Mixed Network Former Effect in Ion-Conducting Alkali Borophosphate Glasses: Structure/Property Correlations in the System [M2O]1/3[(B2O3)x(P2O5)1–x]2/3 (M = Li, K, Cs)

Glasses in the system [M2O]1/3[(B2O3)x(P2O5)1–x]2/3(M = Li, K, Cs) (0.0 ≤ x ≤ 1.0) were prepared by standard melt-quenching procedures, and their physical properties were characterized by thermal analysis, density measurements, and impedance spectroscopy. Their atomic level structures were comprehensively characterized by Raman spectroscopy, by X-ray photoelectron spectroscopy (XPS), and by 11B, 31P, and 7Li as well as 133Cs high resolution solid state magic-angle-spinning (MAS) NMR techniques. 31P MAS NMR peak assignments were aided by the presence or absence of homonuclear indirect 31P–31P spin–spin interactions, “J-coupling”, as detected via refocused INADEQUATE techniques. Consistent speciations of the phosphate and borate network former components in terms of the various PnmB and BnmPunits, where n is the number of bridging oxygens (BOs) and m is the number of B or P units bonded to P or B, respectively, present in these glasses were derived from 11B MAS NMR, combined with both 31P MAS NMR and XPS line shape analyses, constrained by charge and mass balance considerations. The speciation of the BO species in the glassy network was quantified both by O 1s XPS and 11B{31P} rotational echo double resonance spectroscopy. Both experiments indicate a strong preference of heteroatomic B–O–P over homoatomic P–O–P and B–O–B linkages to the extent that close to the maximum number of possible B4–O–P linkages is formed. Further, the structural speciations of the borate and phosphate species, together with bond valence (BV) analyses of the charge redistribution on the various structural units, indicate that the alkali network modifier oxide is not proportionally shared between the two network former components B and P in these systems. Rather, the amounts and types of the various borate and phosphate species are found to be consistent with the negative charge brought in by the alkali modifier M2O being distributed more toward the phosphate structural units which are suggested to attract a larger concentration of network modifier species than predicted by the bulk composition. The experimental results obtained from these studies help in understanding the strongly nonlinear compositional dependence of the glass transition temperature and the ionic conductivity in terms of detailed atomic-level structural information. The emerging structural principles appear to be general to all of the alkali borophosphate glass systems, with the type of alkali ion network modifier producing only minor variations

On Designing an Active Tail for Legged Robots: Simplifying Control via Decoupling of Control Objectives

This work explores the possible roles of active tails for steady-state legged-locomotion. A series of simple models are proposed which capture the dynamics of an idealized running system with an active tail. The models suggest that the control objectives of injecting energy into the system and stabilizing body-pitch can be effectively decoupled via proper tail design: a long, light tail. Thus the overall control problem can be simplified, using the tail exclusively to stabilize body-pitch: this effectively relaxes the constraints on the leg-actuators, allowing them to be recruited specifically for adding energy into the system. We show in simulation that models with long-light tails are better able to reject perturbations to body-pitch than short-heavy tails with the same moment of inertia. Further, we present the results of a one degree-of-freedom tail mounted on the open-loop controlled quadruped robot Cheetah-Cub. Our results show that an active tail can greatly improve both forward velocity and reduce body-pitch per stride, while adding minimal complexity. Further, the results validate the long-light tail design: shorter, heavier tails are much more sensitive to configuration and control parameter changes than longer and lighter tails with the same moment of inertia

Mixed network former effect in ion-conducting Alkali borophosphate glasses: structure/property correlations in the system '['M IND. 2'O] IND. 1/3''['('B IND. 2''O IND. 3') IND. x''('P IND. 2''O IND. 5') IND. 1-x'] IND. 2/3' (M = 'LI', K, 'CS')

