Superconductivity and Electronic Structure of Perovskite MgCNi3

The electronic structure, stability, electron phonon coupling and superconductivity of the non-oxide perovskite MgCNi$_3$ are studied using density functional calculations. The band structure is dominated by a Ni $d$ derived density of states peak just below the Fermi energy, which leads to a moderate Stoner enhancement, placing MgCNi$_3$ in the range where spin fluctuations may noticeably affect transport, specific heat and superconductivity, providing a mechanism for reconciling various measures of the coupling $\lambda$. Strong electron phonon interactions are found for the octahedral rotation mode and may exist for other bond angle bending modes. The Fermi surface contains nearly cancelling hole and electron sheets that give unusual behavior of transport quantities particularly the thermopower. The results are discussed in relation to the superconductivity of MgCNi$_3$.Comment: 4 pages, RevTex, 5 ps figure

Pillared MOFs: structure and ring opening polymerization of cyclic esters

The solvothermal reaction of Zn(NO3)2·6H2O with 5-aminoisophthalic acid and 4,4′-bipyridyl (4,4′-bipy) led to the self-assembly of the known 3-D hybrid H-bonded/covalent structure {[Zn(5-AIP)(4,4′-bipy)0.5]·DMF}n (1·DMF), but with DMF here (rather than H2O as previously): an analogous reaction using the related 4,4′-azopyridine (4,4′-azopy) in place of 4,4′-bipyridyl afforded the structurally related framework {[Zn(5-AIP)(4,4′-azopy)0.5]·0.75DMF}n (2·0.75DMF). Similar solvothermal reactions of Co(NO3)·6H2O, Mn(NO3)·4H2O and Cd(NO3)·4H2O with 5-aminoisophthalate and the potential linkers 4,4′-bipy, 2-di(4-pyridyl)ethylene (DPE), and 4,4′-azopy afforded the porous 3-D structures {[Co2(NO3)2(5-AIP)(4,4′-bipy)2]·2EtOH}n (3·2EtOH), {[Co(5-AIP)(DPE)]·2DMF}n (4·2DMF), {[Co(5-AIP)(4,4′-azopy)]·2DMA}n (5·2DMA), {[Mn(5-AIP)(4,4′-bipy)]·2DMA}n (6·2DMA), {[Mn(5-AIP)(DPE)]·6DMF}n (7·6DMF), {[Mn(5-AIP)(4,4′-azopy)]·2.5DMF}n (8·2.5DMF), the previously reported {[Cd(5-AIP)(4,4′-bipy)]·3DMF}n (9·3DMF), {[Cd(5-AIP)(DPE)]·DMF}n (10), and {Cd(5-AIP)(4,4′-azopy)(DMF)}n (11), with structures 4-10 bearing the same network topologies with metal atoms and 5-AIP ligands in sheets, bipy ligands acting as pillars, and solvent molecules of crystallisation located around the bipy ligands. The activated MOFs were employed as catalysts for the ring opening polymerization (ROP) of ϵ-caprolactone and δ-valerolactone. ROPs were conducted as melts, and under N2 only 1 with δ-VL (∼93% conversion) was active. In the case of ϵ-CL under air, all the systems were active with 1, 2, and 11 affording >90% conversion. Molecular weights (Mn) were in the range 3760-17 940 Da and the products formed were identified as both cyclic and linear PCL. For δ-VL, the catalysts performed somewhat better, with all systems (except 8) affording ∼90% conversion or more under air. Molecular weights (Mn) were in the range 2180-7940 and as for PCL, the products formed were identified as both cyclic and linear PCL

