Studies on the synthetic, structural, electrical and magnetic properties of Ln(n)MCo(n)O(3n+1) (Ln=Sm, Gd; M=Sr, Ba; n=1,2)

Three new oxides Sm2SrCo2O7, Sm2BaCo2O7 and Gd2SrCo2O7 have been synthesized successfully by solid state reaction mathod. The X-Ray diffraction spectra show that they are all isostructural with Sr3Ti2O7, and Ln(2)SrCo(2)O(7)(Ln=Sm,Gd) crystallized in tetragonal system, Sm2BaCo2O7 in orthrhombic system. The Co-O bonds in CoO2 planes of Ln(2)SrCo(2)O(7) are shorter than those of LnSrCoO(4)(Ln=Sm, Gd), and so their delectrons are more delocalized and their electrical resistivities are smaller. The electrical resistivities versus temperature in the range 300 similar to 1100K showed that the five brides show the characters of weakly localized systems. In the lower temperature range, the magnetic behaviors of Gd2SrCo2O7 and GdSrCoO4 fit Curie-Weiss law well, and the magnetic exchange reaction in CoO2 sublattices of Gd2SrCo2O7 is ferromagnetic, but that of GdSrCoO4 is antiferromagnetic. The other three oxides with Sm3+ showed complex magnetic behaviors which is perhaps related with the complexity of Sm3+.

STUDIES ON THE SYNTHETIC, STRUCTURAL, ELECTRICAL, AND MAGNETIC-PROPERTIES OF THE NEW LAYERED OXIDES LN(2)MCO(2)O(7) (LN=SM, GD, M=SR, BA)

Three new oxides Ln(2)MCo(2)O(7) (Ln = Sm, Gd; M = Sr, Ba) have been synthesized in solid state reaction method. The powder X-ray diffraction spectra show that they are all isostructural with Sr3Ti2O7. The electrical resistivities in the temperature range 300-1100 K show that they are all semiconductors, and a transition to metals is observed at 1053, 1053, and 573 K for Sm2SrCo2O7, Gd2SrCo2O7, and Sm2BaCo2O7, respectively. The magnetic suspectivities of Gd2SrCo2O7 in the temperature range 300-673 K fit the Curie-Weiss law well. A plateau is observed in the curves of Sm(2)MCo(2)O(7) (M = Sr, Ba) which is attributed to the configuration state change of Co(III) from low spin to high spin. (C) 1995 Academic Press, Inc.

THE PHYSICAL AND CHEMICAL-PROPERTIES OF SYNTHETIC AND NATURAL JADEITE FOR JEWELRY

Jadeite was synthesized from its glass of stoichiometric composition NaAlSi2O6, and a colouring agent Cr2O3 (0.3-0.6 wt%) was added to achieve the emerald colour. The conditions employed were a pressure range of 3.0-5.0 GPa and a temperature range of 1150

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .1. SULFONATION OF PPO AND CHARACTERIZATION OF THE PRODUCTS

Poly(2,6-dimethylphenylene oxide) (PPO) was sulfonated to varying degrees using different sulfonating agents. Physical properties such as solubility, density, and thermal properties were studied for both PPO and sulfonated PPO (SPPO) with different degree

Diterpenes, sesquiterpenes, and a C-15-acetogenin from the marine red alga Laurencia mariannensis

In addition to 10 known compounds (7-16), one new brominated diterpene, 10-hydroxykahukuene B (1), two new sesquiterpenes, 9-deoxyelatol (2) and isodactyloxene A (3), one new brominated C-15-acetogenin, laurenmariallene (4), and two new naturally occurring halogenated sesquiterpenes (5 and 6) that were previously obtained as intemediates in a biomimetic synthetic study of rhodolaureol and rhodolauradiol have been isolated and identified from the organic extract of the marine red alga Laurencia mariannensis. The structures of these compounds were established by spectroscopic methods. The antibacterial and antifungal activities of new compounds 1-4 were evaluated.

Species identification in salted products of red snappers by semi-nested PCR-RFLP based on the mitochondria 12S rRNA gene sequence

A molecular approach was developed to distinguish species of red snappers among commercial salted fish products. The specific fragments of the mitocliondrial 12S rRNA gene, which were about 450 bp, were obtained using the semi-nested polymerase chain reaction (semi-nested PCR). Subsequently, PCR amplicons were sequenced, aiming to select restriction endonucleases that generated species-specific restriction fragment length polymorphism (RFLP) profiles. Discrimination of red snappers Lutjanus sanguineus, L. erythopterus from L. argentintaculatus, L. malabarius and other morphologically similar fishes such as Lethrinus leutjanus and Pinjalo pinjalo was feasible by one restriction digestion reaction with three endonucleases Hae III, Sca I and SnaB I, however, for differentiation of L. sattguineus and L. erythopterus, another restriction digestion reaction with single restriction endonuclease Mae II was needed. The seminested PCR-RFLP was demonstrated to be reliable in species identification of salted fish products in this study. (c) 2005 Published by Elsevier Ltd.

