Superconductivity in the Nb-Ru-Ge σ\sigma-Phase

We show that the previously unreported ternary $\sigma$-phase material Nb$_{20.4}$Ru$_{5.7}$Ge$_{3.9}$ is a superconductor with a critical temperature of 2.2 K. Temperature-dependent magnetic susceptibility, resistance, and specific heat measurements were used to characterize the superconducting transition. The Sommerfeld constant $\gamma$ for Nb$_{20.4}$Ru$_{5.7}$Ge$_{3.9}$ is 91 mJ mol-f.u.$^{-1}$K$^{-2}$ and the specific heat anomaly at the superconducting transition, $\Delta$C/$\gamma$T$_c$, is approximately 1.38. The zero-temperature upper critical field ($\mu_0$H$_{c2}$(0)) was estimated to be 2 T by resistance data. Field-dependent magnetization data analysis estimated $\mu_0$H$_{c1}$(0) to be 5.5 mT. Thus, the characterization shows Nb$_{20.4}$Ru$_{5.7}$Ge$_{3.9}$ to be a type II BCS superconductor. This material appears to be the first reported ternary phase in the Nb-Ru-Ge system, and the fact that there are no previously reported binary Nb-Ru, Nb-Ge, or Ru-Ge $\sigma$-phases shows that all three elements are necessary to stabilize the material. A $\sigma$-phase in the Ta-Ru-Ge system was synthesized but did not display superconductivity above 1.7 K, which suggests that electron count cannot govern the superconductivity observed. Preliminary characterization of a possible superconducting $\sigma$-phase in the Nb-Ru-Ga system is also reported.Comment: 7 pages, 8 figures, 3 table

Saturation bounds for smooth varieties

We prove bounds on the saturation degrees of homogeneous ideals (and their powers) defining smooth complex projective varieties. For example, we show that a classical statement due to Macualay for zero-dimensional complete intersection ideals holds for any smooth variety. For curves, we bound the saturation degree of powers in terms of the regularity

Anesthetic Activity of Acetylated MS-222 in Tilapia (Oreochromis Niloticus)

A group of 8 tilapia (Oreochromis niloticus) were anesthetized once per week for six consecutive weeks, using tricaine methanesulfonate (MS-222) in the water. Time for the fish to reach anesthesia decreased significantly over the first four weeks, and then plateaued at about 27% below the first anesthetic exposure. These results suggest induction of the liver enzymes that convert MS-222 into metabolites, one or more of which have higher anesthetic activity than the parent compound. Major metabolites of MS-222 have been identified as part of regulatory studies evaluating residue persistence in food fishes. One of these metabolites, N-acetyl-3-aminobenzoic acid ethyl ester, which is acetylated MS-222, was selected for testing of anesthetic activity in tilapia. This report shows results of the testing, and speculates as to the potential utility of the acetylated metabolite of MS-222 as an alternate anesthetic agent in fish

Eye movements of students with learning disabilities in reading: A study of problem-solving strategies

In this exploratory study, eye movements of students with and without a learning disability in reading were recorded as they solved a set of third grade science problems. The recorded eye-gaze information included location of eye-gaze fixation on a computer screen, duration of fixation, the path of eye movement, and duration between fixations. The results revealed statistically significant differences in latent response time, question-zone fixation time, total fixations and correct responses