2,383 research outputs found
Managing mine road maintenance interventions using mine truck on-board data
The management of unpaved mine road networks on large surface mines rarely results in optimal road maintenance strategies and minimised total road-user costs. This is ascribed mostly to the complex and dynamic combination of variable road networks and loading and discharge points. In a dynamic mining environment - typically those mines in which production is managed by a centralised truck dispatch system - there is no guarantee that a particular road maintenance intervention will contribute significantly to reducing total road-user costs or increasing productivity. Most large surface mines operating ultra-heavy mine trucks rely on an integrated on-board diagnostic data collation, communication and GPS-asset location system as a real-time fleet management tool. By extending this system to incorporate a multi-sensor analytical procedure in which specific truck vital signs are monitored and filtered, a road defect can be recognised and a trigger level set to relay the location of defects on the mine haul road to the centralised truck data management system. Previous work established the feasibility of the multi-sensor approach to road defect recognition on large mine haul trucks, and outlined the defect recognition, analytical and modelling issues and system limitations. This paper presents the development of the analytical procedure used as a basis for evaluating the truck on-board data to establish maintenance priorities amongst a network of mine roads. Following an introduction to the system architecture, the results of system field trials are analysed and the results discussed in the light of defect density and traffic volume as the primary variables in an approach to prioritising road maintenance. The paper concludes that by supplementing the existing mine communication and asset management systems, road maintenance can be managed on a near real-time basis and maintenance equipment dispatched to where most immediate benefit will realised from a maintenance intervention on the network, thereby generating the maximum improvement in service and reduction in cost per ton hauled
Young stars and dust in AFGL437: NICMOS/HST polarimetric imaging of an outflow source
We present near infrared broad band and polarimetric images of the compact
star forming cluster AFGL437 obtained with the NICMOS instrument aboard HST.
Our high resolution images reveal a well collimated bipolar reflection
nebulosity in the cluster and allow us to identify WK34 as the illuminating
source. The scattered light in the bipolar nebulosity centered on this source
is very highly polarized (up to 79%). Such high levels of polarization implies
a distribution of dust grains lacking large grains, contrary to the usual dust
models of dark clouds. We discuss the geometry of the dust distribution giving
rise to the bipolar reflection nebulosity and make mass estimates for the
underlying scattering material. We find that the most likely inclination of the
bipolar nebulosity, south lobe inclined towards Earth, is consistent with the
inclination of the large scale CO molecular outflow associated with the
cluster, strengthening the identification of WK34 as the source powering it.Comment: 26 pages, 10 figues. Accepted for publication in the Astrophysical
Journa
Caveolin-1 expression is elevated in claudin-low mammary tumor cells
<p>Abstract</p> <p>Background</p> <p>Caveolin-1 is a scaffolding protein found in plasma membrane invaginations known as caveolae. Caveolin-1 can regulate a number of intracellular processes such as signal transduction, cholesterol metabolism and vesicular transport. With respect to breast cancer caveolin-1 has been observed in both tumor cells and stromal cells surrounding tumors however most of the recent research has focused on how the loss of caveolin-1 in the stromal cells surrounding the tumor alters the tumor microenvironment.</p> <p>Methods</p> <p>Caveolin-1 expression was evaluated in (1) mammary tumors induced by the transgenic overexpression of the type I insulin-like growth factor receptor (IGF-IR), (2) mammary tumors that became independent of IGF-IR signalling and acquired a claudin-low genotype, (3) two murine mammary epithelial tumor cell lines and (4) two murine mammary claudin-low tumor cell lines.