Partitioning of oxygen during core formation on the Earth and Mars

Core formation on the Earth and Mars involved the physical separation of metal and silicate, most probably in deep magma oceans. Although core-formation models explain many aspects of mantle geochemistry, they have not accounted for the large differences observed between the compositions of the mantles of the Earth (approximately 8 wt% FeO) and Mars (approximately 18 wt% FeO) or the smaller mass fraction of the martian core. Here we explain these differences as a consequence of the solubility of oxygen in liquid iron-alloy increasing with increasing temperature. We assume that the Earth and Mars both accreted from oxidized chondritic material. In a terrestrial magma ocean, 1,200-2,000 km deep, high temperatures resulted in the extraction of FeO from the silicate magma ocean owing to high solubility of oxygen in the metal. Lower temperatures of a martian magma ocean resulted in little or no extraction of FeO from the mantle, which thus remains FeO-rich. The FeO extracted from the Earth's magma ocean may have contributed to chemical heterogeneities in the lowermost mantle, a FeO-rich D" layer and the light element budget of the core.     

爱因斯坦A-Z

本书是一本传记性著作，记述了20世纪最伟大的科学家之一爱因斯坦的生平。与其他传记体文学不同的是，本书别出心裁的以字母表的顺序，以关键词的方式记录了爱因斯坦的生活、科研、理想等等。从第一个单词大大咧咧的（Absentmindeness），一直到最后一个单词犹太复国主义（Zionism）。每个单词作为一章的标题引出了一段或惊险、或平淡的故事。从本书中读者可以了解爱因斯坦在科学方面的天才想法，可以读到他作为普通人生活的一面——一个可怜的丈夫和父亲，还有他在核武器方面的影响，他创造了相对论却拒绝接受量子力学……     

Glucose does not influence the insulin-like growth factor (IGF) binding to carrier proteins (IGFBPs): Analysis of rat and human serum by western ligand blotting

The insulin-like growth factors (IGFs) circulate bound to specific proteins (termed IGFBP-1 through IGFBP-6) that modulate IGF bioactivity in tissues. The aim of this study was to analyse the effects of glucose on IGF binding to IGFBPs in rat and human serum by means of western ligand blotting. Serum samples were incubated with increasing concentrations of glucose (0 to 50 mmol/l), and EDTA (25 mmol/l) was added to inhibit protease activity. To analyse the effect of glucose on protection of IGFBPs from protease activity, serum from pregnant women (reported to be very rich in proteolytic activity against IGFBPs) was added to rat serum previously incubated with glucose. Glucose did not affect the¹²⁵I-IGF binding to rat and human serum IGFBPs. The intensity of IGFBP-3 bands decreased considerably during the incubation. This appeared to be due to endogenous protease activity, since the decrease was blocked by addition of EDTA. The incubationi of rat serum with pregnant human serum produced a marked attenuation of IGFBP-3 and disappearance of IGFBP-4 bands. In conclusion, our study shows that glucose does not influence the IGF binding to IGFBP-3 either in rat or in human serum, confirms the presence of endogenous proteolytic activity in normal non-pregnant serum, and demonstrates that glucose has no protective action against protease activity.     

Raman and FTIR spectroscopy of natural oxalates： Implications for the evidence of life on Mars

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formarion of oxalates. Oxalates are most readily detected using Raman spectroscopy. A comparative study of a suite of natural oxalates including weddellite, whewellite, moolooite,humboldtine, glushinskite, natroxalate and oxammite has been undertaken using Raman spectroscopy. The minerals are characterised by the Raman position of the CO stretching vibration which is cation sensitive. The band is observed at 1468 cm^-1 for weddellite, 1489 cm^-1 for moolooite, 1471cm^-1 for glushinskite and 1456 cm^-1 for natroxalate. Except for oxammite, the infrared and Raman spectra are mutually exclusive indicating the minerals are bidentate. Differences are also observed in the water OH stretching bands of the minerals. The significance of this work rests with the ability of Raman spectroscopy to identify oxalates which often occur as a film on a host rock. As such Raman spectroscopy has the potential to identify the existence or pre-existence of life forms on planets such as Mars.     

Substrate induced alterations in tryptophan pyrrolase activity in two mouse strains

Summary Total hepatic L-tryptophan 2,3-dioxygenase activity was studied in 2 mouse strains receiving i.p. injections of L-tryptophan. After a single injection, enzyme activity was increased in albino but not pigmented mice. After 3 injections, enzyme activity was reduced in both strains. This work was partially supported by grant No. 3726-22 from the Office of Research and Sponsored Programs, Wichita State University.