Large magnetoresistance anomalies in Dy7Rh3

The compound Dy7Rh3 ordering antiferromagnetically below (TN=) 59 K has been known to exhibit a temperature (T) dependent electrical resistivity (rho) behavior in the paramagnetic state unusual for intermetallic compounds in the sense that there is a broad peak in rho(T) in the paramagnetic state (around 130 K) as though there is a semi-conductor to metal transition. In addition, there is an upturn below T_N due to magnetic super-zone gap effects. Here we report the influence of external magnetic field (H) on the rho(T) behavior of this compound below 300 K. The rise of rho(T) found below TN could be suppressed at very high fields (>> 60 kOe), thus resulting in a very large magnetoresistance (MR) in the magnetically ordered state. The most notable finding is that the magnitude of MR is large for moderate applications of H (say 80 kOe) in a temperature range far above T_N as well, which is untypical of intermetallic compounds. Thus, this compound is characterized by large MR anomalies in the entire T range of investigation.Comment: IOP Selec

Getter sputtering system for high-throughput fabrication of composition spreads

We describe a sputtering system that can deposit composition spreads in an effectively UHV environment but which does not require the high-throughput paradigm to be compromised by a long pump down each time a target is changed. The system deploys four magnetron sputter guns in a cryoshroud (getter sputtering) which allows elements such as Ti and Zr to be deposited with minimal contamination by oxygen or other reactive background gases. The system also relies on custom substrate heaters to give rapid heating and cool down. The effectiveness of the gettering technique is evaluated, and example results obtained for catalytic activity of a pseudoternary composition spread are presented

Getter sputtering system for high-throughput fabrication of composition spreads

We describe a sputtering system that can deposit composition spreads in an effectively UHV environment but which does not require the high-throughput paradigm to be compromised by a long pump down each time a target is changed. The system deploys four magnetron sputter guns in a cryoshroud (getter sputtering) which allows elements such as Ti and Zr to be deposited with minimal contamination by oxygen or other reactive background gases. The system also relies on custom substrate heaters to give rapid heating and cool down. The effectiveness of the gettering technique is evaluated, and example results obtained for catalytic activity of a pseudoternary composition spread are presented

Comparative Ultrastructure Of Digestive Diverticulae In Bathymodiolin Mussels: Discovery Of An Unknown Spherical Inclusion (Six) In Digestive Cells Of A Seep Mussel

Mussels in the genus Bathymodiolus host endosymbiotic bacteria in their gills, from which the mussel derives much of its nutrition. Bathymodiolin mussels also have functional digestive systems and, as in shallow-water mytilid mussels, cells of the digestive diverticulae are of two types: basophilic secretory cells and columnar digestive cells. Cellular contents of secretory and digestive cells of Bathymodiolus thermophilus and Bathymodiolus brevior from deep-sea hydrothermal vents are comparable to cellular contents of these cell types observed in shallow-water mytilids. In the seep mussel Bathymodiolus heckerae, cellular contents of columnar cells were anomalous, being dominated by an unknown cellular inclusion herein called spherical inclusion unknown or SIX. SIX was observed in all digestive cells and some basophilic cells of B. heckerae examined with TEM. It is a large (2-10-mu m diameter) and abundant (7 +/- 1.5 inclusions per epithelial cell section) inclusion, with a double external membrane and stacked internal lamellae. No microbial DNA was detected in digestive tubules of B. heckerae using molecular probes, preferential DNA amplification techniques, or DAPI staining, suggesting that SIX is not a unicellular parasite or symbiont. The ubiquity and abundance of SIX within cells of the digestive diverticula suggest that it has an important cellular function (positive or negative), yet to be determined

High-Throughput Measurement of Ionic Conductivity in Composition-Spread Thin Films

This paper demonstrates the feasibility of high-throughput investigation of ionic conductivity in oxygen-ion conductors. Yttria stabilized zirconia (YSZ) composition-spread thin films with nanometer-size grains were prepared by 90° off-axis reactive RF cosputtering. We compare results for two electrode configurations, namely, out-of-plane (parallel plate) and in-plane (planar interdigitated electrode) and find that the contribution from the intragrain conductivity in YSZ thin films (150 nm) is more explicit in the latter configuration because it greatly diminishes electrode effects. The intragrain oxygen ion conductivity of thin film YSZ was systematically measured as a function of yttria concentration over the range 2 mol % to 12 mol %. The results show that the measured conductivity of the YSZ thin films is close to that of corresponding bulk materials with a peak value around 3 × 10⁻⁴ S cm⁻¹ at 440 °C at the optimum Y₂O₃ concentration of 8 mol %. Validation of this technique means that it can be applied to novel chemical systems for which systematic bulk measurements have not been attempted

High-Throughput Measurement of Ionic Conductivity in Composition-Spread Thin Films

This paper demonstrates the feasibility of high-throughput investigation of ionic conductivity in oxygen-ion conductors. Yttria stabilized zirconia (YSZ) composition-spread thin films with nanometer-size grains were prepared by 90° off-axis reactive RF cosputtering. We compare results for two electrode configurations, namely, out-of-plane (parallel plate) and in-plane (planar interdigitated electrode) and find that the contribution from the intragrain conductivity in YSZ thin films (150 nm) is more explicit in the latter configuration because it greatly diminishes electrode effects. The intragrain oxygen ion conductivity of thin film YSZ was systematically measured as a function of yttria concentration over the range 2 mol % to 12 mol %. The results show that the measured conductivity of the YSZ thin films is close to that of corresponding bulk materials with a peak value around 3 × 10⁻⁴ S cm⁻¹ at 440 °C at the optimum Y₂O₃ concentration of 8 mol %. Validation of this technique means that it can be applied to novel chemical systems for which systematic bulk measurements have not been attempted

Library Design in Combinatorial Chemistry by Monte Carlo Methods

Strategies for searching the space of variables in combinatorial chemistry experiments are presented, and a random energy model of combinatorial chemistry experiments is introduced. The search strategies, derived by analogy with the computer modeling technique of Monte Carlo, effectively search the variable space even in combinatorial chemistry experiments of modest size. Efficient implementations of the library design and redesign strategies are feasible with current experimental capabilities.Comment: 5 pages, 3 figure