Grain size effects on charge-ordering, phase segregation and related properties of rare-earth manganates, Nd(0.5)A(0.5)MnO(3) (A = Ca or Sr)

Grain size has marked effects on charge-ordering and other properties of Nd(0.5)A(0.5)MnO(3) (A=Ca or Sr). Thus, the anti-ferromagnetic (AFM) transition in Nd0.5Ca0.5MnO3 is observed distinctly only in samples sintered at 1273 K or higher. The sample with a small grain size (sintered at 1173 K) shows evidence for greater ferromagnetic (FM) interaction at low temperatures, probably due to phase segregation. The FM transition as well as the charge-ordering transition in Nd0.5Sr0.5MnO3 becomes sharper in samples sintered at 1273 K or higher. The sample sintered at 1173 K does not show the AFM-CO transition around 150 K and is FM down to low temperatures; the apparent T-c-T-co gap decreases with the increase in the grain size. The samples sintered at lower temperatures (<1673 K) show evidence for greater segregation of the AFM and FM domains. (C) 2002 Elsevier Science Ltd. All rights reserved.

Complexes of rare-earth perchlorates with ditbutyl amides of di, tri and tetraglycolic acids

New complexes of lanthanide perchlorates with di-t-butyl amides of di, tri and tetraglycolic acids have been synthesised. The complexes have the general formula Ln(DiGA)3(ClO4)3; Ln(TriGA)2 (ClO4)3 and Ln(TetGA)2 (C1O4)3, where Ln = La-Yb and Y and DiGA = N,N′, di-t-butyl diglycolamide, TriGA N,N′, di-t-butyl triglycolamide and TetGA = N,N′ di-t-butyl tetraglycolamide, respectively. The complexes have been characterized by analysis, electrolytic conductance, infrared,1H and13C nuclear magnetic resonance and electronic spectral data.Infrared spectra indicate the coordination of all the available ether oxygens and the amide carbonyls in each of the ligands, to the metal ions. IR and conductance data show that the perchlorate groups in all the complexes are ionic.1H and13C NMR data support the IR data regarding the mode of coordination of ligands to the metal ions. Electronic spectral shapes have been interpreted in terms of nine, eight and ten coordination in DiGA, TriGA and TetGA complexes respectively.

Gibbs energies of formation of rare earth MPt5 compounds

The Gibbs energies of formation of MPt5 (MNd, Dy, Ho, Er) intermetallic compounds were determined in the temperature range 900–1100 K using the solid state cell Ta,M+MF3¦CaF2¦MPt5+Pt+MF3,Ta For M ≡ Sm, a mixture of Gd + GdF3 was used as the reference electrode. In the case of Eu, a mixture of Eu + EuF2 served as the reference electrode. The trifluorides of Sm and Eu are not stable in equilibrium with the metal. The fluoride phase coexisting with a SmPt5 + Pt mixture is SmF3, whereas EuF2 is the equilibrium phase in contact with EuPt5 + Pt. All the MPt5 compounds studied (except EuPt5) exhibit similar stability. Europium is divalent in the pure metal and trivalent in EuPt5. The energy required for the promotion of divalent Eu to the trivalent state accounts for the less negative Gibbs energy of formation of EuPt5. The enthalpies of formation of all the MPt5 compounds obtained in this study are in good agreement with Miedema's model.

Measurement of probability-distribution functions sensitive technique for the study of conduction phenomena in liquid dielectrics

The paper outlines a technique for sensitive measurement of conduction phenomena in liquid dielectrics. The special features of this technique are the simplicity of the electrical system, the inexpensive instrumentation and the high accuracy. Detection, separation and analysis of a random function of current that is superimposed on the prebreakdown direct current forms the basis of this investigation. In this case, prebreakdown direct current is the output data of a test cell with large electrodes immersed in a liquid medium subjected to high direct voltages. Measurement of the probability-distribution function of a random fluctuating component of current provides a method that gives insight into the mechanism of conduction in a liquid medium subjected to high voltages and the processes that are responsible for the existence of the fluctuating component of the current.

