Non-polar ether-based electrolyte solutions for stable high-voltage non-aqueous lithium metal batteries.

The electrochemical instability of ether-based electrolyte solutions hinders their practical applications in high-voltage Li metal batteries. To circumvent this issue, here, we propose a dilution strategy to lose the Li+/solvent interaction and use the dilute non-aqueous electrolyte solution in high-voltage lithium metal batteries. We demonstrate that in a non-polar dipropyl ether (DPE)-based electrolyte solution with lithium bis(fluorosulfonyl) imide salt, the decomposition order of solvated species can be adjusted to promote the Li+/salt-derived anion clusters decomposition over free ether solvent molecules. This selective mechanism favors the formation of a robust cathode electrolyte interphase (CEI) and a solvent-deficient electric double-layer structure at the positive electrode interface. When the DPE-based electrolyte is tested in combination with a Li metal negative electrode (50 µm thick) and a LiNi0.8Co0.1Mn0.1O2-based positive electrode (3.3 mAh/cm2) in pouch cell configuration at 25 °C, a specific discharge capacity retention of about 74% after 150 cycles (0.33 and 1 mA/cm2 charge and discharge, respectively) is obtained.

Validation and Comparison of the Therapeutic Efficacy of Boron Neutron Capture Therapy Mediated By Boron-Rich Liposomes in Multiple Murine Tumor Models.

Boron neutron capture therapy (BNCT) was performed at the University of Missouri Research Reactor in mice bearing CT26 colon carcinoma flank tumors and the results were compared with previously performed studies with mice bearing EMT6 breast cancer flank tumors. Mice were implanted with CT26 tumors subcutaneously in the caudal flank and were given two separate tail vein injections of unilamellar liposomes composed of cholesterol, 1,2-distearoyl-sn-glycer-3-phosphocholine, and K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the lipid bilayer and encapsulated Na3[1-(2`-B10H9)-2-NH3B10H8] within the liposomal core. Mice were irradiated 30 hours after the second injection in a thermal neutron beam for various lengths of time. The tumor size was monitored daily for 72 days. Despite relatively lower tumor boron concentrations, as compared to EMT6 tumors, a 45 minute neutron irradiation BNCT resulted in complete resolution of the tumors in 50% of treated mice, 50% of which never recurred. Median time to tumor volume tripling was 38 days in BNCT treated mice, 17 days in neutron-irradiated mice given no boron compounds, and 4 days in untreated controls. Tumor response in mice with CT26 colon carcinoma was markedly more pronounced than in previous reports of mice with EMT6 tumors, a difference which increased with dose. The slope of the dose response curve of CT26 colon carcinoma tumors is 1.05 times tumor growth delay per Gy compared to 0.09 times tumor growth delay per Gy for EMT6 tumors, indicating that inherent radiosensitivity of tumors plays a role in boron neutron capture therapy and should be considered in the development of clinical applications of BNCT in animals and man.

Direct observation of bis(dicarbollyl)nickel conformers in solution by fluorescence spectroscopy: an approach to redox-controlled metallacarborane molecular motors.

As a continuation of work on metallacarborane-based molecular motors, the structures of substituted bis(dicarbollyl)nickel complexes in Ni(III) and Ni(IV) oxidation states were investigated in solution by fluorescence spectroscopy. Symmetrically positioned cage-linked pyrene molecules served as fluorescent probes to enable the observation of mixed meso-trans/dl-gauche (pyrene monomer fluorescence) and dl-cis/dl-gauche (intramolecular pyrene excimer fluorescence with residual monomer fluorescence) cage conformations of the nickelacarboranes in the Ni(III) and Ni(IV) oxidation states, respectively. The absence of energetically disfavored conformers in solution--dl-cis in the case of nickel(III) complexes and meso-trans in the case of nickel(IV)--was demonstrated based on spectroscopic data and conformer energy calculations in solution. The conformational persistence observed in solution indicates that bis(dicarbollyl)nickel complexes may provide attractive templates for building electrically driven and/or photodriven molecular motors.

Trajectory angle determination in one dimensional single molecule tracking data by orthogonal regression analysis.