Species identification in salted products of red snappers by semi-nested PCR-RFLP based on the mitochondrial 12S rRNA gene sequence

A molecular approach was developed to distinguish species of red snappers among commercial salted fish products. The specific fragments of the mitochondrial 12S rRNA gene, which were about 450bp, were obtained using the semi-nested polymerase chain reaction (semi-nested PCR). Subsequently, PCR arnplicons were sequenced, aiming to select restriction endonucleases that generated species-specific restriction fragment length polymorphism (RFLP) profiles. Discrimination of red snappers Lutjanus sanguineus, Lutjanus erythopterus from Lutjanus argentimaculatus, Lutjanus malabarius and other morphologically similar fishes such as Lethrinus leutjanus and Pinjalo pinjalo was feasible by one restriction digestion reaction with three endonucleases Hae III, Sca I and SnaB I, however, for discrimination of L. sanguineus and L. erythopterus, another restriction digestion reaction with single restriction endonuclease Mae II was needed. The semi-nested PCR-RFLP was demonstrated to be reliable in species identification of salted fish products in this study. (c) 2005 Elsevier Ltd. All rights reserved.

Remote sensing of ocean waves by along-track interferometric synthetic aperture radar

A new wave retrieval method for the Along-Track Interferometric Synthetic Aperture Radar (AT-InSAR) phase image is presented. The new algorithm, named parametric retrieval algorithm (PRA), uses the full nonlinear mapping relations. It differs from previous retrieval algorithms in that it does not require a priori information about the sea state or the wind vector from scatterometer data. Instead, it combines the observed AT-InSAR phase spectrum and assumed wind vector to estimate the wind sea spectrum. The method has been validated using several C-band and X-band HH-polarized AT-InSAR observations collocated with spectral buoy measurements. In this paper, X-band and C-band HH-polarized AT-InSAR phase images of ocean waves are first used to study AT-InSAR wave imaging fidelity. The resulting phase spectra are quantitatively compared with forward-mapped in situ directional wave spectra collocated with the AT-InSAR observations. Subsequently, we combine the parametric retrieval algorithm (PRA) with X-band and C-band HH-polarized AT-InSAR phase images to retrieve ocean wave spectra. The results show that the ocean wavelengths, wave directions, and significant wave heights estimated from the retrieved ocean wave spectra are in agreement with the buoy measurements.

On the nonlinear integral transform of an ocean wave spectrum into an along-track interferometric synthetic aperture radar image spectrum

We present a new nonlinear integral transform relating the ocean wave spectrum to the along-track interferometric synthetic aperture radar (AT-INSAR) image spectrum. The AT-INSAR, which is a synthetic aperture radar (SAR) employing two antennas displaced along the platform's flight direction, is considered to be a better instrument for imaging ocean waves than the SAR. This is because the AT-INSAR yields the phase spectrum and not only the amplitude spectrum as with the conventional SAR. While the SAR and AT-INSAR amplitude spectra depend strongly on the modulation of the normalized radar cross section (NRCS) by the long ocean waves, which is poorly known, the phase spectrum depends only weakly on this modulation. By measuring the phase difference between the signals received by both antennas, AT-INSAR measures the radial component of the orbital velocity associated with the ocean waves, which is related to the ocean wave height field by a well-known transfer function. The nonlinear integral transform derived in this paper differs from the one previously derived by Bao et al. [1999] by an additional term containing the derivative of the radial component of the orbital velocity associated with the long ocean waves. By carrying out numerical simulations, we show that, in general, this additional term cannot be neglected. Furthermore, we present two new quasi-linear approximations to the nonlinear integral transform relating the ocean wave spectrum to the AT-INSAR phase spectrum.

A parametric method of retrieving ocean wave spectra from synthetic aperture radar images

A parametric method that extracts the ocean wave directional spectra from synthetic aperture radar (SAR) image is presented. The 180 degrees ambiguity of SAR image and the loss of information beyond the azimuthal cutoff can be overcome with this method. The ocean wave spectra can be obtained from SAR image directly by using iteration inversion mapping method with forward nonlinear mapping. Some numerical experiments have been made by using ERS-1 satellite SAR imagette data. The ocean wave direction retrieved from SAR imagette data is in agreement with the wind direction from the scatterometer data.

