144 research outputs found
Determining the feasibility of installing individual gas and electric meters in military family housing units.
Rapid and effective oxidative pretreatment of woody biomass at mild reaction conditions and low oxidant loadings
BACKGROUND: One route for producing cellulosic biofuels is by the fermentation of lignocellulose-derived sugars generated from a pretreatment that can be effectively coupled with an enzymatic hydrolysis of the plant cell wall. While woody biomass exhibits a number of positive agronomic and logistical attributes, these feedstocks are significantly more recalcitrant to chemical pretreatments than herbaceous feedstocks, requiring higher chemical and energy inputs to achieve high sugar yields from enzymatic hydrolysis. We previously discovered that alkaline hydrogen peroxide (AHP) pretreatment catalyzed by copper(II) 2,2Î-bipyridine complexes significantly improves subsequent enzymatic glucose and xylose release from hybrid poplar heartwood and sapwood relative to uncatalyzed AHP pretreatment at modest reaction conditions (room temperature and atmospheric pressure). In the present work, the reaction conditions for this catalyzed AHP pretreatment were investigated in more detail with the aim of better characterizing the relationship between pretreatment conditions and subsequent enzymatic sugar release. RESULTS: We found that for a wide range of pretreatment conditions, the catalyzed pretreatment resulted in significantly higher glucose and xylose enzymatic hydrolysis yields (as high as 80% for both glucose and xylose) relative to uncatalyzed pretreatment (up to 40% for glucose and 50% for xylose). We identified that the extent of improvement in glucan and xylan yield using this catalyzed pretreatment approach was a function of pretreatment conditions that included H(2)O(2) loading on biomass, catalyst concentration, solids concentration, and pretreatment duration. Based on these results, several important improvements in pretreatment and hydrolysis conditions were identified that may have a positive economic impact for a process employing a catalyzed oxidative pretreatment. These improvements include identifying that: (1) substantially lower H(2)O(2) loadings can be used that may result in up to a 50-65% decrease in H(2)O(2) application (from 100 mg H(2)O(2)/g biomass to 35â50 mg/g) with only minor losses in glucose and xylose yield, (2) a 60% decrease in the catalyst concentration from 5.0 mM to 2.0 mM (corresponding to a catalyst loading of 25 ÎŒmol/g biomass to 10 ÎŒmol/g biomass) can be achieved without a subsequent loss in glucose yield, (3) an order of magnitude improvement in the time required for pretreatment (minutes versus hours or days) can be realized using the catalyzed pretreatment approach, and (4) enzyme dosage can be reduced to less than 30 mg protein/g glucan and potentially further with only minor losses in glucose and xylose yields. In addition, we established that the reaction rate is improved in both catalyzed and uncatalyzed AHP pretreatment by increased solids concentrations. CONCLUSIONS: This work explored the relationship between reaction conditions impacting a catalyzed oxidative pretreatment of woody biomass and identified that significant decreases in the H(2)O(2), catalyst, and enzyme loading on the biomass as well as decreases in the pretreatment time could be realized with only minor losses in the subsequent sugar released enzymatically. Together these changes would have positive implications for the economics of a process based on this pretreatment approach
Identification of Epigenetic Signature Associated With Alpha Thalassemia/Mental Retardation X-linked Syndrome
BACKGROUND: Alpha thalassemia/mental retardation X-linked syndrome (ATR-X) is caused by a mutation at the chromatin regulator gene
RESULTS: We performed genome-wide DNA methylation assessment of the peripheral blood samples from 18 patients with ATR-X and compared it to 210 controls. We demonstrated the evidence of a unique and highly specific DNA methylation epi-signature in the peripheral blood of ATRX patients, which was corroborated by targeted bisulfite sequencing experiments. Although genomically represented, differentially methylated regions showed evidence of preferential clustering in pericentromeric and telometric chromosomal regions, areas where ATRX has multiple functions related to maintenance of heterochromatin and genomic integrity.