An inventory of the ethnobotanicals used as anti-diabetic by a rural community of Dhemaji district of Assam, Northeast India

Ethnopharmacological relevance: Traditional remedies used for treating diabetic ailments are very important in the primary health care of the people living in rural Dhemaji district of Assam, north-east India. Novel information gathered from the current survey is important in preserving folk indigenous knowledge. Materials and methods: Interviews were conducted amongst 80 households comprising of 240 individuals using semi-structured questionnaires. The focus was on plants used in treating diabetes mellitus. Results: The current survey documented 21 plant species (20 families) which are reportedly used to treat diabetes mellitus by the rural people in the study area. To the best of our knowledge, Amomum linguiforme, Cinnamomum impressinervium, Colocasia esculenta, Dillenia indica, Euphorbia ligularia, Garcinia pedunculata, Solanum indicum, Sterculia villosa and Tabernaemontana divaricata are recorded for the first time based on globally published literature as medicinal plants used for treating diabetes mellitus and related symptoms. Conclusions: The wide variety of plants that are used to treat diabetes mellitus in this area supports the traditional value that medicinal plants have in the primary health care system of the rural people of Dhemaji district of Assam. The finding of new plant uses in the current study reveals the importance of the documentation of such ethnobotanical knowledge. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Study of surface oxidation of rare-earth-metals by photoelectron-spectroscopy

Surface oxidation of La, Ce, Sm and Tb metals has been investigated by He(II) ultraviolet photoelectron spectroscopy (u.p.s.) and X-ray photoelectron spectroscopy (X.p.s.). Oxidation of La gives rise to La2O3 on the surface. While Ce2O3 appears to be the stable oxide on the surface, we find evidence for formation of CeO2 at high oxygen exposure. Valence band of Sm clearly shows the presence of both divalent and trivalent states due to interconfigurational fluctuation. Exposure of Sm to oxygen first depletes the divalent Sm at the surface. While Sm2O3 is the stable oxide on the surface of Sm, Tb2O3 is the stable oxide on the surface of Tb (and not any of the higher oxides).

Sensitivity of nucleation phenomena on range of interaction potential

Theoretical and computational investigations of nucleation have been plagued by the sensitivity of the phase diagram to the range of the interaction potential. As the surface tension depends strongly on the range of interaction potential and as the classical nucleation theory (CNT) predicts the free energy barrier to be directly proportional to the cube of the surface tension, one expects a strong sensitivity of nucleation barrier to the range of the potential; however, CNT leaves many aspects unexplored. We find for gas-liquid nucleation in Lennard-Jones system that on increasing the range of interaction the kinetic spinodal (KS) (where the mechanism of nucleation changes from activated to barrierless) shifts deeper into the metastable region. Therefore the system remains metastable for larger value of supersaturation and this allows one to explore the high metastable region without encountering the KS. On increasing the range of interaction, both the critical cluster size and pre-critical minima in the free energy surface of kth largest cluster, at respective kinetic spinodals, shift towards smaller cluster size. In order to separate surface tension contribution to the increase in the barrier from other non-trivial factors, we introduce a new scaling form for surface tension and use it to capture both the temperature and the interaction range dependence of surface tension. Surprisingly, we find only a weak non-trivial contribution from other factors to the free energy barrier of nucleation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3685835]

The Contribution of Rare Species to Community Phylogenetic Diversity across a Global Network of Forest Plots

Niche differentiation has been proposed as an explanation for rarity in species assemblages. To test this hypothesis requires quantifying the ecological similarity of species. This similarity can potentially be estimated by using phylogenetic relatedness. In this study, we predicted that if niche differentiation does explain the co-occurrence of rare and common species, then rare species should contribute greatly to the overall community phylogenetic diversity (PD), abundance will have phylogenetic signal, and common and rare species will be phylogenetically dissimilar. We tested these predictions by developing a novel method that integrates species rank abundance distributions with phylogenetic trees and trend analyses, to examine the relative contribution of individual species to the overall community PD. We then supplement this approach with analyses of phylogenetic signal in abundances and measures of phylogenetic similarity within and between rare and common species groups. We applied this analytical approach to 15 long-term temperate and tropical forest dynamics plots from around the world. We show that the niche differentiation hypothesis is supported in six of the nine gap-dominated forests but is rejected in the six disturbance-dominated and three gap-dominated forests. We also show that the three metrics utilized in this study each provide unique but corroborating information regarding the phylogenetic distribution of rarity in communities.