Numerical simulation and validation of ocean waves measured by an Along-Track Interferometric Synthetic Aperture Radar

A new nonlinear integral transform of ocean wave spectra into Along-Track Interferometric Synthetic Aperture Radar (ATI-SAR) image spectra is described. ATI-SAR phase image spectra are calculated for various sea states and radar configurations based on the nonlinear integral transform. The numerical simulations show that the slant range to velocity ratio (R/V), significant wave height to ocean wavelength ratio (H-s/lambda), the baseline (2B) and incident angle (theta) affect ATI-SAR imaging. The ATI-SAR imaging theory is validated by means of Two X-band, HH-polarized ATI-SAR phase images of ocean waves and eight C-band, HH-polarized ATI-SAR phase image spectra of ocean waves. It is shown that ATI-SAR phase image spectra are in agreement with those calculated by forward mapping in situ directional wave spectra collected simultaneously with available ATI-SAR observations. ATI-SAR spectral correlation coefficients between observed and simulated are greater than 0.6 and are not sensitive to the degree of nonlinearity. However, the ATI-SAR phase image spectral turns towards the range direction, even if the real ocean wave direction is 30 degrees. It is also shown that the ATI-SAR imaging mechanism is significantly affected by the degree of velocity bunching nonlinearity, especially for high values of R/V and H-s/lambda.

Synthesis and evaluation of a thiourea-modified chitosan derivative applied for adsorption of Hg(II) from synthetic wastewater

In this work, a thiourea-modified chitosan derivative (TMCD) was synthesized through two steps, O-carboxymethylated first and then modified by a polymeric Schiff's base of thiourea/glutaraldehyde. The adsorption behavior of mercury (II) ions onto TMCD was investigated through batch method. The maximum adsorption capacity for Hg(II) was found to be 6.29 mmol/g at pH 5.0 and both kinetic and thermodynamic parameters of the adsorption process were obtained. The results indicated that adsorption process was spontaneous exothermic reaction and kinetically followed pseudo-second-order model. The adsorption experiments also demonstrated TMCD had high adsorption selectivity towards Hg(II) ions when coexisted with Cu(II), Zn(II), Cd(II) and Ca(II) in solution and it could be easily regenerated and efficiently reused. (C) 2010 Elsevier B.V. All rights reserved.

Formation of nano-crystalline corrosion products on Zn-Al alloy coating exposed to seawater

Hot dip Zn-Al alloy coating performs better than hot dip galvanized coating and 55% Al-Zn-Si coating as well with regard to general seawater corrosion protection. A characterization of the corrosion products on Zn-Al alloy coating immersed in dynamic aerated seawater has been performed mainly based on transmission electron microscopy (TEM) for morphological analysis and X-ray diffraction (XRD) technique for crystalline phase identification. The XRD and TEM analyses showed that the corrosion products mainly were typical nanometer Zn4CO3(OH)(6).H2O, Zn-5(OH)(8)Cl-2 and Zn6Al2CO3(OH)(16). 4H(2)O microcrystals. This probably is connected to the co-precipitation of Zn2+ and Al3+ ions caused by adsorption. Zn-Al alloy coating being suffered seawater attacks, AI(OH)(3) gel was first produced on the coating surface. Zn and Al hydroxides would co-precipitate and form double-hydroxide when the concentration of adsorbed Zn2+ ions by the newly produced gel exceeded the critical degree of supersaturation of the interphase nucleation. However, because the growth of the crystals was too low to keep in step with the nucleation, a layer of nano-crystalline corrosion products were produced on the surface of the coating finally. (C) 2001 Elsevier Science Ltd. All rights reserved.

Electrochemical and thermodynamic investigation of diniconazole and triadimefon as corrosion inhibitors for copper in synthetic seawater

This paper presents the investigation of diniconzole and triadimefon as chemical corrosion inhibitors for freshly polished copper in synthetic seawater (3.5% NaCl solution). Determination of weight loss, polarization curves, electrochemical impedance spectroscopy (EIS), and SEM, were performed to analyze the inhibiting performance of these compounds. Polarization curves show that they act as mixed-type inhibitors. EIS indicates that an adsorption film of the inhibitors is formed on copper surface. The highest values of inhibition efficiency are respectively, 99.2% and 97.3% at 100 mg/L concentration. Thermodynamic calculation suggests that chemisorptions between the compounds and copper are accordance with Langmuir adsorption isotherm. (C) 2010 Elsevier Ltd. All rights reserved.