During the period of the Crustal Dynamics Project the accuracy and resolution of Earth orientation measurements both improved by almost two orders of magnitude. These technical advances were accompanied by a corresponding increase in the sophistication of the analysis and interpretation of such data, and by considerable advances in understanding. This paper reviews recent progress in Earth rotation research and assesses the current state of knowledge in the field, concentrating in particular on developments in measurement technology, the theory of orientation changes, and studies of the excitation of rotational variations by irregular fluid motions in the atmosphere, oceans and liquid outer core. 1. INTRODUC7•ON The Crustal Dynamics Project, or CDP [Coates et al., 1985], coincided with a considerable increase in the accuracy and sophistication of Earth rotation research, and had a large role in causing these advances in the field. The CDP was established by the U.S. National Aeronautics and Space Administration (NASA) in 1979, and had as one of its scientific objectives the improvement of "knowledge and understanding of (the) rotational dynamics of the Earth and their possible correlation with earthquakes, plate motions and other geophysical phenomena..." [Coates et al., 1985]. These goals have been substantially met. Space geodetic techniques of unprecedented accuracy and precision have been developed and applied to problems of Earth rotation, to the point that, while at the beginning of the Project variations of Earth rotation with amplitudes of meters and periods of months were just becoming visible (see Figure 1, from Feissel and Gambis [1980]), by the end of the Project (Figure 2) variations with amplitudes of centimeters and periods less than a day are clearly visible [Eubanks et al., 1991b; Brosche et al., 1991; Herring and Dong, 1991; Lichten et ed., 1992; Herring, 1993]. Note the great increase in scale between the two Figures; all of Figure 2 wotfid fit inside one of the asterisks of Figure 1, hadicative of the advance of the state of the art during the lifetime of the Project. The proven causes of Earth rotation changes can be divided into the gravitational interaction between the Earth and other celestial bodies (primarily the Sun and the Moon), and forcings from geophysical fluid dynamics. Geophysical fluid motions tend to have "red" noise power spectra, i.e. to have a general decline in Contributions of Spaco Geodesy to Goodynamics: Earth Dynamics Goodynamics 24 This paper is not subject to U.S. copyright. Published in 1993 by the American Geophysical Union. power with increasing frequency [Agnew, 1992], and increases in the resolution and accuracy of the geodetic data will generally restfit in the detection of smaller motions at higher frequencies. A major thrust of the Project was thus to improve the techniques used to observe rotational variations. Routine determinations of Earth orientation using Very Long Baseline Interferometry (VLBI) [Carter et al., 1985; Robertson et al., 1985a, b; Herring, ...

In this study, a manganese oxide, Mn3O4 was used to remove chromium(III) and chromium(VI) from aqueous solutions. The Mn3O4 nanomaterial was synthesized through a precipitation method, and was characterized using XRD, which confirmed the material had a crystal structure similar to hausmannite. In addition, using Scherrer’s equation it was determined that the nanomaterial had an average grain size of 19.5 ± 1.10 nm. A study of the effects of pH on the binding of chromium(III) and chromium(VI) showed that the optimum binding pH was 4 and 3 respectively. Batch isotherm studies were performed to determine the binding capacity of chromium(III), which was determined to be 18.7 mg/g, 41.7 mg/g, and 54.4 mg/g respectively for 4°C, 21°C, and 45°C. Chromium(VI) on the other hand had lower binding capacities of 2.5 mg/g, 4.3 mg/g, and 5.8 mg/g for 4°C, 21°C, 45°C, respectively. Thermodynamic studies performed indicated the sorption process was for the most part controlled by physisorption. The ΔG for the sorption of chromium(III) and Chromium(VI) ranged from −0.9 to −13 kJ/mol, indicating a spontaneous reaction was occurring. The enthalpy indicated a endothermic reaction was occurring during the binding and show ΔH values of 70.6 and 19.1 kJ.mol for chromium(III) and Chromium(VI), respectively. In addition, ΔS for the reaction had positive values of 267 and 73 J/mol for chromium(III) and chromium(VI) which indicate a spontaneous reaction. In addition, the sorption process was found to follow pseudo second order kinetic and the activation energy studies indicated the binding process occurred through chemisorption.

Poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), Nylon 6, and Nylon 6,6 have been electrospun successfully. The nanofibers have been characterized by scanning electron microscopy (SEM), confirming the presence of bead free and fiber‐bead free morphologies. Thermogravimetric analysis (TGA) indicated differences between the thermal stability of PMMA nanofibers and PMMA powder. However, no significant differences were observed between the starting physical form (powder or pellet) of PVC, Nylon 6 and Nylon 6,6, and their corresponding electrospun nanofibers. Differential scanning calorimetry (DSC) demonstrated a lower glass transition temperature (Tg) and water absorption for PMMA electrospun nanofibers. Furthermore, electrospun Nylon 6 and Nylon 6,6 had a slight decrease in crystallinity. Tensile testing was performed on the electrospun nanofibers to obtain the Young modulus, peak stress, strain at break, and energy to break, revealing that the non‐woven mats obtained had modest mechanical properties that need to be enhanced. Copyright © 2007 John Wiley & Sons, Ltd.

The fabrication of hybrid poly(2,5-bis(2 0ethyl-hexyl)-1,4-phenylenevinylene) (BEH-PPV) and polyethylene oxide (PEO) nanofibers is reported. Nanofibers were created using a novel production method that uses centrifugal rather than electrostatic force to produce nanofibers. The nanofiber production method exhibits high yield production of nanofibers enabling mass-production capabilities. Thermo-physical characterization and X-ray diffraction of bulk PEO and BEH-PPV was conducted, and the results are compared with the produced hybrid nanofibers.

Anomalously high values of atmospheric angular momentum and length of day were observed in late January 1983. This signal in the time series of these two coupled quantities appears to have been a consequence of the equatorial Pacific Ocean warming event of 1982-1983.