Berg and Scherg's fast computation method is extended to multilayer anisotropic spheres. The Berg parameters can be dependent upon a dipole radial parameter or not, depending on the actual sphere conductivities and the layer the dipole is within. To find the Berg parameters, no specific electrode locations are required. Berg and Scherg's method is generally applicable whenever de Munck and Peters's addition-subtraction method can be used.

The Insight-Hard X-ray Modulation Telescope (Insight-HXMT) is a broad band X-ray and gamma-ray (1-3000 keV) astronomy satellite. The High Energy X-ray telescope (HE) is one of its three main telescopes. The main detector plane of HE is composed of 18 NaI(Tl)/CsI(Na) phoswich detectors, where NaI(Tl) serves as primary detector to measure ~ 20-250 keV photons incident from the field of view (FOV) defined by the collimators, and CsI(Na) is used as an active shield detector to NaI(Tl) by pulse shape discrimination. CsI(Na) is also used as an omnidirectional gamma-ray monitor. The HE collimators have a diverse FOV: 1.1°x 5.7° (15 units), 5.7°x 5.7° (2 units) and blocked (1 unit), thus the combined FOV of HE is about 5.7°x 5.7°. Each HE detector has a diameter of 190 mm, resulting in the total geometrical area of about 5100 cm 2 . The energy resolution is ~15% at 60 keV. The timing accuracy is better than 10 μs and dead-time for each detector is less than 10 μs. HE is devoted to observe the spectra and temporal variability of X-ray sources in the 20-250 keV band either by pointing observations for known sources or scanning observations to unveil new sources, and to monitor the gamma-ray sky in 0.2-3 MeV. This paper presents the design and performance of the HE instruments. Results of the on-ground calibration experiments are also reported.

Abstract. The Bayanbulak Grassland, Tianshan, P. R. China, is located in an intramontane sedimentary basin where meandering and braided gravel-bed rivers coexist under the same climatic and geological settings. We report and compare measurements of the discharge, width, depth, slope and grain size of individual threads from these braided and meandering rivers. Both types of threads share statistically indistinguishable regime relations. Their depths and slopes compare well with the threshold theory, but they are wider than predicted by this theory. These findings are reminiscent of previous observations from similar gravel-bed rivers. Using the scaling laws of the threshold theory, we detrend our data with respect to discharge to produce a homogeneous statistical ensemble of width, depth and slope measurements. The statistical distributions of these dimensionless quantities are similar for braided and meandering threads. This suggests that a braided river is a collection of intertwined threads, which individually resemble those of meandering rivers. Given the environmental conditions in Bayanbulak, we furthermore hypothesize that bedload transport causes the threads to be wider than predicted by the threshold theory.

The photoresponsive J-aggregation behaviors of a novel azobenzene-substituted zinc phthalocyanine (azo-ZnPc dyad) were studied by UV/vis, fluorescence, and (1)H NMR spectroscopy. Upon illumination with 365 nm UV light, the trans-cis isomerization of azobenzene can efficiently reduce the steric hindrance around the peripheral oxygen atom of azo-ZnPc, shortening the possible distance between two phthalocyanine molecules and, consequently, greatly improving the tendency of J-aggregation of azo-ZnPc dyad. The third-order optical nonlinearities of the photoresponsive J-aggregates (before and after illumination) were measured by a Z-scan technique at 532 nm with a pulse duration of 25 ps. The Z-scan spectra revealed that all the samples possessed large positive nonlinear refraction and positive nonlinear absorption, exhibiting a self-focusing effect and reverse saturable absorption, respectively. The second molecular hyperpolarizabilities of the dyad in two conditions were measured to be 3.87 x 10(-30) and 4.82 x 10(-30) esu, respectively. All the results suggest that the azo-ZnPc dyad has potential in the field of nonlinear optics applications.

The structural evolution and property changes in Nd 60 Al 10 Fe 20 Co 10 bulk metallic glass ͑BMG͒ upon crystallization are investigated by the ultrasonic method, x-ray diffraction, density measurement, and differential scanning calorimetry. The elastic constants and Debye temperature of the BMG are obtained as a function of annealing temperature. Anomalous changes in ultrasonic velocities, elastic constants, and density are observed between 600-750 K, corresponding to the formation of metastable phases as an intermediate product in the crystallization process. The changes in acoustic velocities, elastic constants, density, and Debye temperature of the BMG relative to its fully crystallized state are much smaller, compared with those of other known BMGs, the differences being attributed to the microstructural feature of the BMG. Recently, many glass forming alloys were discovered. 1,2Previous studies show that the crystallization in various bulk metallic glasses ͑BMGs͒ is characterized by the appearance of intermediate metastable phases. The formation of icosahedral phases as an intermediate product of the crystallization process in BMGs indicates that there is a structural relationship between the BMGs and quasicrystalline.3,4 The Ndbased BMGs have also evoked intensive interests due to their unique magnetic properties and anomalous crystallization behavior. 1,[5][6][7] It is found that the microstructural change induced by relaxation and crystallization has a very sensitive effect on the thermal and magnetic properties of the BMGs. This implies that the hard magnetic property of the BMGs may be related to the formed intermediate phases prior to the crystallization. In this letter, the microstructural and property changes in the Nd 60 Al 10 Fe 20 Co 10 BMG upon crystallization are investigated by using ultrasonic method and density measurement, which are effective and sensitive tools for studying the structural and vibrational characteristics of BMGs. 8-11The structural and property features, prior to and in the crystallization process, are connected.Nd 60 Al 10 Fe 20 Co 10 BMG was prepared by the die casting method. 6 The BMG rod was cut to a length of about 10 mm and its ends were polished flat and parallel. Afterward, the sample was stepwise isothermally annealed at various temperatures for 1.0 h in a vacuum of 10 Ϫ3 Pa, respectively. After each annealing, the rod was cooled to room temperature, and the acoustic velocities and density were measured. The acoustic velocities were measured by a pulse echo overlap method using a MATEC 6600 ultrasonic system with a 10 MHz frequency. 8,9 The density was measured by the Archimedean technique and the accuracy is 0.1%. Elastic constants ͑e.g., Young's modulus E, shear modulus G, bulk modulus K, and Poisson's ratio ͒ and Debye temperature ⌰ D of the BMG were derived from the acoustic velocities and densities. 12 The structure of the samples was characterized by x-ray diffraction ͑XRD͒ using a MAC M03 diffractometer with Cu K␣ radiation. Differential scanning calorimet...