Glasses in the system '['M IND. 2'O] IND. 1/3''['('B IND. 2''O IND. 3') IND. x''('P IND. 2''O IND. 5') IND. 1-x'] IND. 2/3' (M = 'LI', K, 'CS') (0.0 'MENOR OU IGUAL' x 'MENOR OU IGUAL' 1.0) were prepared by standard melt-quenching procedures, and their physical properties were characterized by thermal analysis, density measurements, and impedance spectroscopy. Their atomic level structures were comprehensively characterized by Raman spectroscopy, by X-ray photoelectron spectroscopy (XPS), and by ' ANTPOT. 11 B', 'ANTPOT. 31 P', and 'ANTPOT. 7 LI' as well as 'ANTPOT. 133 CS' high resolution solid state magic-angle-spinning (MAS) NMR techniques. 'ANTPOT. 31 P' MAS NMR peak assignments were aided by the presence or absence of homonuclear indirect 'ANTPOT. 31 P'-'ANTPOT. 31 P' spin–spin interactions, "J-coupling", as detected via refocused INADEQUATE techniques. Consistent speciations of the phosphate and borate network former components in terms of the various 'P POT. n IND. mB' and 'B POT.n IND. mP' units, where n is the number of bridging oxygens (BOs) and m is the number of B or P units bonded to P or B, respectively, present in these glasses were derived from 'ANTPOT. 11 B' MAS NMR, combined with both 'ANTPOT. 31 P' MAS NMR and XPS line shape analyses, constrained by charge and mass balance considerations. The speciation of the BO species in the glassy network was quantified both by O 1s XPS and 'ANTPOT. 11 B'{'ANTPOT. 31 P'} rotational echo double resonance spectroscopy. Both experiments indicate a strong preference of heteroatomic B-O-P over homoatomic P-O-P and B-O-B linkages to the extent that close to the maximum number of possible 'B POT. 4'-O-P linkages is formed. Further, the structural speciations of the borate and phosphate species, together with bond valence (BV) analyses of the charge redistribution on the various structural units, indicate that the alkali network modifier oxide is not proportionally shared between the two network former components B and P in these systems. Rather, the amounts and types of the various borate and phosphate species are found to be consistent with the negative charge brought in by the alkali modifier 'M IND. 2'O being distributed more toward the phosphate structural units which are suggested to attract a larger concentration of network modifier species than predicted by the bulk composition. The experimental results obtained from these studies help in understanding the strongly nonlinear compositional dependence of the glass transition temperature and the ionic conductivity in terms of detailed atomic-level structural information. The emerging structural principles appear to be general to all of the alkali borophosphate glass systems, with the type of alkali ion network modifier producing only minor variations.Deutsche Forschungsgemeinschaft (SFB 458; Ionic Motion in Disordered Materials)National Science Foundation (DMR, Materials World Network NSFDMR 0701564

NMR and conductivity studies of the mixed glass former effect in lithium borophosphate glasses

Alkali ion charge transport has been studied in a series of mixed glass former lithium borophosphate glasses of composition 0.33Li2O + 0.67[xB2O3 + (1 – x)P2O5]. The entire concentration range, 0.0 ≤ x ≤ 1.0, from pure glassy Li2P4O11 to pure glassy Li2B4O7 has been examined while keeping the molar fraction of Li2O constant. Electrical conductivity measurements and nuclear magnetic resonance techniques such as spin relaxometry, line shape analysis, and stimulated-echo spectroscopy were used to examine the temperature and frequency dependence of the Li+ ion motion over wide ranges of time scale and temperature. By accurately determining motional time scales and activation energies over the entire composition range the ion dynamics and the charge transport are found to be fastest if the borate and the phosphate fractions are similar. The nonlinear variation of the charge conduction, the most notable feature of the mixed glass former effect, is discussed in terms of the composition dependence of network former units which determine the local glass structure

New Lithium Chalcogenidotetrelates, LiChT: Synthesis and\ud Characterization of the Li+-Conducting Tetralithium ortho-\ud Sulfidostannate Li4SnS4

A new lithium chalcogenidotetrelate, denoted as LiChT phase, with the elemental combination Li/Sn/S was synthesized as solvent-free and solvent-containing salts. We present and discuss syntheses, crystal structures, spectroscopic and thermal properties of the phases, as well as the Li+ ion conductivity of Li4SnS4, which is formally related to the thio-LISICON parent system Li4GeS4, and thus represents the first member of a new thiostannate-LISICON family. The solvent-free title compound shows a very promising Li+ ion conductivity of 7 × 10–5 S·cm–1 at 20 °C and 3 × 10–3 S·cm–1 at 100 °C, which is exceptionally high for a ternary compound. Activation energies for the lithium ion transport measured via impedance spectroscopy (0.41 eV) correlate reasonably well with the values (0.29 to 0.33 eV) deduced from ionic mobility studies by 7Li solid-state NMR spectroscopy. NMR two-time correlation functions suggest the occurrence of an additional, geometrically more restricted, ultra-slow-motional process down to 121 KDeutsche Forschungsgemeinschaft (DFG)Bundesministerium für Bildung und Forschung (BMBF

Structure and Ionic Conductivity in the Mixed-Network Former Chalcogenide Glass System [Na2S]2/3[(B2S3)x(P2S5)1–x]1/3

