Elastic scattering of Ni+Ni near the Coulomb barrier

Elastic scattering angular distributions have been measured for ⁵⁸Ni+⁶⁴Ni at three energies around the Coulomb barrier employing a new kinematic coincidence technique. The data are compared with the results of coupled-channels calculations including inelastic excitations as well as one-and two-neutron transfer reactions. The agreement is good and the calculations also agree well with the available transfer and fusion reaction data.     

In-Situ Adaptive Manifolds: Enabling computationally efficient simulations of complex turbulent reacting flows

Reduced-order manifold approaches to turbulent combustion modeling traditionally involve precomputation of manifold solutions and pretabulation of the thermochemical database versus a small number of manifold variables. However, additional manifold variables are required as the complexity of turbulent combustion processes increases through consideration of, for example, multi-modal, non-adiabatic, or non-isobaric combustion, or combustion featuring multiple and/or inhomogeneous inlets. This increase in the number of manifold variables comes with an increase in the computational cost of precomputing a greater number of manifold solutions, most of which are never actually utilized in a CFD calculation. The memory required to store the pretabulated high-dimensional thermochemical database also increases, practically limiting the complexity of manifold-based combustion models. In this work, a new In-Situ Adaptive Manifolds (ISAM) approach is developed that overcomes this limitation by combining ‘on-the-fly’ calculation of manifold solutions with In-Situ Adaptive Tabulation (ISAT), enabling the use of more complex manifold-based turbulent combustion models. The performance of ISAM is evaluated via LES of turbulent nonpremixed jet flames with both hydrogen and hydrocarbon fuels. A performance assessment indicates that the computational overhead associated with ISAM compared to pretabulation ranges from negligible up to a factor of two, with most of this overhead associated with convolution of the thermochemical state against a presumed subfilter PDF. In addition, the memory requirements of ISAM are more than two orders of magnitude less than conventional tabulation. These results demonstrate the potential for ISAM to accommodate significantly more complex manifold-based combustion models.     

ChemInform Abstract: Evaluation of Tavorite‐Structured Cathode Materials for Lithium‐Ion Batteries Using High‐Throughput Computing.

Tavorite‐structured oxyphosphates, fluorophosphates, oxysulfates, and fluorosulfates are evaluated for use as cathode materials in lithium ion batteries and activation energies for lithium diffusion through LiVO(PO₄), LiV(PO₄)F, and LiFe(SO₄)F are calculated.     

Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C5Me5)3MLn] Nitrile and Isocyanide Complexes

The limits of steric crowding in organometallic metallocene complexes have been examined by studying the synthesis of [(C₅Me₅)₃ML_n] complexes as a function of metal in which L=Me₃CCN, Me₃CNC, and Me₃SiCN. The bis(tert‐butyl nitrile) complexes [(C₅Me₅)₃Ln(NCCMe₃)₂] (Ln=La, 1 ; Ce, 2 ; Pr, 3 ) can be isolated with the largest lanthanide metal ions, La³⁺, Ce³⁺, and Pr³⁺. The Pr³⁺ ion also forms an isolable mono‐nitrile complex, [(C₅Me₅)₃Pr(NCCMe₃)] ( 4 ), whereas for Nd³⁺ only the mono‐adduct [(C₅Me₅)₃Nd(NCCMe₃)] ( 5 ) was observed. With smaller metal ions, Sm³⁺ and Y³⁺, insertion of Me₃CCN into the M? C(C₅Me₅) bond was observed to form the cyclopentadiene‐substituted ketimide complexes [(C₅Me₅)₂Ln{NC(C₅Me₅)(CMe₃)}(NCCMe₃)] (Ln=Sm, 6 ; Y, 7 ). With tert‐butyl isocyanide ligands, a bis‐isocyanide product can be isolated with lanthanum, [(C₅Me₅)₃La(CNCMe₃)₂] ( 8 ), and a mono‐isocyanide product with neodymium, [(C₅Me₅)₃Nd(CNCMe₃)] ( 9 ). Silicon–carbon bond cleavage was observed in reactions between [(C₅Me₅)₃Ln] complexes and trimethylsilyl cyanide, Me₃SiCN, to produce the trimeric cyanide complexes [{(C₅Me₅)₂Ln(μ‐CN)(NCSiMe₃)}₃] (Ln=La, 10 ; Pr, 11 ). With uranium, a mono‐nitrile reaction product, [(C₅Me₅)₃U(NCCMe₃)] ( 12 ), which is analogous to 5 , was obtained from the reaction between [(C₅Me₅)₃U] and Me₃CCN, but [(C₅Me₅)₃U] reacts with Me₃CNC through C? N bond cleavage to form a trimeric cyanide complex, [{(C₅Me₅)₂U(μ‐CN)(CNCMe₃)}₃] ( 13 ).     

