Tethered Ru(II) catalysts containing a Ru–I bond

Two new iodide-containing derivatives of the widely-adopted arene/Ru(II)/TsDPEN catalysts have been prepared and fully characterised, including through X-ray crystallography. They have been evaluated as catalysts for the asymmetric reduction of acetophenone under both transfer (ATH) and pressure hydrogenation (AH) conditions. The iodide-containing complexes are equally efficient in the ATH reaction, but less active in the AH reaction compared to the chloride derivatives

Non-orthogonal configuration interaction with single substitutions for core-excited states: An extension to doublet radicals

In this paper, we present an open-shell extension of the non-orthogonal configuration interaction singles (NOCIS) method for the calculation of core-excited states, intended for peak assignment in XAS spectra of doublet radicals. This extension requires the consideration of additional configurations due to the singly occupied open-shell orbital, and the addition of essential orbital relaxation effects is found to provide a significant improvement on standard CIS, while maintaining the desirable properties of spin purity, variationality, and size consistency. We apply this method to the calculation of core excitations for several open-shell molecules and demonstrate that it performs competitively with other available methods, despite a lack of dynamic correlation. In particular, relative to CVS-ADC(2)-x, RMS error is reduced by a factor of 6 over usual orthogonal CIS and is comparable to time-dependent density functional theory with the best short-range corrected functionals

Lunar basalt chronology, mantle differentiation and implications for determining the age of the Moon

Despite more than 40 years of studying Apollo samples, the age and early evolution of the Moon remain contentious. Following the formation of the Moon in the aftermath of a giant impact, the resulting Lunar Magma Ocean (LMO) is predicted to have generated major geochemically distinct silicate reservoirs, including the sources of lunar basalts. Samples of these basalts, therefore, provide a unique opportunity to characterize these reservoirs. However, the precise timing and extent of geochemical fractionation is poorly constrained, not least due to the difficulty in determining accurate ages and initial Pb isotopic compositions of lunar basalts. Application of an in situ ion microprobe approach to Pb isotope analysis has allowed us to obtain precise crystallization ages from six lunar basalts, typically with an uncertainty of about ±10Ma, as well as constrain their initial Pb-isotopic compositions. This has enabled construction of a two-stage model for the Pb-isotopic evolution of lunar silicate reservoirs, which necessitates the prolonged existence of high-μ reservoirs in order to explain the very radiogenic compositions of the samples. Further, once firm constraints on U and Pb partitioning behaviour are established, this model has the potential to help distinguish between conflicting estimates for the age of the Moon. Nonetheless, we are able to constrain the timing of a lunar mantle reservoir differentiation event at 4376±18Ma, which is consistent with that derived from the Sm–Nd and Lu–Hf isotopic systems, and is interpreted as an average estimate of the time at which the high-μ urKREEP reservoir was established and the Ferroan Anorthosite (FAN) suite was formed

Workers on the Run: Recession and the Pressure on Workplace Rights - The 34th Annual Kenneth M. Piper Lecture

This lecture discusses the impact of the recent recession, both directly and indirectly, on the rights of workers in the U.S. and internationally. Employers are increasingly relying on temporary/contingent workers, and even unpaid interns who have few jobs protections and no benefits. This practice negatively impacts the wages and bargaining power of the core labor force as well as overall job creation. Particularly pronounced is the misclassification of jobs and failure to pay minimum wage and/or overtime benefits contrary to contractual requirements. There is evidence that the recession has made it politically acceptable to re-write existing employment agreements, with federal and local governments seeking to reduce payouts to municipal workers, auto workers and others. Martin J. Mulloy and Gwynne A. Wilcox, two labor and employment leaders, provide commentary on the lecture

PtrA is required for coordinate regulation of gene expression during phosphate stress in a marine Synechococcus

Previous microarray analyses have shown a key role for the two-component system PhoBR (SYNW0947, SYNW0948) in the regulation of P transport and metabolism in the marine cyanobacterium Synechococcus sp. WH8102. However, there is some evidence that another regulator, SYNW1019 (PtrA), probably under the control of PhoBR, is involved in the response to P depletion. PtrA is a member of the cAMP receptor protein transcriptional regulator family that shows homology to NtcA, the global nitrogen regulator in cyanobacteria. To define the role of this regulator, we constructed a mutant by insertional inactivation and compared the physiology of wild-type Synechcococcus sp. WH8102 with the ptrA mutant under P-replete and P-stress conditions. In response to P stress the ptrA mutant failed to upregulate phosphatase activity. Microarrays and quantitative RT-PCR indicate that a subset of the Pho regulon is controlled by PtrA, including two phosphatases, a predicted phytase and a gene of unknown function psip1 (SYNW0165), all of which are highly upregulated during P limitation. Electrophoretic mobility shift assays indicate binding of overexpressed PtrA to promoter sequences upstream of the induced genes. This work suggests a two-tiered response to P depletion in this strain, the first being PhoB-dependent induction of high-affinity PO4 transporters, and the second the PtrA-dependent induction of phosphatases for scavenging organic P. The levels of numerous other transcripts are also directly or indirectly influenced by PtrA, including those involved in cell-surface modification, metal uptake, photosynthesis, stress responses and other metabolic processes, which may indicate a wider role for PtrA in cellular regulation in marine picocyanobacteria

Workers on the Run: Recession and the Pressure on Workplace Rights - The 34th Annual Kenneth M. Piper Lecture

This lecture discusses the impact of the recent recession, both directly and indirectly, on the rights of workers in the U.S. and internationally. Employers are increasingly relying on temporary/contingent workers, and even unpaid interns who have few jobs protections and no benefits. This practice negatively impacts the wages and bargaining power of the core labor force as well as overall job creation. Particularly pronounced is the misclassification of jobs and failure to pay minimum wage and/or overtime benefits contrary to contractual requirements. There is evidence that the recession has made it politically acceptable to re-write existing employment agreements, with federal and local governments seeking to reduce payouts to municipal workers, auto workers and others. Martin J. Mulloy and Gwynne A. Wilcox, two labor and employment leaders, provide commentary on the lecture

Direct formation of tethered Ru(II) catalysts using arene exchange

An ‘arene exchange’ approach has been successfully applied for the first time to the synthesis of Ru(II)-based ‘tethered’ reduction catalysts directly from their ligands in one step. This provides an alternative method for the formation of known complexes, and a route to a series of novel complexes. The novel complexes are highly active in both asymmetric transfer and pressure hydrogenation of ketones