Exploring the possibility of enhancing the figure-of-merit ( >> 2) of Na0.74_{0.74}CoO2_{2}: A combined experimental and theoretical study

Search of new thermoelectric (TE) materials with high \textit{figure-of-merit} (ZT) is always inspired the researcher in TE field. Here, we present a combined experimental and theoretical study of TE properties of Na$_{0.74}$CoO$_{2}$ compound in high-temperature region. The experimental Seebeck coefficient (S) is found to vary from 64 to 118 $\mu$V/K in the temperature range $300-620$ K. The positive values of S are indicating the dominating p-type behaviour of the compound. The observed value of thermal conductivity ($\kappa$) is $\sim$ 2.2 W/m-K at 300 K. In the temperature region $300-430$ K, the value of $\kappa$ increases up to $\sim$ 2.6 W/m-K and then decreases slowly till 620 K with the corresponding value of $\sim$ 2.4 W/m-K. We have also carried out the theoretical calculations and the best matching between experimental and calculated values of transport properties are observed in spin-polarized calculation within DFT+\textit{U} by chosen \textit{U} = 4 eV. The maximum calculated value of ZT is found to be $\sim$ 0.67 at 1200 K for p-type conduction. Our computational study suggests that the possibility of n-type behaviour of the compound which can lead to a large value of ZT at higher temperature region. Electron doping of $\sim$ 5.1$\times$10$^{20}$ cm$^{-3}$ is expected to give rise the high ZT value of $\sim$ 2.7 at 1200 K. Using these temperature-dependent ZT values, we have calculated the maximum possible values of efficiency ($\eta$) of thermoelectric generator (TEG) made by p and n-type Na$_{0.74}$CoO$_{2}$. The present study suggests that one can get the efficiency of a TE cell as high as $\sim$ 11$\%$ when the cold and hot end temperature are fixed at 300 K and 1200 K, respectively. Such high values of ZT and efficiency suggest that Na$_{0.74}$CoO$_{2}$ can be used as a potential candidate for high-temperature TE applications

Agricultural growth linkages in Sub-Saharan Africa:

How much extra net income growth can be had in rural areas of Africa by increasing the spending power of local households? The answer depends on how rural households spend increments to income, whether the items desired can be imported to the local area in response to increased demand, and, if not, whether increased demand will lead to new local production or simply to price rises. For every dollar in new farm income earned, at least one additional dollar could be realized from growth multipliers, according to Agricultural Growth Linkages in Sub-Saharan Africa.Income Rural areas Africa., Agricultural development Africa., Agricultural policy Economic aspects., Households Zimbabwe., Social accounting., Africa sub-Saharan,

Biomarkers for Radiation Pneumonitis Using Noninvasive Molecular Imaging

Our goal is to develop minimally invasive biomarkers for predicting radiation-induced lung injury before symptoms develop. Currently, there are no biomarkers that can predict radiation pneumonitis. Radiation damage to the whole lung is a serious risk in nuclear accidents or in radiologic terrorism. Our previous studies have shown that a single dose of 15 Gy of x-rays to the thorax causes severe pneumonitis in rats by 6–8 wk. We have also developed a mitigator for radiation pneumonitis and fibrosis that can be started as late as 5 wk after radiation. Methods: We used 2 functional SPECT probes in vivo in irradiated rat lungs. Regional pulmonary perfusion was measured by injection of 99mTc-macroaggregated albumin. Perfused volume was determined by comparing the volume of distribution of 99mTc-macroaggregated albumin to the anatomic lung volume obtained by small-animal CT. A second probe, 99mTc-labeled Duramycin, which binds to apoptotic cells, was used to measure pulmonary cell death in the same rat model. Results: The perfused volume of lung was decreased by about 25% at 1, 2, and 3 wk after receipt of 15 Gy, and 99mTc-Duramycin uptake was more than doubled at 2 and 3 wk. There was no change in body weight, breathing rate, or lung histology between irradiated and nonirradiated rats at these times. Pulmonary vascular resistance and vascular permeability measured in isolated perfused lungs ex vivo increased at 2 wk after 15 Gy of irradiation. Conclusion: Our results suggest that SPECT biomarkers have the potential to predict radiation injury to the lungs before substantial functional or histologic damage is observed. Early prediction of radiation pneumonitis in time to initiate mitigation will benefit those exposed to radiation in the context of therapy, accidents, or terrorism

Effect of an extract of Centella asiatica on the biodistribution of sodium pertechnetate (Na^99mTcO₄) and on the fixation of radioactivity on blood constituents

This study evaluates the effects of an acute treatment with a Centella asiatica (CA) extract on the biodistribution of the radiopharmaceutical Na99mTcO4 and on the fixation of technetium-99m on blood constituents. Wistar rats were treated with CA extract and, 1 hour after, Na99mTcO4 was administered; organs/tissues were withdrawn and weighted. The radioactivity was counted to calculate the percentage of activity per gram (%ATI/g). Also, blood samples were withdrawn, plasma (P), blood cells (BC), insoluble fraction (IF) and soluble fractions of P and BC were isolated and the radioactivity was counted to calculate the percentage of activity (%ATI). Data indicated that the acute treatment with CA extract changed significantly (p99mTcO4 and the fixation of the technetium-99m on blood constituents in an acute treatment