Quantum control of 88^{88}Sr+^+ in a miniature linear Paul trap

We report on the construction and characterization of an apparatus for quantum information experiments using $^{88}$Sr$^+$ ions. A miniature linear radio-frequency (rf) Paul trap was designed and built. Trap frequencies above 1 MHz in all directions are obtained with 50 V on the trap end-caps and less than 1 W of rf power. We encode a quantum bit (qubit) in the two spin states of the $S_{1/2}$ electronic ground-state of the ion. We constructed all the necessary laser sources for laser cooling and full coherent manipulation of the ions' external and internal states. Oscillating magnetic fields are used for coherent spin rotations. High-fidelity readout as well as a coherence time of 2.5 ms are demonstrated. Following resolved sideband cooling the average axial vibrational quanta of a single trapped ion is $\bar n=0.05$ and a heating rate of $\dot{\bar n}=0.016$ ms$^{-1}$ is measured.Comment: 8 pages,9 figure

The solution of nonlinear boundary-value transport problems in electron and plasma devices

A method of solution of the nonlinear Landau-Vlasov equation which occurs in charged particle transport phenomena is described. The method is similar in concept to the Spherical Harmonics Method of neutron transport theory, since the particle distribution function is expanded in orthogonal functions of velocity to obtain an infinite set of partial differential equations. The nonlinearity arises when the particle interactions are taken into account in the force term of the Landau-Vlasov equation. The latter is introduced into the equation iteratively and a numerical integration routine is described to integrate the set of equations resulting from a finite (nth order) truncation of the expansion. The truncated equations, which are for the first n velocity moments of the distribution function, are such that these moments satisfy the untruncated equations also, whereas higher moment equations are modified by a fictitious source term. The convergence of the finite-difference equations and the convergence of the finite-difference solution to the solution of the differential equations is proved for the linear case in which the force is assumed to be known. Computational evidence of the convergence in the nonlinear case is provided, although no mathematical proof has so far been developed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33476/1/0000881.pd

Unified concepts for understanding and modelling turnover of dissolved organic matter from freshwaters to the ocean: the UniDOM model

The transport of dissolved organic matter (DOM) across the land-ocean-aquatic continuum (LOAC), from freshwater to the ocean, is an important yet poorly understood component of the global carbon budget. Exploring and quantifying this flux is a significant challenge given the complexities of DOM cycling across these contrasting environments. We developed a new model, UniDOM, that unifies concepts, state variables and parameterisations of DOM turnover across the LOAC. Terrigenous DOM is divided into two pools, T1 (strongly-UV-absorbing) and T2 (non- or weakly-UV-absorbing), that exhibit contrasting responses to microbial consumption, photooxidation and flocculation. Data are presented to show that these pools are amenable to routine measurement based on specific UV absorbance (SUVA). In addition, an autochtonous DOM pool is defined to account for aquatic DOM production. A novel aspect of UniDOM is that rates of photooxidation and microbial turnover are parameterised as an inverse function of DOM age. Model results, which indicate that ~5% of the DOM originating in streams may penetrate into the open ocean, are sensitive to this parameterisation, as well as rates assigned to turnover of freshly produced DOM. The predicted contribution of flocculation to DOM turnover is remarkably low, although a mechanistic representation of this process in UniDOM was considered unachievable because of the complexities involved. Our work highlights the need for ongoing research into the mechanistic understanding and rates of photooxidation, microbial consumption and flocculation of DOM across the different environments of the LOAC, along with the development of models based on unified concepts and parameterisations

Ação do cepa e do ácido giberélico na frutificação da videira 'niagara rosada'