</p> <p>Results</p> <p>We found that mammary tumors induced by IGF-IR overexpression expressed low levels of caveolin-1 while mammary tumors that became independent of IGF-IR signalling expressed considerably higher levels of caveolin-1. Interestingly, pockets of caveolin-1 positive cells could be observed in some of the IGF-IR-induced mammary tumors and these caveolin-1 positive cells were associated with tumor cells that expressed basal cytokeratins (cytokeratins 5 and 14). This caveolin-1 expression pattern was maintained in the murine mammary tumor cell lines in that the epithelial mammary tumor cell lines expressed little or no caveolin-1 while the claudin-low cell lines expressed caveolin-1.</p> <p>Conclusions</p> <p>Our model indicates that mammary tumor cells with epithelial characteristics lack caveolin-1 while mesenchymal tumor cells express caveolin-1 suggesting that caveolin-1 may serve as a marker of mammary tumor cells with mesenchymal characteristics such as claudin-low breast tumors.</p
The hydrochloride salt of l-ecgonine, a congener of cocaine
The title compound, (1R,2R,3S,5S,8S)-3-hydroxy-8-methyl-8-azoniabicyclo[3.2.1]octane-2-carboxylic acid chloride, C9H16NO3
+·Cl−, is both a metabolite and a precursor of the tropane alkaloid l-cocaine. The carboxyl group is not involved in dimerization, but instead donates a hydrogen bond to the chloride counter-ion, which participates in two additional hydrogen bonds. The chloride ion is thus trigonally hydrogen bonded to three l-ecgonine cations. The quarternary N proton is intramolecularly hydrogen bonded to the carboxyl C=O group, an arrangement identical to that reported for both (−)-norcocaine and the tetrachloroaurate(III) salt of l-cocaine. One close intermolecular C—H⋯O contact exists
4-(2-Benzoylethyl)benzoic acid
The title compound, C16H14O3, adopts a conformation in which each functional group is almost coplanar with its adjacent ring, while the two aromatic rings are twisted with respect to one another with a dihedral angle of 78.51 (3)°. The compound dimerizes by standard centrosymmetric hydrogen-bonded carboxyl pairing [O⋯O = 2.6218 (11) Å and O—H⋯O = 176 (2)°]. The packing includes two intermolecular C—H⋯O close contacts with the ketone group
(-)-Isosantonic acid: Alteration of the hydrogen-bonding mode by configurational inversion at a single centre in a γ,ε- diketocarboxylic acid
The title diketo acid, (1R,3aS,6aS,7R,9S)-(-)-α,3a,7-trimethyl-5,8- dioxo-1,4-ethanoperhydropentalene-1-acetic acid (C15H 20O4), is shown to aggregate in the crystal structure as acid-to-ketone hydrogen-bonding catemers, whose chains follow 21 screw axes from each carboxyl to a ketone in a neighbouring molecule [O⋯O = 2.7472(13) and O⋯H - O = 172.7(17)°]. Two parallel counterdirectional screw-related single-strand hydrogen-bonding chains pass through the cell in the a direction. Six intermolecular C - H⋯O=C close contacts are found. Comparisons are drawn with a diastereomer having the opposite configuration at the methylated chiral centre adjacent to the carboxyl group.Fil: Zinczuk, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Ruveda, Edmundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Lalancette, Roger A.. Rutgers University; Estados UnidosFil: Thompson, Hugh W.. Rutgers University; Estados Unido
(±)-trans-3-Oxo-1,2,3,4,4a,9,10,10a-octahydrophenanthrene-10a-carboxylic acid: catemeric hydrogen bonding in a δ-keto acid
The title compound, C15H16O3, aggregates as hydrogen-bonded catemers progressing from each carboxyl to the ketone of a screw-related neighbor [O⋯O = 2.6675 (14) Å and O—H⋯O = 170°]. Two parallel centrosymmetrically related single-strand hydrogen-bonding helices proceed through the cell in the b-axis direction. The packing includes three intermolecular C—H⋯O=C close contacts, involving both the ketone and the carboxyl group. The structure is isomorphous with that of the previously described Δ4 α,β-unsaturated ketone
(2RS,8aRS)-6-Oxo-1,2,3,4,6,7,8,8a-octahydronaphthalene-2-carboxylic acid
The title racemate, C11H14O3, aggregates in the crystal structure as acid-to-ketone O—H⋯O hydrogen-bonding catemers whose components are glide-related. The relative stereochemistry at the carboxyl group arises spontaneously during the synthesis. Two intermolecular C—H⋯O=C close contacts were found, both involving the acid group
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