5,301 research outputs found
Improvement of rheological and functional properties of milk protein concentrate by hydrodynamic cavitation
Spray drying at higher solids concentrations improves drying efficiency, and reduces the overall energy cost of milk powder production. As the performance of the evaporator prior to spray drying is limited by viscosity, several methods can be employed to reduce feed viscosity such as thermal pre-treatment or ultrasound. The method employed in this study was hydrodynamic cavitation (HC) on milk protein concentrate (MPC80). Rheological properties of the protein milk were observed to improve, with a reduction in viscosity by 20% and 56% upon the application of a cavitation rotor speed of 25 Hz and 50 Hz, respectively, due to the breakdown in protein gel structure and hence a decrease in the elastic modulus of the proteins. While HC did not adversely affect solubility, with the powders having on average a solubility of 97.5% at a reconstitution temperature of 50 °C, both bulk and tapped density increased when the emulsion was subjected to HC, owing to a reduction in particle size. This study therefore suggests the potential of using HC for a more efficient drying of high solids milk, while maintaining and/or improving the physicochemical properties of powders
One thousand days of SN 2015bn: HST imaging shows a light curve flattening consistent with magnetar predictions
We present the first observations of a Type I superluminous supernova (SLSN)
at days after maximum light. We observed SN 2015bn using the
Hubble Space Telescope Advanced Camera for Surveys in the F475W, F625W and
F775W filters at 721 days and 1068 days. SN 2015bn is clearly detected and
resolved from its compact host, allowing reliable photometry. A galaxy template
constructed from these data further enables us to isolate the SLSN flux in deep
ground-based imaging. We measure a light curve decline rate at days of
mag (100 d), much shallower than the earlier evolution,
and slower than previous SLSNe (at any phase) or the decay rate of Co.
Neither additional radioactive isotopes nor a light echo can consistently
account for the slow decline. A spectrum at 1083 days shows the same [O I] and
[Ca II] lines as seen at days, with no new features to indicate
strong circumstellar interaction. Radio limits with the Very Large Array rule
out an extended wind for mass-loss rates M yr (where is the wind velocity in
units of 10 km s). The optical light curve is consistent with , which we show is expected for magnetar spin-down with inefficient
trapping; furthermore, the evolution matches predictions from earlier magnetar
model fits. The opacity to magnetar radiation is constrained at
cm g, consistent with photon-matter pair-production over a broad
GeV-TeV range. This suggests the magnetar spectral energy distribution,
and hence the 'missing energy' leaking from the ejecta, may peak in this range.Comment: Accepted for publication in ApJL, updated to match accepted versio
Spitzer Space Telescope Infrared Observations of the Binary Neutron Star Merger GW170817
We present Spitzer Space Telescope 3.6 and 4.5 micron observations of the
binary neutron star merger GW170817 at 43, 74, and 264 days post-merger. Using
the final observation as a template, we uncover a source at the position of
GW170817 at 4.5 micron with a brightness of 22.9+/-0.3 AB mag at 43 days and
23.8+/-0.3 AB mag at 74 days (the uncertainty is dominated by systematics from
the image subtraction); no obvious source is detected at 3.6 micron to a
3-sigma limit of >23.3 AB mag in both epochs. The measured brightness is dimmer
by a factor of about 2-3 times compared to our previously published kilonova
model, which is based on UV, optical, and near-IR data at <30 days. However,
the observed fading rate and color (m_{3.6}-m_{4.5}> 0 AB mag) are consistent
with our model. We suggest that the discrepancy is likely due to a transition
to the nebular phase, or a reduced thermalization efficiency at such late time.