Studies were carried out to establish the effects of exogenous growth regulators on Vitis (labrusca x vinifera) 'Niagara Rosada' fruiting. The investigations were done in the Jundiaí Research Station, Agronomic Institute State of São Paulo, always using disease-free vineyards of good productivity. The morphological transformations of clusters were carried out under the following aspects: weight, length and width of cluster; number of berries; weight, length average and width average of berries; length average/width average ratio of berries; number of seeds; length and diameter of secondary rachis. That characteristics were determined at the time of maturity plus the total sugars, total acid, Maturity Index and reducing sugars in samples of all treatments. The experiment were conduced in order to determine the doses that resulted in the most beneficial effects, always using applications by immersion of the inflorescence. The experiment consisted of appplications of (2-chloroethyl) phosphonic acid (CEPA) at concentrations of 50, 100, 250, 500, 1,000 and 2,000 ppm, 14 days before flowering; treatments with gibberellic acid at concentrations of 100 and 200 ppm before full bloom, 10 days after full bloom, and both before plus after full bloom. Treatment with CEPA 100 ppm plus gibberellic acid 100 ppm before full bloom and check treatment were also used. The use of CEPA before flowering at the concentrations used, did not result in good results in 'Niagara Rosada' clusters; applications of gibberellic acid did not differ significantly from the nontreated vines under the conditions studied.Estudou-se o efeito da aplicação, por imersão, do CEPA (ácido 2-cloroetil fosfônico) e do ácido giberélico, 14 dias antes do florescimento, nas características morfológicas da panícula da videira Vitis (labrus-ca x vinifera) "Niagara Rosada". Alguns tratamentos com ácido giberélico foram concluídos com nova aplicação 10 dias após o florescimento. Neste experimento verificou-se que, aplicação do CEPA na concentração de 250 ppm resultou na formação de panículas com a maioria de características indesejáveis. o tratamento misto CEPA 100 ppm + ácido giberélico 100 ppm também promoveu o aparecimento de panículas subdesenvolvidas. Aplicação de ácido giberélico na concentração de 100 ppm em pré e pós-ílorescimento, resultou médias mais elevadas, com relação ao peso da panícula, comprimento da panícula, peso das bagas e comprimento da ráquis. Ácido giberélico na concentração de 100 ppm aplicado em pós-ílorescimento, promoveu uma tendência de aumento nas médias do tratamento quanto ao comprimento médio das bagas, largura média das bagas, largura do engaço e comprimento da ráquila. Devemos considerar porém, que os resultados obtidos não apresentaram diferenças significativas com relação ao controle, quanto às características das frutificações, nas condições de estudo

Measurement of single pi0 production in neutral current neutrino interactions with water by a 1.3 GeV wide band muon neutrino beam

Neutral current single pi0 production induced by neutrinos with a mean energy of 1.3 GeV is measured at a 1000 ton water Cherenkov detector as a near detector of the K2K long baseline neutrino experiment. The cross section for this process relative to the total charged current cross section is measured to be 0.064 +- 0.001 (stat.) +- 0.007 (sys.). The momentum distribution of produced pi0s is measured and is found to be in good agreement with an expectation from the present knowledge of the neutrino cross sections.Comment: 6 pages, 4 figures, Submitted to Phys. Lett.

Calibrating and adjusting expectations in life: A grounded theory on how elderly persons with somatic health problems maintain control and balance in life and optimize well-being

Aim: This study aims at exploring the main concern for elderly individuals with somatic health problems and what they do to manage this. Method: In total, 14 individuals (mean = 74.2 years; range = 68–86 years) of both gender including hospitalized and outpatient persons participated in the study. Open interviews were conducted and analyzed according to grounded theory, an inductive theory-generating method. Results: The main concern for the elderly individuals with somatic health problems was identified as their striving to maintain control and balance in life. The analysis ended up in a substantive theory explaining how elderly individuals with somatic disease were calibrating and adjusting their expectations in life in order to adapt to their reduced energy level, health problems, and aging. By adjusting the expectations to their actual abilities, the elderly can maintain a sense of that they still have the control over their lives and create stability. The ongoing adjustment process is facilitated by different strategies and result despite lower expectations in subjective well-being. The facilitating strategies are utilizing the network of important others, enjoying cultural heritage, being occupied with interests, having a mission to fulfill, improving the situation by limiting boundaries and, finally, creating meaning in everyday life. Conclusion: The main concern of the elderly with somatic health problems was to maintain control and balance in life. The emerging theory explains how elderly people with somatic health problems calibrate their expectations of life in order to adjust to reduced energy, health problems, and aging. This process is facilitated by different strategies and result despite lower expectation in subjective well-being