Molecular and Paleontological Evidence for a Post-Cretaceous Origin of Rodents

The timing of the origin and diversification of rodents remains controversial, due to conflicting results from molecular clocks and paleontological data. The fossil record tends to support an early Cenozoic origin of crown-group rodents. In contrast, most molecular studies place the origin and initial diversification of crown-Rodentia deep in the Cretaceous, although some molecular analyses have recovered estimated divergence times that are more compatible with the fossil record. Here we attempt to resolve this conflict by carrying out a molecular clock investigation based on a nine-gene sequence dataset and a novel set of seven fossil constraints, including two new rodent records (the earliest known representatives of Cardiocraniinae and Dipodinae). Our results indicate that rodents originated around 61.7–62.4 Ma, shortly after the Cretaceous/Paleogene (K/Pg) boundary, and diversified at the intraordinal level around 57.7–58.9 Ma. These estimates are broadly consistent with the paleontological record, but challenge previous molecular studies that place the origin and early diversification of rodents in the Cretaceous. This study demonstrates that, with reliable fossil constraints, the incompatibility between paleontological and molecular estimates of rodent divergence times can be eliminated using currently available tools and genetic markers. Similar conflicts between molecular and paleontological evidence bedevil attempts to establish the origination times of other placental groups. The example of the present study suggests that more reliable fossil calibration points may represent the key to resolving these controversies.Organismic and Evolutionary Biolog

Genome-wide structural variant analysis identifies risk loci for non-Alzheimer’s dementias

We characterized the role of structural variants, a largely unexplored type of genetic variation, in two non-Alzheimer’s dementias, namely Lewy body dementia (LBD) and frontotemporal dementia (FTD)/amyotrophic lateral sclerosis (ALS). To do this, we applied an advanced structural variant calling pipeline (GATK-SV) to short-read whole-genome sequence data from 5,213 European-ancestry cases and 4,132 controls. We discovered, replicated, and validated a deletion in TPCN1 as a novel risk locus for LBD and detected the known structural variants at the C9orf72 and MAPT loci as associated with FTD/ALS. We also identified rare pathogenic structural variants in both LBD and FTD/ALS. Finally, we assembled a catalog of structural variants that can be mined for new insights into the pathogenesis of these understudied forms of dementia

pH-Insensitive Bimetallic Catalyst for the Abatement of Dye Pollutants by Photo-Fenton Oxidation

A bimetallic (copper and iron) catalyst supported on MCM-41 has been synthesized by chemical vapor deposition and evaluated for the degradation of Orange II by the photo-Fenton process. An in situ oxidation method we recently developed was applied to stabilize the metals supported on MCM-41, achieving an extremely low metal leaching level during the photo-Fenton process (<0.7 mg/L for the total metals, <0.35 mg/L for each individual metal). This new bimetallic catalyst can function well over a wide pH range because iron works best at pH 3 as a Fenton catalyst while copper plays the leading role as a Fenton-like catalyst at higher pH. Experimental results show that using FeCu/MCM-41, 93%, 83%, and 78% of total organic carbon (TOC) removals can be achieved for the photo-Fenton degradation of Orange H at pH 3, 5.5, and 7, respectively. This Fe Cu/MCM-41 catalyst maintains its high catalytic activity after 10 consecutive runs, as a result of its extremely low metal leaching and strong chemical bonding of metal-O-Si. The experimental data have been fitted with a proposed kinetics model. It was shown that the activation energy of the oxidation reaction using a bimetallic catalyst is lower than that using a conventional monometallic catalyst. This is a significant improvement for the Fenton reaction system

In situ oxidation for stabilization of Fe/MCM-41 catalyst prepared by metal organic chemical vapor deposition

Oxygen has been found to be a key factor in the process of metal organic chemical vapour deposition (MOCVD) to stabilize the iron catalyst supported on MCM-41, particularly in the acidic aqueous reaction. Such stabilization is achieved by in situ oxidation of iron, which intercalates oxygen atoms into the framework of both siliceous and ferric oxides by developing Fe-O-Si and Fe-O-Fe bonds, respectively. This stable Fe/MCM-41 catalyst shows an excellent mineralization efficiency of orange 11 of similar to 85\% and an extremely low iron leaching concentration of similar to 0.17 mg/L. The catalyst maintains its excellent catalytic activity after multiple reaction runs under acidic aqueous medium. (c) 2007 Elsevier B.V. All rights reserved

A high performance bimetallic catalyst for photo-Fenton oxidation of Orange II over a wide pH range

A bimetallic catalyst supported on MCM-41 was synthesized by chemical vapour deposition and evaluated in the photo-Fenton degradation of Orange II. An in situ oxidation method recently developed in our group was applied to stabilize the metal catalyst supported on MCM-41, achieving an extremely low metal leaching level. This FeCu/MCM-41 shows TOC removals of 93\%, 83\%, and 78\% at pHs of 3, 5.5, and 7, respectively, and maintains its high catalytic activity after 10 consecutive runs. This catalyst successfully overcomes the two problems faced by the heterogeneous photo-Fenton process - metal leaching and narrow working pH range. (C) 2007 Elsevier B.V. All rights reserved