Glasses in the system [Na2S]2/3[(B2S3)x(P2S5)1–x]1/3 (0.0 ≤ x ≤ 1.0) were prepared by the melt quenching technique, and their properties were characterized by thermal analysis and impedance spectroscopy. Their atomic-level structures were comprehensively characterized by Raman spectroscopy and 11B, 31P, and 23Na high resolution solid state magic-angle spinning (MAS) NMR techniques. 31P MAS NMR peak assignments were made by the presence or absence of homonuclear indirect 31P–31P spin–spin interactions as detected using homonuclear J-resolved and refocused INADEQUATE techniques. The extent of B–S–P connectivity in the glassy network was quantified by 31P{11B} and 11B{31P} rotational echo double resonance spectroscopy. The results clearly illustrate that the network modifier alkali sulfide, Na2S, is not proportionally shared between the two network former components, B and P. Rather, the thiophosphate (P) component tends to attract a larger concentration of network modifier species than predicted by the bulk composition, and this results in the conversion of P2S74–, pyrothiophosphate, Na/P = 2:1, units into PS43–, orthothiophosphate, Na/P = 3:1, groups. Charge balance is maintained by increasing the net degree of polymerization of the thioborate (B) units through the formation of covalent bridging sulfur (BS) units, B–S–B. Detailed inspection of the 11B MAS NMR spectra reveals that multiple thioborate units are formed, ranging from neutral BS3/2 groups all the way to the fully depolymerized orthothioborate (BS33–) species. On the basis of these results, a comprehensive and quantitative structural model is developed for these glasses, on the basis of which the compositional trends in the glass transition temperatures (Tg) and ionic conductivities can be rationalized. Up to x = 0.4, the dominant process can be described in a simplified way by the net reaction equation P1 + B1 P0 + B4, where the superscripts denote the number of BS atoms for the respective network former species. Above x = 0.4, all of the thiophosphate units are of the P0 type and both pyro- (B1) and orthothioborate (B0) species make increasing contributions to the network structure with increasing x. In sharp contrast to the situation in sodium borophosphate glasses, four-coordinated thioborate species are generally less abundant and heteroatomic B–S–P linkages appear to not exist. On the basis of this structural information, compositional trends in the ionic conductivities are discussed in relation to the nature of the charge-compensating anionic species and the spatial distribution of the charge carriers

GAMA/G10-COSMOS/3D-HST: The 0<z<5 cosmic star-formation history, stellar- and dust-mass densities

We use the energy-balance code MAGPHYS to determine stellar and dust masses, and dust corrected star-formation rates for over 200,000 GAMA galaxies, 170,000 G10-COSMOS galaxies and 200,000 3D-HST galaxies. Our values agree well with previously reported measurements and constitute a representative and homogeneous dataset spanning a broad range in stellar mass (10^8---10^12 Msol), dust mass (10^6---10^9 Msol), and star-formation rates (0.01---100 Msol per yr), and over a broad redshift range (0.0 < z < 5.0). We combine these data to measure the cosmic star-formation history (CSFH), the stellar-mass density (SMD), and the dust-mass density (DMD) over a 12 Gyr timeline. The data mostly agree with previous estimates, where they exist, and provide a quasi-homogeneous dataset using consistent mass and star-formation estimators with consistent underlying assumptions over the full time range. As a consequence our formal errors are significantly reduced when compared to the historic literature. Integrating our cosmic star-formation history we precisely reproduce the stellar-mass density with an ISM replenishment factor of 0.50 +/- 0.07, consistent with our choice of Chabrier IMF plus some modest amount of stripped stellar mass. Exploring the cosmic dust density evolution, we find a gradual increase in dust density with lookback time. We build a simple phenomenological model from the CSFH to account for the dust mass evolution, and infer two key conclusions: (1) For every unit of stellar mass which is formed 0.0065---0.004 units of dust mass is also formed; (2) Over the history of the Universe approximately 90 to 95 per cent of all dust formed has been destroyed and/or ejected

Height, selected genetic markers and prostate cancer risk:Results from the PRACTICAL consortium

Background: Evidence on height and prostate cancer risk is mixed, however, recent studies with large data sets support a possible role for its association with the risk of aggressive prostate cancer. Methods: We analysed data from the PRACTICAL consortium consisting of 6207 prostate cancer cases and 6016 controls and a subset of high grade cases (2480 cases). We explored height, polymorphisms in genes related to growth processes as main effects and their possible interactions. Results: The results suggest that height is associated with high-grade prostate cancer risk. Men with height 4180cm are at a 22% increased risk as compared to men with height o173cm (OR 1.22, 95% CI 1.01–1.48). Genetic variants in the growth pathway gene showed an association with prostate cancer risk. The aggregate scores of the selected variants identified a significantly increased risk of overall prostate cancer and high-grade prostate cancer by 13% and 15%, respectively, in the highest score group as compared to lowest score group. Conclusions: There was no evidence of gene-environment interaction between height and the selected candidate SNPs. Our findings suggest a role of height in high-grade prostate cancer. The effect of genetic variants in the genes related to growth is seen in all cases and high-grade prostate cancer. There is no interaction between these two exposures.</p

Germline variation at 8q24 and prostate cancer risk in men of European ancestry

Chromosome 8q24 is a susceptibility locus for multiple cancers, including prostate cancer. Here we combine genetic data across the 8q24 susceptibility region from 71,535 prostate cancer cases and 52,935 controls of European ancestry to define the overall contribution of germline variation at 8q24 to prostate cancer risk. We identify 12 independent risk signals for prostate cancer (p < 4.28 × 10−15), including three risk variants that have yet to be reported. From a polygenic risk score (PRS) model, derived to assess the cumulative effect of risk variants at 8q24, men in the top 1% of the PRS have a 4-fold (95%CI = 3.62–4.40) greater risk compared to the population average. These 12 variants account for ~25% of what can be currently explained of the familial risk of prostate cancer by known genetic risk factors. These findings highlight the overwhelming contribution of germline variation at 8q24 on prostate cancer risk which has implications for population risk stratification