Analytical and preparative separation of PEGylated lysozyme for the characterization of chromatography media

The effect of PEGylation on cation exchange chromatography was studied with poly(ethylene glycol) of different chain lengths (5 kDa, 10 kDa and 30 kDa) using lysozyme as a model system. A stable binding via reduction of a Schiff base was formed during random PEGylation on lysine residues with methoxy-PEG-aldehyde. A purification method for PEGylated proteins using cation exchange chromatography was developed, and different isoforms of mono-PEGylated lysozyme were isolated. TSKgel SP-5PW and Toyopearl GigaCap S-650M showed the best performance of all tested cation exchange resins, and the separation of PEGylated lysozyme could be also scaled up to semi-preparative level. Size-exclusion chromatography, SDS-PAGE and MALDI-TOF mass spectrometry were used for analysis. Separated mono-PEGylated lysozyme of different sizes was used to determine dynamic binding capacities (DBC) and selectivity of cation exchange chromatography resins. An optimization of binding conditions resulted in a more than 20-fold increase of DBC for Toyopearl GigaCap S-650M with 30 kDa mono-PEGylated lysozyme.     

Near-barrier fusion of Sn + Ni and Te + Ni systems: examining the correlation between nucleon transfer and fusion enhancement

The fusion excitation functions for radioactive (132)Sn + (58)Ni and stable (130)Te + (58,64)Ni were measured at energies near the Coulomb barrier. The coupling of transfer channels in heavy-ion fusion was examined through a comparison of Sn + Ni and Te + Ni systems, which have large variations in the number of positive Q-value nucleon transfer channels. In contrast with previous experimental comparisons, where increased sub-barrier fusion cross sections were observed in systems with positive Q-value neutron transfer channels, the reduced excitation functions were equivalent for the different Sn + Ni and Te + Ni systems. The present results suggest a dramatically different influence of positive Q-value transfer channels on the fusion process for the Sn + Ni and Te + Ni systems.     

Quantitative sphingosine measurement as a surrogate for total ceramide concentration—preclinical and potential translational applications

Biomarkers are an increasingly important constituent of the drug development process, offering the potential of increased efficiency through reduced compound attrition and earlier proof of mechanism and/or efficacy. Assays developed for compound screening that can be directly translated for clinical trials are especially valuable, but their successful adoption requires a careful balance between assay performance and implementation costs. One such ‘fit‐for‐purpose’ biomarker assay, the indirect measurement of pharmacological modulation of sphingolipid biosynthesis and disposition, is presented here. Among spingolipids, numerous ceramide species are readily detectable in different lipoprotein fractions of mammalian plasma, but their parallel quantification can be prohibitively expensive and time consuming. Ceramides differ in their fatty acid moiety, which is readily removed by hydrolysis, yielding a common sphingosine derivative, the measurement of which serves as an indicator of total ceramide. When followed by liquid chromatography tandem mass spectrometry (LC/MS/MS) for detection, robust analyte quantification becomes relatively straightforward. The practical utility of a method developed to be fit for the purpose of rapidly and quantitatively measuring treatment‐induced variations in total ceramide from hamster plasma and individual lipoprotein fractions is described. With a linear calibration range from 0.003 to 33.4 μm sphingosine, precision and accuracy error in plasma‐based quality controls spiked with ceramides was less than 15%. The specificity of the assay for ceramides was also assessed. The simplicity of the method would allow for its potential translation to other preclinical species, as well as for clinical applications in later‐stage drug development. Copyright © 2009 John Wiley & Sons, Ltd.     

A connection between Strassen's and Donsker-Varadhan's laws of the iterated logarithm

Summary A connection is given between various functional laws of the iterated logarithm for Brownian motion due to Donsker and Varadhan, Csáki, Chung, Strassen, and the author.Supported by an NSF grant