranging from headwater to fourth order, were sampled. The sediment was analyzed with a sequential extraction method, where six different phosphorus (P) fractions were measured. The results showed that streambed sediments store considerable amounts of P and in some cases have comparable P contents (g/kg DW) to lake sediment. Land use, soil type, and drainage area (location in the catchment) had a significant effect on the different P fractions found in surficial sediments. Sediment from lakes and forested headwater streams generally had high proportions of organic P and iron bound P. In larger streams located in agricultural areas on clay soils closer to the catchment outlet, with dense sediment and a relatively low proportion of organic matter, P was to a larger extent bound to calcium. Streambed sediment may be an important catchment scale P store and should be considered when modeling catchment P dynamics. The large stores of streambed legacy P should also be considered when performing ditch maintenance to avoid unnecessary mobilization of bioavailable P
A Multiwavelength View of Star Formation in Interacting Galaxies in the Pavo Group
We combine Spitzer IRAC mid-infrared (MIR) and Chandra X-ray observations of
the dominant galaxies NGC6872 and NGC6876 in the Pavo group with archival
optical and HI data to study interaction-induced star formation. In spiral
galaxy NGC6872, 8.0 and 5.8 micron nonstellar emission having colors consistent
with polycyclic aromatic hydrocarbons (PAHs) is concentrated in clumps in three
regions: in a 5 kpc radius outer ring about the center of the spiral galaxy, in
a bridge of emission connecting NGC6872's northern spiral arm to IC4970, and
along the full extent of NGC6872's tidal arms. PAH emission is correlated with
young star clusters and dense HI regions. We find no strong differences in the
MIR colors of star-forming regions in the spiral galaxy NGC6872 as a function
of position relative to the tidally interacting companion galaxy IC4970. We
find 11 very luminous X-ray sources (>~ (0.5 - 5) x 10^{39} ergs/s) clustered
to the southwest in NGC6872, near bright star-forming regions. In NGC6872's
tidal features, young star clusters form at the boundaries of diffuse X-ray
gas, suggesting that stars form as gas stripped by the interactions cools. The
nucleus of NGC6872 is a weak X-ray point source (0.5-8 keV luminosity of 8.5 x
10^{39} ergs/s), but there is little evidence in the inner 1 kpc of NGC6872 for
PAH emission from recent star formation or nuclear activity. However, a 4 kpc
`stream', leading from the outer ring of NGC6872 to the nucleus, may signal
transport of interstellar matter into NGC6872's nuclear region. Nonstellar
emission, consistent with PAH emission, is also found in the central region of
elliptical galaxy NGC6877, companion to dominant Pavo group elliptical NGC6876.
However, in the central region of NGC6876, the dust emission is more likely due
to silicate emission from old AGB stars.Comment: 17 pages, 24 figures, ApJ, accepte
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