Studies on mechanical behavior of glass epoxy composites with induced defects and correlations with NDT characterization parameters

Degradation in mechanical properties (compression, flexural and ILS) of glass epoxy composite laminates with induced defects (simulating delaminations) was studied. The defects were characterized by using the A-scan ultrasonic pulse-echo technique. The two A-scan parameters, viz. the back wall echo amplitude and time of flight, were followed respectively, as functions of the defect size (diameter) and its location in the laminate thickness. The mechanical properties of laminates were evaluated destructively for different defect sizes and locations. An attempt has been made to express the mechanical properties in terms of the two NDT scan parameters characterizing the defects and empirical equations presente

Development of a flexible image-based approach for studying signal transduction in isolated arterioles

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on May 11, 2009)Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2007.Dissertations, Academic -- University of Missouri--Columbia -- Biological engineering.Myogenic constriction in arterioles occurs when membrane tension leads to smooth muscle depolarization and voltage-gated calcium channel activation. A barrier to understanding the exact signaling events is the limited ability of glass electrodes to follow temporal changes in membrane potential (Em). This study aimed to develop an imaging station to measure Em, [Ca²+]i and diameter in isolated arterioles. A Forster Resonance Enery Transfer (FRET) approach was proposed for Em meaurement due to enhanced sensitivity and temporal responsiveness. FRET indicators used were CC2-DMPE (Coumarin-labelled Phospholipid, Donor, ex: 405nm) and DisBAC₄(3) (Oxonol, acceptor). For measurement of [Ca²+]i Fluo-4 AM (ex 488nm) was used. Initial studies examined toxicity of the multiple fluorophores. Isolated cells remained viable after loading with the fluorophores. Arterioles maintained myogenic, and agonist, responsiveness pre and post dye loading suggesting a lack of toxicity. Spectral characteristics of the fluorophores used in the project required specific optical filter units and development of a. custom built optical system. Using the system, FRET was demonstrated, as was the ability to detect changes in fluorescence signal to known depolarizing stimuli. The developed system is now ready for translation to the study of myogenic signaling in intact and functional arterioles

Analysis of Irregular High Raised RCC Buildings by Using Tuned Mass Damping System

Tall buildings are indispensable in urban areas due to high cost of land, shortage of open spaces and scarcity of lands. The tall buildings are in general highly vulnerable to lateral forces arising out of cyclones and earthquakes. Designing the structures to withstand these occasional lateral forces is very expensive; hence it is not always desirable. The measures to reduce the lateral forces are by way of reducing the weight of the structure and by reducing the exposed faces to thwart wind. However the architectural requirement and the utility of the building have to be honored at all times by the structural designer. Though the technique of Tuned mass damping (TMD) is very well appreciated, the mathematical implications involved in finding the magnitude of mass, stiffness and damping of the TMD is highly intricate and suitable TMD system for a given building structure, which shall remain an integral part of the structure itself, placed on top of the building yet serves the purpose of reducing the earthquake effects on buildings. The TMD methodology adopted for three irregular R.C. framed models having + (Plus)-shape , C-shape and T-shape in plan. This apart the device shall find its utility for all zones of seismic activity and ground/structural conditions and introduces various structural motion control methodologies with focus on tuned mass damping systems. The control properties and some aspects of TMD parameters are outlined. ETABS software is used for dynamic analysis of various shapes of the framed buildings

Global Tobacco Control and Economic Norms: An Analysis of Normative Commitments in Kenya, Malawi And Zambia

Tobacco control norms have gained momentum over the past decade. To date 43 of 47 Sub-Saharan African countries are party to the Framework Convention on Tobacco Control (FCTC). The near universal adoption of the FCTC illustrates the increasing strength of these norms, although the level of commitment to implement the provisions varies widely. However, tobacco control is enmeshed in a web of international norms that has bearing on how governments implement and strengthen tobacco control measures. Given that economic arguments in favor of tobacco production remain a prominent barrier to tobacco control efforts, there is a continued need to examine how economic sectors frame and mobilize their policy commitments to tobacco production. This study explores the proposition that divergence of international norms fosters policy divergence within governments. This study was conducted in three African countries: Kenya, Malawi, and Zambia. These countries represent a continuum of tobacco control policy, whereby Kenya is one of the most advanced countries in Africa in this respect, whereas Malawi is one of the few countries that is not a party to the FCTC and has implemented few measures. We conducted 55 key informant interviews (Zambia = 23; Kenya = 17; Malawi = 15). Data analysis involved deductive coding of interview transcripts and notes to identify reference to international norms (i.e. commitments, agreements, institutions), coupled with an inductive analysis that sought to interpret the meaning participants ascribe to these norms. Our analysis suggests that commitments to tobacco control have yet to penetrate non-health sectors, who perceive tobacco control as largely in conflict with international economic norms. The reasons for this perceived conflict seems to include: (1) an entrenched and narrow conceptualization of economic development norms, (2) the power of economic interests to shape policy discourses, and (3) a structural divide between sectors in the form of bureaucratic silos

Enhancement of lipid production in two marine microalgae under different levels of nitrogen and phosphorus deficiency

Microalgae are important food sources for aquaculture animals. Among the different factors which influence the biochemical composition of microalgae, nitrogen and phosphorus are two of the most important nutrient sources for growth and development. The present study aimed to assess the effects of nitrogen and phosphorus deficiency on lipid production of Chlorella sp. and Chaetoceros calcitrans. Early stationary phase culture of these species were exposed to different stress levels of nitrogen and phosphorus (25%, 50% and 75% of the full NO3-N and PO4-P concentration in the Conway media), and solvent extraction and gas-liquid chromatography methods were performed for analysis of lipid and fatty acid composition. The results revealed that lipid production in these two species significantly increased (P<0.05) as nitrogen and phosphorus decreased. The fatty acid proportion remained unaffected under nitrogen deficiency, while phosphorus limitation resulted in a decrease of saturated fatty acids and promoted a higher content of omega-3 fatty acids in these species. The protein and carbohydrate levels were also altered under limited nutrients. Therefore, these conditions could be used for enhanced lipid production in microalgae for aquaculture and other industrial applications

Dynamics of parasite population and its histopathological and histophysiological effects in the stomach of a freshwater fish

The caryophyllaeid cestode Lytocestoides fossilis infects the freshwater catfish Heteropneustes fossilis. The study was conducted for two consecutive years (2004-06) to record the bio-statistical data of the parasite. The incidence, intensity, density and index of infection of the parasite have been recorded. The infection was more during June to September, moderate during February to May and low during October to January. The parasite brought about severe histopathological changes in the stomach of infected fish. The changes observed in the stomach of fish included structural damage of the villi, inflammation, and fibrosis associated with hyperplasia and metaplasia. The hypertrophy of mucous layer led to vacuolation and necrosis. Histochemical changes were noticed with enhanced carbohydrate, protein and lipid contents. The enhanced substrate content in the infected organ might be due to the disfunctioning of the digestive tract, which results in the accumulation of various metabolites. Mucus secretion was triggered as a protective interaction against parasitic invasion. The parasitic infection affects the general metabolic state of the host and as the result, the fish becomes sluggish and moribund