Imposing high-symmetry and tuneable geometry on lanthanide centres with chelating Pt and Pd metalloligands

Exploitation of HSAB preferences allows for high-yield, one-pot syntheses of lanthanide complexes chelated by two Pd or Pt metalloligands, [MII(SAc)4]2− (SAc− = thioacetate, M = Pd, Pt). The resulting complexes with 8 oxygen donors surrounding the lanthanides can be isolated in crystallographically tetragonal environments as either [NEt4]+ (space group: P4/mcc) or [PPh4]+ (space group: P4/n) salts. In the case of M = Pt, the complete series of lanthanide complexes has been structurally characterized as the [NEt4]+ salts (except for Ln = Pm), while the [PPh4]+ salts have been structurally characterized for Ln = Gd–Er, Y. For M = Pd, selected lanthanide complexes have been structurally characterized as both salts. The only significant structural difference between salts of the two counter ions is the resulting twist angle connecting tetragonal prismatic and tetragonal anti-prismatic configurations, with the [PPh4]+ salts approaching ideal D4d symmetry very closely (φ = 44.52–44.61°) while the [NEt4]+ salts exhibit intermediate twist angles in the interval φ = 17.28–27.41°, the twist increasing as the complete 4f series is traversed. Static magnetic properties for the latter half of the lanthanide series are found to agree well in the high temperature limit with the expected Curie behavior. Perpendicular and parallel mode EPR spectroscopy on randomly oriented powder samples and single crystals of the Gd complexes with respectively Pd- and Pt-based metalloligands demonstrate the nature of the platinum metal to strongly affect the spectra. Consistent parametrization of all of the EPR spectra reveals the main difference to stem from a large difference in the magnitude of the leading axial term, B02, this being almost four times larger for the Pt-based complexes as compared to the Pd analogues, indicating a direct Pt(5dz2)–Ln interaction and an arguable coordination number of 10 rather than 8. The parametrization of the EPR spectra also confirms that off-diagonal operators are associated with non-zero parameters for the [NEt4]+ salts, while only contributing minimally for the [PPh4]+ salts in which lanthanide coordination approximates D4d point group symmetry closely.LHD acknowledges support from NSF-CCT EMT 08-517. (08-517 - NSF-CCT EMT

WorldMap – A Geospatial Framework for Collaborative Research

WorldMap is a web-based, map-centric data exploration system built on open-source geospatial technology at Harvard University. It is designed to serve collaborative research and teaching, but is also accessible to the general public. This article explains WorldMap's basic functions through several historical research projects, demonstrating its flexible scale (from neighborhood to continent) and diverse research themes (social, political, economic, cultural, infrastructural, etc.). Also shared in this article are our experiences in handling technical and institutional challenges during system development, such as synchronization of software components being developed by multiple organizations; juggling competing priorities for serving individual requests and developing a system that will enable users to support themselves; balancing promotion of the system usage with constraints on infrastructure investment; harnessing volunteered geographic information while managing data quality; as well as protecting copyrights, preserving permanent links and citations, and providing long-term archiving.East Asian Languages and Civilization

Harmonic generation in ring-shaped molecules

We study numerically the interaction between an intense circularly polarized laser field and an electron moving in a potential which has a discrete cylindrical symmetry with respect to the laser pulse propagation direction. This setup serves as a simple model, e.g., for benzene and other aromatic compounds. From general symmetry considerations, within a Floquet approach, selection rules for the harmonic generation [O. Alon Phys. Rev. Lett. 80 3743 (1998)] have been derived recently. Instead, the results we present in this paper have been obtained solving the time-dependent Schroedinger equation ab initio for realistic pulse shapes. We find a rich structure which is not always dominated by the laser harmonics.Comment: 15 pages including 7 figure

Partition of Environmental Chemicals between Maternal and Fetal Blood and Tissues

Passage of environmental chemicals across the placenta has important toxicological consequences, as well as for choosing samples for analysis and for interpreting the results. To obtain systematic data, we collected in 2000 maternal and cord blood, cord tissue, placenta, and milk in connection with births in the Faroe Islands, where exposures to marine contaminants is increased. In 15 sample sets, we measured a total of 87 environmental chemicals, almost all of which were detected both in maternal and fetal tissues. The maternal serum lipid-based concentrations of organohalogen compounds averaged 1.7 times those of cord serum, 2.8 times those of cord tissue and placenta, and 0.7 those of milk. For organohalogen compounds detectable in all matrices, a high degree of correlation between concentrations in maternal serum and the other tissues investigated was generally observed (r2 > 0.5). Greater degree of chlorination resulted in lower transfer from maternal serum into milk. Concentrations of pentachlorbenzene, γ-hexachlorocyclohexane, and several polychlorinated biphenyl congeners with low chlorination were higher in fetal samples and showed poor correlation with maternal levels. Perfluorinated compounds occurred in lower concentrations in cord serum than in maternal serum. Cadmium, lead, mercury, and selenium were all detected in fetal samples, but only mercury showed close correlations among concentrations in different matrices. Although the environmental chemicals examined pass through the placenta and are excreted into milk, partitions between maternal and fetal samples are not uniform

Electronic Structure of Transition-Metal Dicyanamides Me[N(CN)2_2]2_2 (Me = Mn, Fe, Co, Ni, Cu)

