244 research outputs found
Multi-Phase Manganese Mineralization in the Noamundi Synclinorium, East Indian Shield
Manganese mineralization associated with phyllites in and around Joda, Odisha belongs to the Iron Ore Group of Noamundi basin and is a part of Jamda-Koira belt of East Indian Shield. The present study area comprises low to medium grade tectonites containing economic resources of both iron and manganese. Present study is concentrated on Manganese mineralization. Field study and petro-mineralogical observations reveal syngenetic character of manganese ores comprising lowT higher oxides viz. pyrolusite, cryptomelane, manganite as major Mn-minerals along with highT lower oxides viz. jacobsite, bixbyite, braunite and hausmannite as minor Mn-minerals. The Mn-ore bodies and associated phyllites have undergone multiple phases of deformation and metamorphism followed by hydrothermal and supergene processes. Four deformational phases have been deciphered during field study. Geochemical analyses of ores and phyllitic host rocks show high values of Al2O3, TiO2, Ba, Co, Ni, Cr, Cu, Sc, V, As, Zn but depletion of Sr, Yb, Sm, Nb. Geochemical data infer ores to be a recycling product originally derived from a mafic crustal source of tholeiitic character. Age data obtained from Sm-Nd ratio of two rock samples are 3.46 Ga and 2.79 Ga. Present work provides a critical assessment on the multiphase mineralization of manganese ores
Universal precaution: practice among doctors in a tertiary care hospital in Manipur
Background: Health workers especially doctors are always at higher risk of exposure to blood borne pathogens in day to day practice. Universal precaution is the only strategy so that all these infections could be prevented. The objective of the study was to assess the practice of Universal Precautions among doctors & factors influencing its use in a tertiary health centre of Manipur.Methods: Cross-sectional study was conducted among the doctors in a tertiary health care centre of Manipur during October 2011 to September 2013. Structured questionnaire was used to collect data. Descriptive statistics like percentage was used to describe the findings using SPSS 20.Results: Total respondents were 366 doctors. Response rate was 98%. Total of 125 (34.2%) respondents always used glove as a measure of universal precaution. Hand-washing after removal of gloves was practiced by more than half of the respondents. Around 2 in 10 participants never used personal protective equipments like gown & mask. Around 7 in 10 participants always practiced recapping after use. Total of 150 respondents (41%) used to dispose sharps in sharp and liquid proof container with removing syringe.74.3% mentioned the reasoning of not practicing universal precaution was lack of supply of personal protective equipment. A total of 50 respondents told that emergency situation was also responsible for not adhering to the practice. Work stress (1.6%), time constraint (5.7%), lack of display of guidelines (3.8%) were the reasons mentioned by few of them.Conclusions: Universal precaution practice was poor. Training of the health care workers, proper equipment supply, posters displaying guidelines and proper hospital policy of patient load management would help in improving the implementation of universal precaution thus restoring occupational safety of health care workers
Sound Radiated by a Supercritical Airfoil Operating in the Incompressible Regime
Measurements of far-field sound radiated by two and three-dimensional supercritical airfoils (ONERA OAT 15A) placed in a low Mach number flow were performed in an anechoic open-jet facility. The chord-based Reynolds numbers were between 156,000 and 468,000, while the Mach numbers ranged between 0.04 and 0.13. For the three-dimensional airfoil, two different aspect ratios (span-to-chord ratio) of 1.0 and 1.5 were considered. For comparison, the sound radiated by a symmetric NACA 0012 and cambered NACA 2412 airfoil was also measured under the same conditions. The noise from the two-dimensional airfoil was found to scale on the fifth power of Mach number. The noise generated by the cross-flow across the tip was the dominant noise source for the three-dimensional airfoils, particularly under high-lift conditions where it exceeds the noise from the mid-span portion across the considered frequency range. The tip noise spectra for the supercritical airfoils exhibit a prominent peak that scales with the free-stream velocity, but its frequency is a weak function of the lift on the airfoil and the aspect ratio. No such peak was observed for the NACA profiles even for higher lift conditions. The beamformed source maps for NACA profiles reveal an intense high-frequency noise source near the tip leading-edge which is much weaker for the supercritical airfoil due to differences in the curvature of the profiles. The tip noise spectra for the supercritical airfoil can be scaled on the fourth power of Mach number and the length-scale associated with the spectral peak. The tip noise peak magnitude and frequencies were found to be nearly independent of the airfoil aspect ratio; however, a reduction in AR was found to shift the tip noise source region further inboard. Stereo particle image velocimetry (PIV) measurements performed in a cross-plane behind the three-dimensional airfoils show that this is because a reduction in AR also shifts vortex core towards the mid-span. The PIV results were also used to quantify the meander of the tip vortex and it is shown that the amplitude of vortex meandering is independent of the angle of attack and the aspect ratio with a value between 0.5 – 0.6% of the chord-length for all cases considered
Time Evolution of a Supply Chain Network: Kinetic Modeling