Using the Spitzer data as a guide, we briefly discuss the prospects of
observing future binary neutron star mergers with Spitzer (in LIGO/Virgo
Observing Run 3) and the James Webb Space Telescope (in LIGO/Virgo Observing
Run 4 and beyond).Comment: 6 pages, 2 figures, submitted to ApJ
Thermodynamic formalism for contracting Lorenz flows
We study the expansion properties of the contracting Lorenz flow introduced
by Rovella via thermodynamic formalism. Specifically, we prove the existence of
an equilibrium state for the natural potential for the contracting Lorenz flow and for in an interval
containing . We also analyse the Lyapunov spectrum of the flow in terms
of the pressure
Bkm sequences from the human X chromosome contain large clusters of GATA/GACA repeats
In order to determine whether the regional localizations of Bkm repeats detected on the human X chromosome consisted of typical GATA/GACA repeats, clones were isolated, mapped, and sequenced. Nine Bkm-hybridizing clones from Kunkel's fluorescent-activated, cell-sorted X-chromosome library were all unique. Five were mapped in detail with restriction enzymes and the Bkm-hybridizing segments were localized. Confirmation of X chromosomal homology was obtained for 2 of the clones and Bkm segments from these 2 clones were sequenced. Seventeen contiguous GATA repeats were found in each clone and the overall repeat arrangement showed relatively few differences from previously sequenced Bkm sequences. These are the first sequences of human Bkm repeats. The results, when compared with previously published results, suggest that there may be significant differences between the organization of Bkm repeats on the human X and on the human Y chromosome.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66402/1/j.1469-1809.1988.tb01094.x.pd
Influence of HiPIMS pulse widths on the deposition behaviour and properties of CuAgZr compositionally graded films
In this work, the influence of different pulse widths (25, 50 and 100 ÎŒs) during high power impulse magnetron sputtering (HiPIMS) of copper, silver and zirconium was investigated in terms of plasma properties and properties of combinatorial composition gradient CuAgZr film libraries. In situ plasma diagnostics via optical emission spectroscopy (OES), time-of-flight mass spectrometry (TOFMS), and modified quartz crystal microbalance (m-QCM), followed by film ex situ X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations allowed to determine the effect of deposition parameters on the thin films' microstructural changes. Changing the pulse width, while keeping the duty cycle constant, modified the discharge composition in the target region and the ionised fraction of the sputtered species in the substrate region. The maximum Cu ionised fraction (19 %) was found for 50 ÎŒs, resulting in compact and smooth morphology for Cu-rich films, whereas short 25 ÎŒs pulses provided porous columnar films with rough surfaces, as the result from Ar+ bombardment. For Ag-rich films, Ag segregation allowed the deposition of dense layers, regardless of the used pulse width.
Furthermore, low Ag (<10 at.%) CuAgZr films produced via HiPIMS and direct-current magnetron sputtering (DCMS) were compared in terms of structural and mechanical property changes as a function of Zr contents. For the studied chemical composition range, a linear relationship between Zr content, XRD phase shift and mechanical properties was observed for HiPIMS films, in contrast to DCMS's more abrupt transitions. An increase in hardness and elastic modulus (up to 44 % and 22 %, respectively) was found for the HiPIMS films compared to DCMS ones. The obtained results highlight HiPIMS's flexibility in providing a wide range of tailoring possibilities to meet specific application requirements, such as crystalline microstructure, density and associated mechanical properties
The Binary Neutron Star event LIGO/VIRGO GW170817 a hundred and sixty days after merger: synchrotron emission across the electromagnetic spectrum
We report deep Chandra, HST and VLA observations of the binary neutron star
event GW170817 at d after merger. These observations show that GW170817
has been steadily brightening with time and might have now reached its peak,
and constrain the emission process as non-thermal synchrotron emission where
the cooling frequency is above the X-ray band and the synchrotron
frequency is below the radio band. The very simple power-law spectrum
extending for eight orders of magnitude in frequency enables the most precise
measurement of the index of the distribution of non-thermal relativistic
electrons accelerated by a shock launched by a
NS-NS merger to date. We find , which indicates that radiation
from ejecta with dominates the observed emission. While
constraining the nature of the emission process, these observations do
\emph{not} constrain the nature of the relativistic ejecta. We employ
simulations of explosive outflows launched in NS ejecta clouds to show that the
spectral and temporal evolution of the non-thermal emission from GW170817 is
consistent with both emission from radially stratified quasi-spherical ejecta
traveling at mildly relativistic speeds, \emph{and} emission from off-axis
collimated ejecta characterized by a narrow cone of ultra-relativistic material
with slower wings extending to larger angles. In the latter scenario, GW170817
harbored a normal SGRB directed away from our line of sight. Observations at
days are unlikely to settle the debate as in both scenarios the
observed emission is effectively dominated by radiation from mildly
relativistic material.Comment: Updated with the latest VLA and Chandra dat
A Decline in the X-ray through Radio Emission from GW170817 Continues to Support an Off-Axis Structured Jet
We present new observations of the binary neutron star merger GW170817 at
days post-merger, at radio (Karl G. Jansky Very Large
Array; VLA), X-ray (Chandra X-ray Observatory) and optical (Hubble Space
Telescope; HST) wavelengths. These observations provide the first evidence for
a turnover in the X-ray light curve, mirroring a decline in the radio emission
at significance. The radio-to-X-ray spectral energy
distribution exhibits no evolution into the declining phase. Our full
multi-wavelength dataset is consistent with the predicted behavior of our
previously published models of a successful structured jet expanding into a
low-density circumbinary medium, but pure cocoon models with a choked jet
cannot be ruled out. If future observations continue to track our predictions,
we expect that the radio and X-ray emission will remain detectable until days post-merger.Comment: Accepted to ApJL. Updated version includes new VLA observations
extending through 2018 June
Novel approach to observing system simulation experiments improves information gain of surface-atmosphere field measurements
The observing system design of multidisciplinary field
measurements involves a variety of considerations on logistics, safety, and
science objectives. Typically, this is done based on investigator intuition
and designs of prior field measurements. However, there is potential for
considerable increases in efficiency, safety, and scientific success by
integrating numerical simulations in the design process. Here, we present a
novel numerical simulationâenvironmental response function (NSâERF)
approach to observing system simulation experiments that aids
surfaceâatmosphere synthesis at the interface of mesoscale and microscale
meteorology. In a case study we demonstrate application of the NSâERF
approach to optimize the Chequamegon Heterogeneous Ecosystem Energy-balance
Study Enabled by a High-density Extensive Array of Detectors 2019
(CHEESEHEAD19).
