4,419 research outputs found
Comparative potential of black tea leaves waste to granular activated carbon in adsorption of endocrine disrupting compounds from aqueous solution
The adsorption properties and mechanics of selected endocrine disrupting compounds; 17 β-estradiol, 17 α – ethinylestradiol and bisphenol A on locally available black tea leaves waste and granular activated carbon were investigated. The results obtained indicated that the kinetics of adsorption were pH, adsorbent dose, contact time and temperature dependent with equilibrium being reached at 20 to 40 minutes for tea leaves waste and 40 to 60 minutes for granular activated compound. Maximum adsorption capacities of 3.46, 2.44 and 18.35 mg/g were achieved for tea leaves waste compared to granular activated compound capacities of 4.01, 2.97 and 16.26 mg/g for 17 β- estradiol, 17 α-ethinylestradiol and bisphenol A respectively. Tea leaves waste adsorption followed pseudo-first order kinetics while granular activated compound fitted better to the pseudo-second order kinetic model. The experimental isotherm data for both tea leaves waste and granular activated compound showed a good fit to the Langmuir, Freundlich and Temkin isotherm models with the Langmuir model showing the best fit. The thermodynamic and kinetic data for the adsorption indicated that the adsorption process for tea leaves waste was predominantly by physical adsorption while the granular activated compound adsorption was more chemical in nature. The results have demonstrated the potential of waste tea leaves for the adsorptive removal of endocrine disrupting compounds from water
Empirical evidence on the relationships between concentration and profitability in Latin American banking
There has been growth in globalization as a result of increased liberalization. This has also resulted in an increase in the role of financial institutions, such as banks. It is the purpose of this study to test Classen’s (2001) hypothesis that increase foreign bank presence has positive welfare implications and that the functioning of national banking markets are improved as a result. Using financial data for 2003 this paper will examine the influence of foreign bank entry on Latin American domestic markets.Latin American banking; Concentration and Profitability; Foreign Bank Influence
Hepatoprotective effect of an aqueous extract of the leaves of Acalypha wilkesiana 'Godseffiana' Muell Arg (Euphorbiaceae) against carbon tetrachloride induced liver injury in rats
The potential of aqueous extract of the leaves of Acalypha wilkesiana, to protect against carbon tetrachloride induced liver damage was investigated in Wistar albino rats. The carbon tetrachloride was prepared 1:5 (v:v) in olive oil, and administered subcutaneously at 1 mL/kg body weight. The extract was administered to both normal and carbon tetrachloride treated rats at 100, 200 and 300 mg/kg. On fractionation and gas chromatographic analysis of the crude aqueous extract, thirty nine known alkaloids were detected, consisting mainly of akuamidine (69.027 %), voacangine (26.226 %), echitamine (1.974 %), echitamidine
(0.599 %), lupanine (0.521 %) and augustamine (0.278 %). Compared to test control, the treatment dose dependently produced significantly lower (P<0.05) alkaline phosphatase, aspartate and alanine transaminase activities. Histopathological studies on the liver sections showed that pre-treatment with the extract protected against carbon tetrachloride induced fatty
degeneration of hepatocytes, thus, confirming the results of the biochemical studies. The above results imply that treatment with the plant extract protects the liver against carbon tetrachloride
induced hepatotoxicity, therefore, justifying the use of Acalypha wilkesiana in African traditional health care for the management of liver problems
Life Support and Habitation Systems: Crew Support and Protection for Human Exploration Missions Beyond Low Earth Orbit
Life Support and Habitation Systems (LSHS) is one of 10 Foundational Domains as part of the National Aeronautics and Space Administration s proposed Enabling Technology Development and Demonstration (ETDD) Program. LSHS will develop and mature technologies to sustain life on long duration human missions beyond Low Earth Orbit that are reliable, have minimal logistics supply and increase self-sufficiency. For long duration exploration missions, further closure of life support systems is paramount, including focus on key technologies for atmosphere revitalization, water recovery, waste management, thermal control and crew accommodation that recover additional consumable mass, reduce requirements for power, volume, heat rejection, crew involvement, and which have increased reliability and capability. Other areas of focus include technologies for radiation protection, environmental monitoring and fire protection. Beyond LEO, return to Earth will be constrained. The potability of recycled water and purity of regenerated air must be measured and certified aboard the spacecraft. Missions must be able to recover from fire events through early detection, use of non-toxic suppression agents, and operation of recovery systems that protect on-board Environmental Control and Life Support (ECLS) hardware. Without the protection of the Earth s geomagnetic field, missions beyond LEO must have improved radiation shielding and dosimetry, as well as warning systems to protect the crew against solar particle events. This paper will describe plans for the new LSHS Foundational Domain and mission factors that will shape its technology development portfolio
Methods for Estimating Environmental Effects and Constraints on NexGen: High Density Case Study
This document provides a summary of the current methods developed by Metron Aviation for the estimate of environmental effects and constraints on the Next Generation Air Transportation System (NextGen). This body of work incorporates many of the key elements necessary to achieve such an estimate. Each section contains the background and motivation for the technical elements of the work, a description of the methods used, and possible next steps. The current methods described in this document were selected in an attempt to provide a good balance between accuracy and fairly rapid turn around times to best advance Joint Planning and Development Office (JPDO) System Modeling and Analysis Division (SMAD) objectives while also supporting the needs of the JPDO Environmental Working Group (EWG). In particular this document describes methods applied to support the High Density (HD) Case Study performed during the spring of 2008. A reference day (in 2006) is modeled to describe current system capabilities while the future demand is applied to multiple alternatives to analyze system performance. The major variables in the alternatives are operational/procedural capabilities for airport, terminal, and en route airspace along with projected improvements to airframe, engine and navigational equipment
Cochlear Damage Affects Neurotransmitter Chemistry in the Central Auditory System
Tinnitus, the perception of a monotonous sound not actually present in the environment, affects nearly 20% of the population of the United States. Although there has been great progress in tinnitus research over the past 25 years, the neurochemical basis of tinnitus is still poorly understood. We review current research about the effects of various types of cochlear damage on the neurotransmitter chemistry in the central auditory system and document evidence that different changes in this chemistry can underlie similar behaviorally measured tinnitus symptoms. Most available data have been obtained from rodents following cochlear damage produced by cochlear ablation, loud sound, or ototoxic drugs. Effects on neurotransmitter systems have been measured as changes in neurotransmitter level, synthesis, release, uptake, and receptors. In this review, magnitudes of changes are presented for neurotransmitter-related amino acids, acetylcholine, and serotonin. A variety of effects have been found in these studies that may be related to animal model, survival time, type of cochlear damage, or methodology. The overall impression from the evidence presented is that any imbalance of neurotransmitter-related chemistry could disrupt auditory processing in such a way as to produce tinnitus
Effects of a Self-Selected Pace on VO2max during a Running Test to Volitional Exhaustion
Please view abstract in the attached PDF file
Archaeological Test Excavations at 41MV57: The Seco Mines Project, Maverick County, Texas
In mid-February, 1977, an archaeological field team from the Center for Archaeological Research, The University of Texas at San Antonio, conducted investigations at prehistoric site 41 MV 57 in Maverick County, Texas. The site is located along a tributary of Seco Creek and is to be modified by the installation of a sewage collection system (the Seco Mines Project)
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