Resilient supply chains are often inherently dependent on the nature of their complex interconnected networks that are simultaneously multi-dimensional and multi-layered. This article presents a Supply Chain Network (SCN) model that can be used to regulate downstream relationships towards a sustainable SME using a 4-component cost function structure - Environmental (E), Demand (D), Economic (E), and Social (S). As a major generalization to the existing practice of using phenomenological interrelationships between the EDES cost kernels, we propose a complementary time varying model of a cost function, based on Lagrangian mechanics (incorporating SCN constraints through Lagrange multipliers), to analyze the time evolution of the SCN variables to interpret the competition between economic inertia and market potential. Multicriteria decision making, based on an Analytic Hierarchy Process (AHP), ranks performance quality, identifying key business decision makers. The model is first solved numerically and then validated against real data pertaining to two Small and Medium Enterprises (SMEs) from diverse domains, establishing the domain-independent nature of the model. The results quantify how increases in a production line without appropriate consideration of market volatility can lead to bankruptcy, and how high transportation cost together with increased production may lead to a break-even state. The model also predicts the time it takes a policy change to reinvigorate sales, thereby forecasting best practice operational procedure that ensures holistic sustainability on all four sustainability fronts
Strategic maintenance technique selection using combined quality function deployment, the analytic hierarchy process and the benefit of doubt approach
The business performance of manufacturing organizations depends on the reliability and productivity of equipment, machineries and entire manufacturing system. Therefore, the main role of maintenance and production managers is to keep manufacturing system always up by adopting most appropriate maintenance methods. There are alternative maintenance techniques for each machine, the selection of which depend on multiple factors. The contemporary approaches to maintenance technique selection emphasize on operational needs and economic factors only. As the reliability of production systems is the strategic intent of manufacturing organizations, maintenance technique selection must consider strategic factors of the concerned organization along with operational and economic criteria. The main aim of this research is to develop a method for selecting the most appropriate maintenance technique for manufacturing industry with the consideration of strategic, planning and operational criteria through involvement of relevant stakeholders. The proposed method combines quality function deployment (QFD), the analytic hierarchy process (AHP) and the benefit of doubt (BoD) approach. QFD links strategic intents of the organizations with the planning and operational needs, the AHP helps in prioritizing the criteria for selection and ranking the alternative maintenance techniques, and the BoD approach facilitates analysing robustness of the method through sensitivity analysis through setting the realistic limits for decision making. The proposed method has been applied to maintenance technique selection problems of three productive systems of a gear manufacturing organization in India to demonstrate its effectiveness
Into Thick(er) Air? Oxygen Availability at Humans’ Physiological Frontier on Mount Everest
Global audiences are captivated by climbers pushing themselves to the limits in the hypoxic environment of Mount Everest. However, air pressure sets oxygen abundance, meaning it varies with the weather and climate warming. This presents safety issues for mountaineers, but also an opportunity for public engagement around climate change. Here we blend new observations from Everest with ERA5 reanalysis (1979- 2019) and climate model results to address both perspectives. We find that plausible warming could generate subtle but physiologically relevant changes in summit oxygen availability, including an almost 5% increase in annual minimum VO 2 max for 2°C warming since pre-industrial. In the current climate we find evidence of swings in pressure sufficient to change Everest’s apparent elevation by almost 750 m. Winter pressures can also plunge lower than previously reported, highlighting the importance of air pressure forecasts for the safety of those trying to push the physiological frontier on Mt. Everest
Emergent risks in the Mt. Everest region in the time of anthropogenic climate change
In April and May 2019, as a part of the National Geographic and Roxel
Perpetual Planet Everest Expedition, the most interdisciplinary scientific ever
was launched. This research identified changing dynamics, including emergent
risks resulting from natural and anthropogenic change to the natural system. We
have identified compounded risks to ecosystem and human health, geologic
hazards, and changing climate conditions that impact the local community,
climbers, and trekkeers in the future. This review brings together perspectives
from across the biological, geological, and health sciences to better
understand emergent risks on Mt. Everest and in the Khumbu region.
Understanding and mitigating these risks is critical for the ~10,000 people
living in the Khumbu region, as well as the thousands of visiting trekkers and
the hundreds of climbers who attempt to summit each year.Comment: 21 pages, 2 figure
Nucleophile-Catalyzed Additions to Activated Triple Bonds. Protection of Lactams, Imides, and Nucleosides with MocVinyl and Related Groups
Additions of lactams, imides, (S)-4-benzyl-1,3-oxazolidin-2-one, 2-pyridone, pyrimidine-2,4-diones (AZT derivatives), or inosines to the electron-deficient triple bonds of methyl propynoate, tert-butyl propynoate, 3-butyn-2-one, N-propynoylmorpholine, or N-methoxy-N-methylpropynamide in the presence of many potential catalysts were examined. DABCO and, second, DMAP appeared to be the best (highest reaction rates and E/Z ratios), while RuCl3, RuClCp*(PPh3)2, AuCl, AuCl(PPh3), CuI, and Cu2(OTf)2 were incapable of catalyzing such additions. The groups incorporated (for example, the 2-(methoxycarbonyl)ethenyl group that we name MocVinyl) serve as protecting groups for the above-mentioned heterocyclic CONH or CONHCO moieties. Deprotections were accomplished via exchange with good nucleophiles: the 1-dodecanethiolate anion turned out to be the most general and efficient reagent, but in some particular cases other nucleophiles also worked (e.g., MocVinyl-inosines can be cleaved with succinimide anion). Some structural and mechanistic details have been accounted for with the help of DFT and MP2 calculations
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