Magnetic and thermal properties of amorphous Al-Gd-TM (TM=Fe,Cu) alloys

Amorphous aluminium-transition metal-rare earth alloys (Al-RE-TM) with compositions Al₆₅Gd₁₅Cu₂₀ and Al₁ Gd₁ Fe₁ have been prepared by melt spinning. X-ray diffraction studies show the average interatomic spacing in these alloys to be about 7% greater than in fcc aluminium and about 20% greater than in amorphous Al-TM-Si alloys. Thermal analysis measurements of the Al₆₅Gd₁₅Cu₂₀ and Al₁ Gd₁ Fe₁ alloys show the crystallization temperatures to be 647 and 945 K, respectively. Magnetization studies show Al₆₅Gd₁₅Cu₂₀ to be paramagnetic with a localized gadolinium moment of 8.0 ± 0.2 _B. Al₁ Gd₁ Fe₁ shows ferromagnetic behaviour, with T _c=275 K and a saturation magnetization of 124 e.m.u. g^–1. A room-temperature ⁵⁷Fe Mössbauer spectrum of Al₁ Gd₁ Fe₁ shows a well-defined quadrupole doublet with a mean splitting of about 0.4 mm s^–1. At 77 K, the Mössbauer spectrum shows a well-resolved sextet, corresponding to a mean iron hyperfine field of 96 kOe.     

Urea adducts of mono- and diesters of fatty acids

Summary The experimental work has shown how molecular configurations of fatty acid glycerides affect urea complex formation. Extraction data indicate that urea will form a complex with glycerol monopalmitate, monostearate, and mono-oleate but not under these conditions with glycerol monolinoleate or monolinolenate from mixtures containing these monoesters. Data also indicate that it is easier for urea to form a complex with monoglycerides than with diglycerides. In a mixture containing mono- and diglycerides of saturated and unsaturated fatty acids, urea will separate first on the basis of saturation, then secondly on the basis of the degree of esterification of the glycerol. An erratum to this article is available at .     

Approximating power for significance tests with one degree of freedom.

Shortcut approximate equations are described that provide estimates of the sample size required for 50% power (α?=?0.05, two-tailed) for 1 degree of freedom tests of significance for simple correlations, differences between 2 independent group means, and Pearson's chi-square test for 2?×?2 contingency tables. These sample sizes should be thought of as minima, because power equal to 50% means that the chance of a significant finding is that of flipping a fair coin. A more desirable sample size can be computed by simply doubling the 50% sample sizes, which is shown to result in power between 80% and 90%. With these simple tools, power can be estimated rapidly, which, it is hoped, will lead to greater use and understanding of power in the teaching of statistics and in research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loss of hippocampal CA1 pyramidal neurons correlates with memory impairment in rats with ischemic or neurotoxin lesions.

Rats were trained for 20 days in a modified T maze to perform an invariant, tactile discrimination and a variable, delayed spatial discrimination, and then were exposed either to 30 min of transient forebrain ischemia or to low- or high-dose ibotenic acid to damage the dorsal hippocampus bilaterally. Only rats exposed to ischemia or high-dose ibotenic acid demonstrated impaired performance during 30 postoperative test days on both aspects of the task (p?p?     

Thermal expansion of Bi2.2Sr1.8CaCu2Ox superconductor single crystals

Using a low-temperature stage X-ray diffractometer, we have investigated the temperature dependence of the lattice parameters of single crystal superconductors Bi₂Sr_1.8CaCu₂O_x. The experimental results show that (i) the lattice constants increase linearly with increasing temperature above about 100 K; (ii) thec-axis lattice parameter shows a kink in the superconducting transition region, while thea, b-axis parameters do not show any anomalous behavior in this region; (iii) botha, b, andc show negative thermal expansion coefficients below 40–50 K, which may be related to the characteristics of the Cu-O bond.     

How temperature changes reset a circadian oscillator

Circadian rhythms control many physiological activities. The environmental entrainment of rhythms involves the immediate responses of clock components. Levels of the clock protein FRQ were measured in Neurospora at various temperatures; at higher temperatures, the amount of FRQ oscillated around higher levels. Absolute FRQ amounts thus identified different times at different temperatures, so temperature shifts corresponded to shifts in clock time without immediate synthesis or turnover of components. Moderate temperature changes could dominate light-to-dark shifts in the influence of circadian timing. Temperature regulation of clock components could explain temperature resetting of rhythms and how single transitions can initiate rhythmicity from characteristic circadian phases.