Characterizations of Lead Free BNT-BT-KNN Ceramics Synthesized by Microwave Technique

Ferroelectrics have experienced a great deal of interest for more than half a century. Initially, ferroelectric ceramics were used as capacitor materials due to their high dielectric constants. With the preface of lead-zirconate-titanate (PZT), applications spread to transducers, actuators and many others. But because of the toxic nature of lead and serious environmental concerns there is an urgent need to develop lead free ferroelectrics to replace the currently leading lead based PZT. However, recognized lead-free ferroelectrics are not yet good enough to replace lead based materials. A considerable research attempt into lead-free alternatives to PZT began a few years ago. The purpose of this project was to develop leadfree ferroelectrics, which may ultimately replace PZT. The concept of combining three ferroelectric materials, which is before now morphotropic phase boundary compositions, in order to additional increase the ferroelectric properties was studied in detail. The three base compositions chosen were (0.89BNT-0.06BT-0.05KNN) and (0.92BNT-0.06BT-0.02KNN). BNT-BT-KNN was prepared by the solid state route. Calcination of the samples was done by using microwave at 900oC for both 10 and 20 minutes. In both the cases the phase was formed and the 10 minutes calcined samples were chosen for further synthesis to reduce the processing time. XRD of the compositions was done in which a single perovskite phase was formed. The samples were sintered using the microwave sintering method at 1150oC for 30 minutes. FESEM images of the samples were taken which show dense microstructure with uniform grain size and less apparent porosity. The study of dielectric properties and PE loop measurements were done to prove the ferroelectric nature of the sample

Modeling the impacts of pulsed riverine inflows on hydrodynamics and water quality in the Barataria Bay estuary

Eutrophication and coastal wetland loss are the major environmental problems affecting estuaries around the world. In Louisiana, controlled diversions of the Mississippi River water back into coastal wetlands are thought to be an important engineering solution that could reverse coastal land loss. There are concerns, however, that freshwater diversions may increase nutrient inputs and create severe eutrophication problems in estuaries and wetlands adjacent to the diversion sites. My dissertation research concerns modeling the effects of the observed and hypothetical freshwater diversion discharges on the hydrodynamics, salinity and water quality in the Barataria estuary, a deltaic estuary in south Louisiana. This estuary receives freshwater and nutrient discharges from the Davis Pond diversion, the world’s largest freshwater diversion project. I have implemented two Barataria Bay simulation models of differing complexity, a simple 6-box mass-balance model and a high resolution two-dimensional (2-D) coupled hydrology-hydrodynamic- water quality model. Model results have shown that the Barataria estuary imports nitrogen and exports carbon to the coastal ocean. Compared to the lower Mississippi River, the Barataria estuary appears to be a very small source of total organic carbon for the northern Gulf of Mexico and is unlikely to have a significant influence on the development of the Gulf’s hypoxia. Model simulations pointed out that the effects of different diversion discharges on salinity are most apparent in the middle and lower sections of the Barataria estuary. Further, tracer simulation experiments have shown that residence times differ markedly at different locations within the same water body due to differences in small scale hydrodynamics. Model simulations clearly demonstrated the importance of residence times for the overall functioning of the estuary. Model simulations also pointed out the differences in spatial patterns in phytoplankton response to distributed freshwater and nutrient inflows, reflecting the near-field control of nutrients and far-field control of residence times on phytoplankton standing stock. The models reiterate the fact that there are significant tradeoffs in using freshwater diversions in coastal restoration efforts, namely tradeoffs between hydrologic restoration and water quality effects

Regional water quality models for the prediction of eutrophication endpoints

Eutrophication is a process by which a waterbody progresses from its origin to its extinction. During this period, there is a gradual accumulation of nutrients and organic biomass, accompanied by a decrease in average depth of the water due to sediment accumulation, and an increase in primary productivity, usually in the form of dense algal blooms. Cultural eutrophication occurs when humans, through their various activities, greatly accelerate this process. Eutrophication can cause loss in species diversity, fish kills, and decrease the aesthetic value of a waterbody. The EPA is trying to prevent cultural eutrophication by setting standards for water quality criteria for each of the fourteen ecoregions in the United States. Nutrients are the most common pollutants affecting waterbodies. The EPA considers total phosphorous and total nitrogen as the two causal variables and chlorophyll a and Secchi depth as the two early indicator response variables. There are models that predict the relationship of chlorophyll a to phosphorous and chlorophyll a to nitrogen, but there are very few that combine phosphorous and nitrogen to predict chlorophyll a at a cross-sectional level. This study is concerned with fitting a linear model for the prediction of chlorophyll a, using phosphorous and nitrogen, for the fourteen ecoregions. Six combinations of the three variables have been tested (because of the different methods used to obtain each variable) to find out which model is the best with respect to model fit, number of observations, and geographical coverage. The best model can then be used in further studies to determine eutrophication end points at smaller and more homogeneous divisions of the ecoregion for better management of water quality in lakes