CONCLUSION: Most significant methylation changes in the 14 genomic loci provide a unique epigenetic signature for this syndrome that may be used as a highly sensitive and specific diagnostic biomarker to support the diagnosis of ATR-X, particularly in patients with phenotypic complexity and in patients wit
1985: Abilene Christian College Bible Lectures - Full Text
WHAT THE CHURCH NEEDS TO HEAR
Being the Abilene Christian University Annual Bible Lectures 1985
Published by A-C-U PRESS
ACU Station Abilene, Texas 7969
First-year Results of Broadband Spectroscopy of the Brightest Fermi-GBM Gamma-Ray Bursts
We present here our results of the temporal and spectral analysis of a sample
of 52 bright and hard gamma-ray bursts (GRBs) observed with the Fermi Gamma-ray
Burst Monitor (GBM) during its first year of operation (July 2008-July 2009).
Our sample was selected from a total of 253 GBM GRBs based on each event peak
count rate measured between 0.2 and 40MeV. The final sample comprised 34 long
and 18 short GRBs. These numbers show that the GBM sample contains a much
larger fraction of short GRBs, than the CGRO/BATSE data set, which we explain
as the result of our (different) selection criteria and the improved GBM
trigger algorithms, which favor collection of short, bright GRBs over BATSE. A
first by-product of our selection methodology is the determination of a
detection threshold from the GBM data alone, above which GRBs most likely will
be detected in the MeV/GeV range with the Large Area Telescope (LAT) onboard
Fermi. This predictor will be very useful for future multiwavelength GRB follow
ups with ground and space based observatories. Further we have estimated the
burst durations up to 10MeV and for the first time expanded the duration-energy
relationship in the GRB light curves to high energies. We confirm that GRB
durations decline with energy as a power law with index approximately -0.4, as
was found earlier with the BATSE data and we also notice evidence of a possible
cutoff or break at higher energies. Finally, we performed time-integrated
spectral analysis of all 52 bursts and compared their spectral parameters with
those obtained with the larger data sample of the BATSE data. We find that the
two parameter data sets are similar and confirm that short GRBs are in general
harder than longer ones.Comment: 40 pages, 11 figures, 3 tables, Submitted to Ap
Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B
Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor (GBM) find
that the spectrum is dominated by the typical Band functional form, which is
usually taken to represent a non-thermal emission component, but also includes
a statistically highly significant thermal spectral contribution. The
simultaneous observation of the thermal and non-thermal components allows us to
confidently identify the two emission components. The fact that these seem to
vary independently favors the idea that the thermal component is of
photospheric origin while the dominant non-thermal emission occurs at larger
radii. Our results imply either a very high efficiency for the non-thermal
process, or a very small size of the region at the base of the flow, both quite
challenging for the standard fireball model. These problems are resolved if the
jet is initially highly magnetized and has a substantial Poynting flux.Comment: 6 pages, 3 figures, 1 table, Accepted for publication in the
Astrophysical Journal Letters November, 23 2010 (Submitted October, 20 2010
Temporal Deconvolution study of Long and Short Gamma-Ray Burst Light curves
The light curves of Gamma-Ray Bursts (GRBs) are believed to result from
internal shocks reflecting the activity of the GRB central engine. Their
temporal deconvolution can reveal potential differences in the properties of
the central engines in the two populations of GRBs which are believed to
originate from the deaths of massive stars (long) and from mergers of compact
objects (short). We present here the results of the temporal analysis of 42
GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray
Space Telescope. We deconvolved the profiles into pulses, which we fit with
lognormal functions. The distributions of the pulse shape parameters and
intervals between neighboring pulses are distinct for both burst types and also
fit with lognormal functions. We have studied the evolution of these parameters
in different energy bands and found that they differ between long and short
bursts. We discuss the implications of the differences in the temporal
properties of long and short bursts within the framework of the internal shock
model for GRB prompt emission.Comment: 38 pages, 11 figure
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