1,124 research outputs found

    Operational loopwheel suspension systems for Mars Rover demonstration model: Loopwheel failure report

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    The results are presented from the analysis of a failure which occurred in the fiberglass loop of one of the Loopwheel traction elements delivered to the Jet Propulsion Laboratory (JPL) for use on the JPL Mars Rover demonstration model. The loop failed in compression in the outer fibers forming a hinge which, through cycling, caused the inner fibers to break. The probable cause of this failure was the load being introduced as point loads at the center of the loop causing high compressive stresses and early buckling. To decrease the stress level and delay buckling, the tread lugs can be reshaped so that the entire lug contacts the ground when the loop is loaded. This can be accomplished through removal of lug material, starting with zero removal at the outer edge and linearly increasing to one-half of the lug thickness at the center

    The Effect of Inlet Pressure and Temperature on the Efficiency of a Single-stage Impulse Turbine Having an 11.0-inch Pitch-line Diameter Wheel

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    Efficiency tests have been conducted on a single-stage impulse engine having an 11-inch pitch-line diameter wheel with inserted buckets and a fabricated nozzle diaphragm. The tests were made to determine the effect of inlet pressure, Inlet temperature, speed, and pressure ratio on the turbine efficiency. An analysis is presented that relates the effect of inlet pressure and temperature to the Reynolds number of the flow. The agreement between the analysis and the experimental data indicates that the changes in turbine efficiency with Inlet pressure and temperature may be principally a Reynolds number effect

    Morphology of the First Zoeal Stage of Platypodiella spectabilis (Herbst, 1794) (Decapoda, Brachyura, Xanthidae) Obtained in the Laboratory

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    Ovigerous females of the xanthid crab Platypodiella spectabilis (Herbst, 1794) were obtained from 2 widely separated localities: the Ubatuba coast (Félix Beach, São Paulo) of Brazil and Guana Island in the British Virgin Islands (BVI). First stage zoea larvae were obtained from females at both locations. Those from Brazil are described and illustrated. The first zoea bears dorsal, rostral, and lateral carapace spines, plus a well-developed and spinose antennal protopod that bears a greatly reduced exopod with 2 minute setae. This antennal morphology, along with other characters, places the species among the “Group I” xanthid zoeas of Rice (1980) and Martin (1984, 1988). Differences between larvae from Brazil and those from the BVI are minor and are attributed to within-species variation. Characters that serve to separate these larvae from those of cooccuring xanthids are presented. Comments on the distribution and size of Platypodiella spectabilis are included

    Методичні рекомендації щодо проходження науково-практичної підготовки магістрів спеціальності 8.05030101 Розробка родовищ та видобування корисних копалин

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    Подано методичні матеріали щодо проходження науково-практичної підготовки з освітньо-кваліфікаційної програми магістрів спеціальності 8.05030101 Розробка родовищ та видобування корисних копалин

    Interference with Oligomerization and Glycosaminoglycan Binding of the Chemokine CCL5 Improves Experimental Liver Injury

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    Background: The chemokine CCL5 is involved in the recruitment of immune cells and a subsequent activation of hepatic stellate cells (HSC) after liver injury. We here investigate whether inhibition of CCL5 oligomerization and glycosaminoglycan binding by a mutated CCL5 protein ( 44 AANA 47-CCL5) has the potential to ameliorate liver cell injury and fibrosis in vivo. Methodology: Liver injury was induced in C57BL/6 mice by intraperitoneal injection of carbon tetrachloride (CCl4) inan acute and a chronic liver injury model. Simultaneously, mice received either 44 AANA 47-CCL5 or vehicle. Liver cell necrosis and fibrosis was analyzed by histology, and measurement of serum transaminases and hydroxyproline. Intrahepatic mRNA expression of fibrosis and inflammation related genes were determined by quantitative RT-PCR and infiltration of immune cells was assessed by FACS analysis and immunocytochemistry. In vitro, HSC were stimulated with conditioned media of T-cell enriched splenocytes. Principal Findings: 44 AANA 47-CCL5 treated mice displayed a significantly reduced degree of acute liver injury (liver cell necrosis, transaminases) and fibrosis (Sirus red positive area and hydroxyproline content) compared to vehicle treated mice. Ameliorated fibrosis by 44 AANA 47-CCL5 was associated with a decreased expression of fibrosis related genes, decreased a-smoth muscle antigen (aSMA) and a reduction of infiltrating immune cells. In the acute model, 44 AANA 47-CCL5 treated mice displayed a reduced immune cell infiltration and mRNA levels of TNF, IL-1 and CCL3 compared to vehicle treated mice. I

    DFT Calculations as a Tool to Analyse Quadrupole Splittings of Spin Crossover Fe(II) complexes

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    Density functional methods have been applied to calculate the quadrupole splitting of a series of iron(II) spin crossover complexes. Experimental and calculated values are in reasonable agreement. In one case spin-orbit coupling is necessary to explain the very small quadrupole splitting value of 0.77 mm/s at 293 K for a high-spin isomer
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