Huang C.,Johns Hopkins University |
Hinnov L.,Johns Hopkins University |
Fischer A.G.,University of Southern California |
Grippo A.,Santa Monica College |
Herbert T.,Brown University
Geology | Year: 2010
A high-resolution grayscale series of the pelagic Fucoid Marls (Piobbico core, central Italy) shows strong, pervasive lithological rhythms throughout the Aptian interval. A hierarchy of centimeter-to meter-scale cycles characterizes the rhythms; when calibrating ~1 m cycles to Earth's 405 k.y. orbital eccentricity cycle, these rhythms correspond to the periods of the eccentricity, obliquity, and precession index. Tuning to orbital eccentricity cycles provides a high-resolution time scale for the Aptian. Correlation to the Cismon core (northern Italy) extends the tuning to the Aptian-Barremian boundary. The tuning indicates a minimum duration of 13.42 m.y. for the Aptian Stage, where previous estimates range from 6.4 to 13.8 m.y. The combined Aptian-Albian astronomical tuning of the entire 77-m-long Piobbico core (and part of the Cismon core) provides a 25.85-m.y.-long astronomically calibrated time scale for Earth history. © 2010 Geological Society of America.
Oufiero C.E.,Towson University |
Gartner G.E.A.,Harvard University |
Gartner G.E.A.,Santa Monica College
Journal of Evolutionary Biology | Year: 2014
The shift from egg laying to live-bearing is one of the most well-studied transitions in evolutionary biology. Few studies, however, have assessed the effect of this transition on morphological evolution. Here, we evaluated the effect of reproductive mode on the morphological evolution of 10 traits, among 108 species of phrynosomatid lizards. We assess whether the requirement for passing shelled eggs through the pelvic girdle has led to morphological constraints in oviparous species and whether long gestation times in viviparous species have led to constraints in locomotor morphology. We fit models to the data that vary both in their tempo (strength and rate of selection) and mode of evolution (Brownian or Ornstein-Uhlenbeck) and estimates of trait optima. We found that most traits are best fit by a generalized multipeak OU model, suggesting differing trait optima for viviparous vs. oviparous species. Additionally, rates (σ2) of both pelvic girdle and forelimb trait evolution varied with parity; viviparous species had higher rates. Hindlimb traits, however, exhibited no difference in σ2 between parity modes. In a functional context, our results suggest that the passage of shelled eggs constrains the morphology of the pelvic girdle, but we found no evidence of morphological constraint of the locomotor apparatus in viviparous species. Our results are consistent with recent lineage diversification analyses, leading to the conclusion that transitions to viviparity increase both lineage and morphological diversification. © 2014 European Society For Evolutionary Biology.
Newman J.,CSIRO |
Fazio V.J.,CSIRO |
Lawson B.,Santa Monica College |
Crystal Growth and Design | Year: 2010
We have created the C6 Web Tool that uses an underlying metric to compare the chemical similarity of two crystallization conditions and by extension the similarity of two crystallization screens. With over 220 crystallization screens currently available for purchase, it is difficult to know what each screen contains and when it is appropriate to use that screen. The C6 Web Tool can be found at http://c6.csiro.au and is available to the crystallization community at no charge. In addition to measuring the similarity of conditions and kits, the C6 Web Tool also provides the means to examine the conditions of a crystallization kit (or kits) in novel ways. Using the C6 Web Tool, researchers can efficiently select appropriate screens to use throughout the various stages of a crystallization project. © 2010 American Chemical Society.
Chen J.,Sichuan University |
Jiang C.,Sichuan University |
Yang X.,Sichuan University |
Feng L.,Sichuan University |
And 2 more authors.
Electrochemistry Communications | Year: 2011
Carbon-supported platinum (Pt/C) catalysts were prepared via reduction in three different routes: Sodium borohydride (NaBH4), ethylene glycol (EG), and EG with NaBH4 (EG-NaBH4). The reduction conditions of each procedure were systematically optimized to achieve maximum Pt/C catalytic activity for methanol electro-oxidation as determined via cyclic voltammetry (CV). The EG-NaBH4 process showed greater activity for methanol oxidation than those prepared by the NaBH4 and EG processes and the Johnson Matthey 40 wt.% Pt/C catalyst with the support of carbon black (Pt-JM). The average size of the particles for each of the three preparation processes determined from the XRD data was 4.8, 4.1, and 2.5 nm, respectively. The average surface area of the catalyst particles was determined to be 58, 68, and 112 m2•gPt -1, respectively. Analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM), and CV suggest that the greater activity for methanol oxidation of the Pt/C catalyst prepared by the EG-NaBH4 process is due to the smaller particle size, better cluster dispersion, and an increase in the number of Pt(110) surface sites achieved using this method. © 2011 Elsevier B.V. All rights reserved.
Pepper E.D.,Santa Monica College |
Farrell M.J.,Genentext LLC |
Nord G.,Wyckoff Heights Medical Center |
Finkel S.E.,University of Southern California
Applied and Environmental Microbiology | Year: 2010
Glycation, or nonenzymatic glycosylation, is a chemical reaction between reactive carbonyl-containing compounds and biomolecules containing free amino groups. Carbonyl-containing compounds include reducing sugars such as glucose or fructose, carbohydrate-derived compounds such as methylglyoxal and glyoxal, and nonsugars such as polyunsaturated fatty acids. The latter group includes molecules such as proteins, DNA, and amino lipids. Glycation-induced damage to these biomolecules has been shown to be a contributing factor in human disorders such as Alzheimer's disease, atherosclerosis, and cataracts and in diabetic complications. Glycation also affects Escherichia coli under standard laboratory conditions, leading to a decline in bacterial population density and long-term survival. Here we have shown that as E. coli aged in batch culture, the amount of carboxymethyl lysine, an advanced glycation end product, accumulated over time and that this accumulation was affected by the addition of glucose to the culture medium. The addition of excess glucose or methylglyoxal to the culture medium resulted in a dose-dependent loss of cell viability. We have also demonstrated that glyoxylase enzyme GloA plays a role in cell survival during glycation stress. In addition, we have provided evidence that carnosine, folic acid, and aminoguanidine inhibit glycation in prokaryotes. These agents may also prove to be beneficial to eukaryotes since the chemical processes of glycation are similar in these two domains of life. © 2010, American Society for Microbiology.