The electronic structure of Me[N(CN)$_2$]$_2$ (Me=Mn, Fe, Co, Ni, Cu) molecular magnets has been investigated using x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) as well as theoretical density-functional-based methods. Both theory and experiments show that the top of the valence band is dominated by Me 3d bands, while a strong hybridization between C 2p and N 2p states determines the valence band electronic structure away from the top. The 2p contributions from non-equivalent nitrogen sites have been identified using resonant inelastic x-ray scattering spectroscopy with the excitation energy tuned near the N 1s threshold. The binding energy of the Me 3d bands and the hybridization between N 2p and Me 3d states both increase in going across the row from Me = Mn to Me = Cu. Localization of the Cu 3d states also leads to weak screening of Cu 2p and 3s states, which accounts for shifts in the core 2p and 3s spectra of the transition metal atoms. Calculations indicate that the ground-state magnetic ordering, which varies across the series is largely dependent on the occupation of the metal 3d shell and that structural differences in the superexchange pathways for different compounds play a secondary role.Comment: 20 pages, 11 figures, 2 table

Sperm Aneuploidy in Faroese Men with Lifetime Exposure to Dichlorodiphenyldichloroethylene (DDE) and Polychlorinated Biphenyl (PCB) Pollutants.

Background: Although it is known that sperm aneuploidy contributes to early pregnancy losses and congenital abnormalities, the causes are unknown and environmental contaminants are suspected. Objectives: Our goal was to evaluate associations between lifetime exposure to organochlorines, specifically dichlorodiphenyldicholorethylene (p,p´-DDE) and polychlorinated biphenyls (PCBs), and sperm aneuploidy in men from the general population of the Faroe Islands, a population with a known history of organochlorine exposures. Methods: Serum and semen samples from men (n = 90) 22–44 years old who participated in Faroe Islands health studies were analyzed for p,p´-DDE and PCBs 118, 138, 153, and 180 and adjusted for total lipids. Cord blood and age-14 serum were available for a subgroup (n = 40) and were also analyzed for p,p´-DDE and PCBs. Sperm fluorescence in situhybridization (FISH) for chromosomes X, Y, and 18 was used to determine rates of XX18, XY18, YY18, and total disomy. Multivariable adjusted Poisson models were used to estimate the relationship between organochlorine exposure and sperm disomy outcomes. Results: Adult p,p´-DDE and total PCB serum concentrations were both associated with significantly increased rates of XX18, XY18, and total disomy. Age-14 p,p´-DDE and PCB concentrations were both associated with significantly increased rates of XX, XY, and total disomy in adulthood. Associations between cord blood concentrations of p,p´-DDE and PCBs and sperm disomy in adulthood were not consistently significant. Conclusions: Organochlorine exposures measured at age 14 and in adulthood were associated with sperm disomy in this sample of high-exposure men, suggesting that the impacts of persistent pollutants on testicular maturation and function require further investigation

Private Financing or Not, That is the Question: Lessons from the Light Rail Systems in Spain

The objective of this paper is to analyze if there is any difference between the light rail systems in Spain according to whether they have been carried out through public financing or private financing (totally or partially). The importance of this study lies in the fact that, for decades, the public–private partnership has been proposed as an alternative to public financing of public transport projects in order to obtain additional financial resources, reduce the public deficit, and increase efficiency. However, there are hardly any detailed studies describing how these initiatives have turned out. Therefore, the present study analyzes if there is any difference in the main variables explaining the performance of light rail projects in Spain depending on their source of funding can be found. For this, the relationship between variables related to design, operation and costs of the projects, and the percentage of private financing were statistically analyzed. As the most relevant conclusion, we underline the fact that the investment per passenger increases when financing is completely private. This would indicate that the most cost-effective lines, from a social standpoint, were financed totally or partially by the public administrations, whereas the least beneficial ones for society were assigned to private enterprises. This finding provides an advance in the knowledge of the consequences of private participation in the financing of public transport projects, indicating, moreover, that the biggest beneficiaries of this type of projects might be the construction companies and the politicians involvedThe authors would like to thank the ERDF of European Union for financial support via project ‘‘Herramienta para la evaluacio´n previa de infraestructuras de transporte pu´blico’’ (GGI3003IDIE). We also thank to Public Works Agency and Regional Ministry of Public Works and Housing of the Regional Government of Andalusia (AOPJA) and the Ministry of Education, Culture and Sports of the Government of Spain

On the possibility of magneto-structural correlations: detailed studies of di-nickel carboxylate complexes

A series of water-bridged dinickel complexes of the general formula [Ni<sub>2</sub>(μ<sub>2</sub>-OH<sub>2</sub>)(μ2- O<sub>2</sub>C<sup>t</sup>Bu)<sub>2</sub>(O<sub>2</sub>C<sup>t</sup>Bu)2(L)(L0)] (L = HO<sub>2</sub>C<sup>t</sup>Bu, L0 = HO<sub>2</sub>C<sup>t</sup>Bu (1), pyridine (2), 3-methylpyridine (4); L = L0 = pyridine (3), 3-methylpyridine (5)) has been synthesized and structurally characterized by X-ray crystallography. The magnetic properties have been probed by magnetometry and EPR spectroscopy, and detailed measurements show that the axial zero-field splitting, D, of the nickel(ii) ions is on the same order as the isotropic exchange interaction, J, between the nickel sites. The isotropic exchange interaction can be related to the angle between the nickel centers and the bridging water molecule, while the magnitude of D can be related to the coordination sphere at the nickel sites

UNC2025, a MERTK Small-Molecule Inhibitor, Is Therapeutically Effective Alone and in Combination with Methotrexate in Leukemia Models

MERTK tyrosine kinase is ectopically expressed in 30–50% of acute lymphoblastic leukemias (ALL) and over 80% of acute myeloid leukemias (AML) and is a potential therapeutic target. Here, we evaluated the utility of UNC2025, a MERTK tyrosine kinase inhibitor, for treatment of acute leukemia