Thermoelectric property studies on thallium-doped lead telluride prepared by ball milling and hot pressing

Thallium doping into lead telluride has been demonstrated to increase the dimensionless thermoelectric figure-of-merit (ZT) by enhancing Seebeck coefficient due to the creation of resonant states close to Fermi level without affecting the thermal conductivity. However, the process is tedious, energy consuming, and small in quantities since it involves melting, slow cooling for crystal growth, long time annealing, post-crushing and hot pressing. Here we show that a similar ZT value about 1.3 at 400 °C is achieved on bulk samples with grain sizes of 3–7 μm by ball milling a mixture of elemental thallium, lead, and tellurium and then hot pressing the ball milled nanopowders

Mapping of Hydraulic Fractures Using Tiltmeter Data for Design of EGS Stimulation

ABSTRACT Tiltmeters are widely used in the monitoring of hydraulic fractures, a procedure wherein reservoir rock formations are fractured by the injection of pressurized fluid to enhance well productivity. Tiltmeters measure the fracture induced deformations which can then be inverted to obtain useful fracture parameters. Hydraulic fracturing is now being proposed for stimulation of enhanced geothermal systems in low permeability rock for increased energy extraction. Small scale field sites are proposed as a method to obtain data on the effect of placing multiple hydraulic fractures in an injection well and connecting them to a production well. Fracture growth parameters obtained from tiltmeter mappings at such experiment sites can be used to study the effectiveness of such stimulations. In this work, we propose an approach for the inversion of tilt data using the displacement discontinuity method and the extended Kalman filter. The salient feature of the proposed method is its ability to predict fracture asymmetry with respect to the injection borehole, which is important to know to determine if each stimulation in an array has progressed as expected. This approach uses a forward model based on the analytical solution for computing the displacements and tilts due to a point source displacement discontinuity in an elastic half-space which was developed by Okad

Genome-wide analysis reveals rapid and dynamic changes in miRNA and siRNA sequence and expression during ovule and fiber development in allotetraploid cotton (Gossypium hirsutum L.)

Rapid and dynamic changes in the expression of small RNAs are seen during ovule and fiber development in allotetraploid cotton