During CHEESEHEAD19 pre-field simulation experiments, we considered the
placement of 20 eddy covariance flux towers, operations for 72âh of
low-altitude flux aircraft measurements, and integration of various remote
sensing data products. A 2âh high-resolution large eddy simulation
created a cloud-free virtual atmosphere for surface and meteorological
conditions characteristic of the field campaign domain and period. To
explore two specific design hypotheses we super-sampled this virtual
atmosphere as observed by 13 different yet simultaneous observing system
designs consisting of virtual ground, airborne, and satellite observations.
We then analyzed these virtual observations through ERFs to yield an optimal
aircraft flight strategy for augmenting a stratified random flux tower
network in combination with satellite retrievals.
We demonstrate how the novel NSâERF approach doubled CHEESEHEAD19's
potential to explore energy balance closure and spatial patterning science
objectives while substantially simplifying logistics. Owing to its modular
extensibility, NSâERF lends itself to optimizing observing system designs also
for natural climate solutions, emission inventory validation, urban air
quality, industry leak detection, and multi-species applications, among other
use cases.</p
Lung cancer induced in mice by the envelope protein of jaagsiekte sheep retrovirus (JSRV) closely resembles lung cancer in sheep infected with JSRV
BACKGROUND: Jaagsiekte sheep retrovirus (JSRV) causes a lethal lung cancer in sheep and goats. Expression of the JSRV envelope (Env) protein in mouse lung, by using a replication-defective adeno-associated virus type 6 (AAV6) vector, induces tumors resembling those seen in sheep. However, the mouse and sheep tumors have not been carefully compared to determine if Env expression alone in mice can account for the disease features observed in sheep, or whether additional aspects of virus replication in sheep are important, such as oncogene activation following retrovirus integration into the host cell genome. RESULTS: We have generated mouse monoclonal antibodies (Mab) against JSRV Env and have used these to study mouse and sheep lung tumor histology. These Mab detect Env expression in tumors in sheep infected with JSRV from around the world with high sensitivity and specificity. Mouse and sheep tumors consisted mainly of well-differentiated adenomatous foci with little histological evidence of anaplasia, but at long times after vector exposure some mouse tumors did have a more malignant appearance typical of adenocarcinoma. In addition to epithelial cell tumors, lungs of three of 29 sheep examined contained fibroblastic cell masses that expressed Env and appeared to be separate neoplasms. The Mab also stained nasal adenocarcinoma tissue from one United States sheep, which we show was due to expression of Env from ovine enzootic nasal tumor virus (ENTV), a virus closely related to JSRV. Systemic administration of the AAV6 vector encoding JSRV Env to mice produced numerous hepatocellular tumors, and some hemangiomas and hemangiosarcomas, showing that the Env protein can induce tumors in multiple cell types. CONCLUSION: Lung cancers induced by JSRV infection in sheep and by JSRV Env expression in mice have similar histologic features and are primarily characterized by adenomatous proliferation of peripheral lung epithelial cells. Thus it is unnecessary to invoke a role for insertional mutagenesis, gene activation, viral replication, or expression of other viral gene products in sheep lung tumorigenesis, although these processes may play a role in other clinically less important sequelae of JSRV infection such as metastasis observed with variable frequency in sheep
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