Interim report on the progress of an inventory of artesian wells in Florida: leading to the enforcement of sections 370.051 - 370.54, Florida statues

One of the causes of lower artesian pressure, water waste and aquifer contamination is the misuse and insufficient care of artesian wells. In 1953, Senate Bill No. 57, entitled "An Act to Protect and Control the Artesian Waters of the State" (see Appendix) became a law. This law was passed through the efforts exerted by leading members of the Senate and the House of Representatives, who understood the need for a wise and controlled expenditure of our most valuable natural resource. The State Geologist and his authorized representatives were designated by this law to enforce this conservation measure; however, no financial provision was included for the 1953-55 biennium. The proposed program of the Florida Geological Survey for this biennium did not include the funds nor provide any full-time personnel for the enforcement of this statute. As a result, little actual work was accomplished during these two years, although much time was given to planning and discussion of the problem. Realizing that this program could provide additional basic data needed in the analysis of the water-supply problem, the State Geologist sought and was granted by the 1955 Legislature adequate funds with which to activate the first phase of the enforcement of Florida Statute No. 370.051-054. Enumerated below is a summary of the progress made on this investigation as outlined previously: 1. Data have been collected on 967 wildly flowing wells in 22 counties. 2. Chloride determinations have been run on 850 of the 967 wells. 3. Of the 967 wells, 554 have chlorides in excess of the 250 ppm, the upper limit assigned by the State Board of Health for public consumption. 4. Water escapes at the rate of 37, 762 gallons per minute from these 967 wells. This amounts to 54, 377, 280 gallons per day. The investigation is incomplete at this time; therefore, no final conclusions can be reached. However, from data already collected, the following recommendations are proposed: 1. That the present inventory of wildly flowing wells be completed for the entire State. 2. That the current inventory of wildly flowing wells be expanded at the conclusion of the present inventory to include all flowing wells. 3. That a complete statewide inventory program be established and conducted in cooperation with the Ground Water Branchof the U.S. Geological Survey. 4. That the enforcement functions as set down in Sections 370.051/.054, Florida Statutes, be separated from the program to collect water-resource data and that these functions be given to the Water Resources Department, if such is created (to be recommended by the Water Resources Study Commission in a water policy law presented to the 1957 Legislature). 5. That the research phase (well inventory) of the program remain under the direction of the Florida Geological Survey. (PDF contains 204 pages.)

Final report on an inventory of flowing artesian wells in Florida: leading to the enforcement of sections 373.021 - 373.061 Florida Statutes 1957

This report published as Information Circular No. 21, together with the interim report published in 1957 as Information Circular No. 10, Florida Geological Survey, illustrates as completely as possible the situation that now exists among the freely flowing wells of the State. (PDF contains 40 pages.)

Residential Docks and Piers: Inventory of laws, regulations, and policies for the New England region

While the homes threatened by erosion and the developer illegally filling in marshlands are the projects that make the headlines, for many state regulatory programs, it’s the residential docks and piers that take up the most time. When is a dock too long? What about crossing extended property lines? And at what point does a creek have too many docks? There are no easy answers to these questions. At the request of the Georgia Coastal Management Program, the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center published in April 2003 an inventory of residential dock and pier management information for the southeastern U.S. This inventory builds upon that effort and includes five New England states and one municipality: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and the Town of Falmouth, Massachusetts. Federal laws, state laws and regulations, permitting policies, and contact information are presented in a tabular format that is easy to use. (PDF contains 16 pages)