Economic and Fiscal Impacts of Refugees in Central Iowa: Opportunities for University Extension

An increasing refugee population has led to scrutiny of the effects of refugees in the United States. One way to assess effects is through studying economic and fiscal impacts. We used an input–output framework and refugee employment and wage data to estimate the short-term economic and fiscal impacts, both indirect and induced effects, of refugees living in central Iowa. Findings suggest that the employment and income multiplier effects are significant, although short-term fiscal impacts are negative. The study provides an objective assessment of an important and understudied group in central Iowa and could have relevance nationwide, including for Extension practitioners in developing or strengthening programming or contributing to policy formulation

Analysis of the Transient Response of a Capacitor-Excited Induction Generator for Unity Power Factor Load Condition using MATLAB/SIMULINK

Advantageous features of an induction generators are widely used in a single system like wind or micro turbo etc. It is operated in a capacitor excited or self excited mode to generate electrical energy in remote areas. The Main drawbacks of a CEIG under variable load conditions are poor voltage and frequency regulation .The aim of this paper is to provide a better understanding of the dynamic response of a capacitor-excited, squirrel cage induction generator that is carried out for determining the change in performance under the running condition from no-load to full-load. Voltage control, frequency control and temperature rise due to continuous running of the machine are evaluated using transient analysis. This assessment would hopefully help to develop a better controlled required for CEIG system, operated in remote areas

A Study of Relationship between Academic Achievement and Mental Health of Secondary School Tribal Students of Assam

The present investigation was undertaken to study the Academic Achievement of secondary school tribal students in relation to their Mental Health. The Researcher had selected 200 secondary school students giving representation to gender and locality. The mental health scale developed by Mercy Abraham and K.C. Baby Prasanna was used as tool and academic achievement scores has taken from school. Pearson’s product moment correlation was applied to find out the relationship and ‘t’ test was applied to find out the significance of difference between different variables. The study found that there is a positive relationship between academic achievement and mental health of secondary school tribal students of Assam. The study also found that there is a significant difference in the mental health of boys and girls, urban and rural secondary school tribal students of Assam

18β-glycyrrhetinic acid triggers curative Th1 response and nitric oxide up-regulation in experimental visceral leishmaniasis associated with the activation of NF-κB

The efficacy of 18β-glycyrrhetinic acid (GRA), a pentacyclic triterpene belonging to the β-amyrin series of plant origin, was evaluated in experimental visceral leishmaniasis. GRA is reported to have antitumor and immunoregulatory activities, which may be attributable in part to the induction of NO. Indeed, an 11-fold increase in NO production was observed with 20 µM GRA in mouse peritoneal macrophages infected with Leishmania donovani promastigotes. In addition to having appreciable inhibitory effects on amastigote multiplication within macrophages (IC50, 4.6 µg/ml), complete elimination of liver and spleen parasite burden was achieved by GRA at a dose of 50 mg/kg/day, given three times, 5 days apart, in a 45-day mouse model of visceral leishmaniasis. GRA treatment resulted in reduced levels of IL-10 and IL-4, but increased levels of IL-12, IFN-γ, TNF-α, and inducible NO synthase, reflecting a switch of CD4+ differentiation from Th2 to Th1. This treatment is likely to activate immunity, thereby imparting resistance to reinfection. GRA induced NF-κB migration into the nucleus of parasite-infected cells and caused a diminishing presence of IκB in the cytoplasm. The lower level of cytoplasmic IκBα in GRA-treated cells resulted from increased phosphorylation of IκBα and higher activity of IκB kinase (IKK). Additional experiments demonstrated that GRA does not directly affect IKK activity. These results suggest that GRA exerts its effects at some level upstream of IKK in the signaling pathway and induces the production of proinflammatory mediators through a mechanism that, at least in part, involves induction of NF-κB activation