Nanostructured Mn oxide particles with an average size of about 7 nm have been prepared by a microemulsion method. X-ray diffraction analysis indicates that the particles possess orthorhombic structure of MnO(OH). The particles are ferromagnetic at low temperature. The Curie temperature is about 35 K and each MnO(OH) molecule generates a magnetic moment of about 0.7 μB. The appearance of the ferromagnetism at low temperature may result from size effect.

The structure and magnetic properties of (Nd 1−x Er x ) 3 Fe 25 Cr 4.0 compounds with x = 0-0.8 have been investigated using x-ray powder diffraction (XRD) and magnetic measurements. It has been found that all the compounds crystallize in a Nd 3 (Fe,Ti) 29 -type structure. Substitution of Er for Nd leads to a contraction of the unit-cell volume. The Curie temperature, T c , and the saturation magnetization, M s , of (Nd 1−x Er x ) 3 Fe 25 Cr 4.0 decrease monotonically with increasing Er content. The easy magnetization direction (EMD) of Nd 3 Fe 25 Cr 4.0 at room temperature is close to the [040] direction but may be a little out of the basal plane. With increasing Er content, the EMD changes closer to the [40−2] direction and the tilt angle increases. Both the XRD patterns and ac susceptibility indicate the appearance of a spin reorientation for x = 0-0.4 as the temperature decreases from room temperature to 77 K. The spin reorientation temperature, T sr , increases monotonically with increasing Er content from 158 K for x = 0 to 198 K for x = 0.4. A first order magnetization process (FOMP) occurs for all the compounds, and the critical field of the FOMP decreases with increasing Er content from 6.6 T for x = 0 to 2.0 T for x = 0.7.

We investigated three coal-bed methane (CBM) reservoirs in which there exist, when we are careful about data quality and reduce environmental variations, inverse correlations between methane content and the elastic properties of the coal beds. Such inverse correlations may exist in general in high- and medium-rank CBM reservoirs. There is evidence that supports the generalization of such inverse correlations and factors that distort them. These distorting factors may prevent identification of such inverse correlations in certain CBM prospects; however, they cannot negate the underlying inverse correlations. Such inverse correlations may play a role in CBM amplitude versus offset (AVO) similar to the role played by Gassmann-Biot theory ( Gassmann, 1951 ; Biot, 1956 , 1962 ) in AVO technology for conventional gas reservoirs. This may lay the first brick for a theoretical basis of CBM AVO.

Using multitemporal remote sensing data from 1987 to 2012, this study extracted the coastlines along the Bohai Sea and explored the relationship between coastline change and human activity. Our results indicate that the general pattern of coastline change can be divided into two stages: a slow-change stage (1987 to 2002) and a rapid-change stage (2002 to 2012). The total area of the Bohai Sea decreased by 1593.44 km 2 from 1987 to 2012, at an average rate of 63.7km 2 ∕year. The total length of coastline along the Bohai Sea increased by 633.7 km at an average rate of 25.3 km∕year. The length of natural coastline decreased by 836.2 km at an average rate of 33.4 km∕year. The length of artificial coastline increased by 1469.9 km, at an average rate of 58.8 km∕year. The artificial coastline composed 27.07% and 74.16% of the total coastline lengths in 1987 and 2012, respectively. The natural coastline was the main coastline type in 1987. However, the natural coastline composed only 25.84% of the total coastline in 2012. The maximum progradation in the Bohai Bay occurred in Caofeidian, where the coastline advanced seaward by ∼19630.33 m, at an average rate of 785.23 m∕year. The maximum erosion occurred at the head of the abandoned Diaokou promontories, where the coastline retreated landward by ∼4758.01 m, at an average rate of 190.33 m∕year. Possible explanations for the coastline changes along the Bohai Sea include natural factors (e.g., riverine sediment supply and hydrodynamic conditions) and human impacts (e.g., reclamation projects), which can be primarily attributed to anthropogenic activities, coastline type, and rapid changes in the Bohai Sea since 2002. The majority of the coastline changes were caused by land reclamation and the construction of embankments. The effects of tides and waves were relatively minimal.

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