The quantitative assessment of single molecule diffusion trajectories by orthogonal regression analysis is reported. This analysis is broadly applicable to any single particle tracking experiments in which diffusion along one dimension (1D) is expected. It affords quantitative data on the (in plane) orientation of 1D trajectories, allowing for their absolute orientations to be determined. Histograms depicting the distribution of trajectory angles provide new physical insights into the degree of trajectory alignment, and by inference, materials order. Estimates of the errors in the trajectory angle and particle positioning along each trajectory are also obtained. The angle results are compared to those from single-step angle determinations. The advantages of the regression method include its simplicity and computational efficiency, and the ability to objectively differentiate between 1D and 2D/immobile trajectories. Its utility is demonstrated through analysis of single molecule diffusion trajectories in surfactant-templated mesoporous silica films as probed by wide-field fluorescence microscopy. The trajectory angle histograms obtained provide quantitative data on mean trajectory orientation and the degree of trajectory alignment in distinct populations and sample regions. Mesopore order was quantitatively assessed by implementation of an order parameter,

= 2-1, calculated from the individual trajectory angles in each of four representative sample regions. The results depict the presence of well-ordered domains (from microns to tens of microns in size), all having

≈ 0.9. The latter corresponds to an ≈14° average deviation of the individual trajectories from the mean trajectory (and mesopore) orientation in each domain.

Electrostatic self-assembly of ordered perylene-diimide/polyelectrolyte nanofibers in fluidic devices: from nematic domains to macroscopic alignment.

Sequential deposition of nanofibrous composites of charged perylene diimide (PDI) dyes and oppositely charged polyelectrolyte (PE) is demonstrated within fluidic devices. The PDIs employed include an amphiphilic, singly charged PDI (C(7)OPDI(+)) and a doubly charged species (TAPDI(2+)). Anionic poly(acrylate) (PA(-), 5100 and 250K MW) is used as the PE. As previously demonstrated [Weitzel, C. R.; Everett, T. A.; Higgins, D. A. Langmuir, 2009, 25, 1188], dip-coated PDI/PE composites form nanofibrous films that exhibit flow-induced alignment due to gravitational draining of the dipping solution. In this study, the potential for producing patterned, flow-aligned PDI/PE composites by deposition using pressure-driven flow within fluidic channels is explored. The influence of flow profile, PE molecular weight (MW) and PDI structure on deposition efficiency, macroscopic and microscopic morphology, and the potential for nanofiber alignment are also investigated. Optical absorbance microscopy and tapping mode AFM data demonstrate that C(7)OPDI(+)/PA(-) deposition is controlled by PDI aggregation, while TAPDI(2+)/PA(-) composites are more dependent upon PE MW. Optical dichroism images show that C(7)OPDI(+)/PA(-) composites form serpentine, partially aligned nanofibers under all conditions explored, while TAPDI(2+)/PA(-) films incorporate more tightly packed nanofibers that form randomly oriented nematic-like domains when high MW PA(-) is employed. In-plane organization in C(7)OPDI(+)/PA(-) films is concluded to result from flow-induced alignment of solution-formed C(7)OPDI(+) aggregates, while the unaligned domains found in TAPDI(2+)/PA(-) films are concluded to form on the substrate surface by the complexation of small TAPDI(2+) aggregates or monomers with PE.

Aggregation and its influence on macroscopic in-plane organization in thin films of electrostatically self-assembled perylene-diimide/polyelectrolyte nanofibers.

The influence of precursor aggregation on materials deposition efficiency, film morphology, and macroscopic in-plane organization is explored for electrostatically self-assembled perylene-diimide/polyelectrolyte (PDI/PE) composites. PDI/PE thin films are prepared from aqueous precursor solutions by sequential dip-coating methods. Three PDI dyes are employed to probe the influence of aggregation on electrostatic self-assembly (ESA) of the composites. These include a singly charged PDI, C(7)OPDI(+), and two doubly charged species, PDISO(3)(2-) and TAPDI(2+). Poly(diallyldimethylammonium) (PDDA(+)) chloride and sodium poly(acrylate) (PA(-)) are used as the PEs. UV-vis absorbance and fluorescence spectroscopies show that all three dyes are heavily aggregated in their respective aqueous solutions. Temperature-dependent fluorescence data and filtration studies show that C(7)OPDI(+) is most strongly associated and also forms the largest aggregates. Absorbance data obtained as a function of the number of deposition cycles employed in film preparation demonstrate that C(7)OPDI(+) is also most efficiently deposited. Atomic force microscopy (AFM) images show that all three PDI/PE films are comprised of similar serpentine nanofibers. Interestingly, bulk absorbance dichroism data and AFM images demonstrate that the C(7)OPDI(+)/PA(-) composites incorporate macroscopically oriented dye and aligned nanofibers. Dye and nanofiber alignment is found to be perpendicular and parallel, respectively, to the dipping direction. No such organization is observed for the other two composites. It is concluded that deposition is strongly influenced by the level of precursor aggregation and that macroscopic in-plane organization in the C(7)OPDI(+)/PA(-) composites results from flow-induced alignment of relatively large preformed C(7)OPDI(+) aggregates during deposition.