Dynamical Evolution of Boson Stars II: Excited States and Self-Interacting Fields

The dynamical evolution of self-gravitating scalar field configurations in numerical relativity is studied. The previous analysis on ground state boson stars of non-interacting fields is extended to excited states and to fields with self couplings. Self couplings can significantly change the physical dimensions of boson stars, making them much more astrophysically interesting (e.g., having mass of order 0.1 solar mass). The stable ($S$) and unstable ($U$) branches of equilibrium configurations of boson stars of self-interacting fields are studied; their behavior under perturbations and their quasi-normal oscillation frequencies are determined and compared to the non-interacting case. Excited states of boson stars with and without self-couplings are studied and compared. Excited states also have equilibrium configurations with $S$ and $U$ branch structures; both branches are intrinsically unstable under a generic perturbation but have very different instability time scales. We carried out a detailed study of the instability time scales of these configurations. It is found that highly excited states spontaneously decay through a cascade of intermediate states similar to atomic transitions.Comment: 16 pages+ 13 figures . All figures are available at http://wugrav.wustl.edu/Paper

Development of Hand-Operated Mechanical Ginger Peeler

Ginger, an underground rhizome, is valued as a spice and is used in both dry and fresh form. The process of peeling is labour-intensive and is a time-consuming operation in post-harvest handling of ginger done manually by women labour. To reduce time and labour requirement, a mechanical ginger peeler having a square mesh drum was developed. Peeling trials were conducted for varying drum loads (6kg, 8kg and 10kg), varying drum speeds (35rpm, 40rpm and 45rpm) and for different peeling durations (5 min, 10 min and 15 min). Optimum machine parameters for maximum efficiency were: drum load of 8 kg per batch, operated at drum speed of 40rpm for peeling duration 15 min. Peeling efficiency and material loss at optimum conditions were determined to be 55.60% and 4.68%, respectively. Dry ginger obtained after mechanical peeling was found to contain essential oil at 2%, oleoresin 4.6%, moisture content 9.82% and crude fibre content 2.5%

Development of a hand operated diamond cut mesh drum abrasive ginger peeler

Peeling of fresh ginger is an important operation done before drying to enhance the drying process and is generally done manually. A mechanical ginger peeler was developed with its peeling drum made of diamond cut mesh. Peeling trials were conducted for varying drum loads (5 kg, 6 kg and 7 kg), for varying drum speeds (20 rpm, 25 rpm and 30 rpm) and for different peeling durations (5 m, 10 m and 15 m) to determine the peeling efficiency and material loss in the developed peeler. It was found that peeling of ginger was associated with the material loss. The optimum machine parameters for maximum peeling with minimum loss was obtained at a drum load of 7 kg per batch, operated at a drum speed of 30 rpm for a peeling duration of 15 min, to produce sufficiently peeled ginger. The peeling efficiency and material loss at the optimum conditions were determined as 59.43% and 4.76%, respectively. The ginger obtained after mechanical peeling was dried and the quality was determined. It was found to have essential oil of 2.0%, oleoresin of 4.6%, moisture content of 9.82% and crude fibre content of 2.5%. &nbsp

Physical and biochemical parameters of fresh and dry ginger (Zingiber officinale Roscoe)

The physical and biochemical properties of fresh and dry ginger (Zingiber officinale) (cv: Himachal) obtained from Nemmara (Palakkad District, Kerala), useful for the design of processing machineries, were determined. The average moisture content of fresh and dry rhizomes were 81.70% and 8.85%, respectively. The average length, width and thickness of fresh rhizome were 14.99 cm, 8.17 cm and 4.49 cm, respectively and the corresponding values for dry rhizome were 9.74 cm, 5.56 cm and 4.49 cm. The mean values of cylindricity for primary, secondary and tertiary finger rhizomes were 0.46, 0.51 and 0.56, respectively and the corresponding values for dry finger rhizomes were 0.48, 0.53 and 0.58. The average mass, volume and surface area of fresh rhizomes were 103.45 g, 85.0 cm3 and 194.52 cm2, respectively and the corresponding values for dry rhizomes were 31.62 g, 22.10 cm3 and 65.84 cm2. The bulk density, true density and porosity for fresh rhizomes were determined as 471.49 kg m-3, 1107.01 kg m-3 and 66.80%, respectively, and for dry rhizomes the values were 460.09 kg m-3, 1013.22 kg m-3 and 54.09%. The angle of repose increased from 34.6° to 39.5° after drying. Mild steel surface offered more frictional resistance than other surfaces and the coefficient of friction for fresh and dry ginger against mild steel was 0.74 and 0.54, respectively. The average meat : peel ratio of the whole fresh rhizome was 10.7:1. The average recovery of dry ginger was 23.01%. The dry ginger obtained had 1.6% essential oil, 3.5% oleoresin and 2.7% crude fibre. &nbsp