Li-ion batteries from LiFePO4 cathode and anatase/graphene composite anode for stationary energy storage

Li-ion batteries made from LiFePO₄ cathode and anatase TiO₂/graphene composite anode were investigated for potential application in stationary energy storage. Fine-structured LiFePO₄ was synthesized by a novel molten surfactant approach whereas anatase TiO₂/graphene nanocomposite was prepared via self-assembly method. The full cell that operated at 1.6 V demonstrated negligible fade even after more than 700 cycles at measured 1 C rate. While with relative lower energy density than traditional Li-ion chemistries interested for vehicle applications, the Li-ion batteries based on LiFePO₄/TiO₂ combination potentially offers long life and low cost, along with safety, all which are critical to the stationary applications.     

In situ measurement of biaxial modulus of Si anode for Li-ion batteries

We report in situ measurement of biaxial moduli of a Si thin-film electrode as a function of its lithium concentration. During lithiation, biaxial compressive stress is induced in the Si film and it undergoes plastic flow. At any state-of-charge (SOC), a relatively small delithiation–relithiation sequence unloads and reloads the film elastically. From the stress and strain changes during a delithiation–relithiation cycle, the biaxial modulus of the film is calculated. Stress change is obtained by measuring the change in substrate curvature using a Multi-beam Optical Sensor; the elastic strain change is obtained from the change in SOC. By repeating these measurements at several different values of SOC, the biaxial modulus was seen to decrease from ca. 70 GPa for Li_0.32Si to ca. 35 GPa for Li_3.0Si. Such a significant reduction in elastic modulus has important implications for modeling stress evolution and mechanical degradation in Si-based anodes.     

Evaluation of standard and advanced preprocessing methods for the univariate analysis of blood serum 1H-NMR spectra

Proton nuclear magnetic resonance (¹H-NMR)-based metabolomics enables the high-resolution and high-throughput assessment of a broad spectrum of metabolites in biofluids. Despite the straightforward character of the experimental methodology, the analysis of spectral profiles is rather complex, particularly due to the requirement of numerous data preprocessing steps. Here, we evaluate how several of the most common preprocessing procedures affect the subsequent univariate analyses of blood serum spectra, with a particular focus on how the standard methods perform compared to more advanced examples. Carr–Purcell–Meiboom–Gill 1D ¹H spectra were obtained for 240 serum samples from healthy subjects of the Asklepios study. We studied the impact of different preprocessing steps—integral (standard method) and probabilistic quotient normalization; no, equidistant (standard), and adaptive-intelligent binning; mean (standard) and maximum bin intensity data summation—on the resonance intensities of three different types of metabolites: triglycerides, glucose, and creatinine. The effects were evaluated by correlating the differently preprocessed NMR data with the independently measured metabolite concentrations. The analyses revealed that the standard methods performed inferiorly and that a combination of probabilistic quotient normalization after adaptive-intelligent binning and maximum intensity variable definition yielded the best overall results (triglycerides, R = 0.98; glucose, R = 0.76; creatinine, R = 0.70). Therefore, at least in the case of serum metabolomics, these or equivalent methods should be preferred above the standard preprocessing methods, particularly for univariate analyses. Additional optimization of the normalization procedure might further improve the analyses.     

Variable denticity in carboxylate binding to the uranyl coordination complexes

Tris-carboxylate complexes of uranyl [UO₂]²⁺ with acetate and benzoate were generated using electrospray ionization mass spectrometry, and then isolated in a Fourier transform ion cyclotron resonance mass spectrometer. Wavelength-selective infrared multiple photon dissociation (IRMPD) of the tris-acetato uranyl anion resulted in a redox elimination of an acetate radical, which was used to generate an IR spectrum that consisted of six prominent absorption bands. These were interpreted with the aid of density functional theory calculations in terms of symmetric and antisymmetric −CO₂ stretches of the monodentate and bidentate acetate, CH₃ bending and umbrella vibrations, and a uranyl O—U—O asymmetric stretch. The comparison of the calculated and measured IR spectra indicated that the predominant conformer of the tris-acetate complex contained two acetate ligands bound in a bidentate fashion, while the third acetate was monodentate. In similar fashion, the tris-benzoate uranyl anion was formed and photodissociated by loss of a benzoate radical, enabling measurement of the infrared spectrum that was in close agreement with that calculated for a structure containing one monodentate and two bidentate benzoate ligands.     

Molecular conductors with differently oriented conducting layers, (EDT-TTF)3Hg2Br6 and (TMBEDT-TTF)5Hg(SCN)4-xIx

New conducting radical cation salts (EDT-TTF)₃Hg ₂Br6, (TMET) ₅Hg(SCN) _4-xI_x (x≈0.35), and (EDT-TTF)₃Hg(SCN)₃I_0.5(PhCl)_0.5 were synthesized. Their conductivities, ESR and polarized reflectance spectra were studied. It was shown that the organic conductors with differently oriented conducting layers (EDT-TTF)₃Hg₂Br₆ and (TMET)₅Hg(SCN)_4-xI_x (x≈?0.35) are characterized by the quasi-one-dimensional character of electron motion. The conductivity along and across conducting layers has a semiconductive character. It was established by ESR and polarized reflectance spectroscopy that the properties of such conductors are a superposition of the properties of individual conducting layers.     

In situ investigations of vault paintings in the Antwerp cathedral

X-ray fluorescence spectroscopy (XRF) and Raman spectroscopy have been used to examine 15th century mediaeval and 16th century renaissance vault paintings in the Our Lady's Cathedral (Antwerp, Belgium) in view of their restoration. The use of mobile instruments made it possible to work totally non-destructively. This complementary approach yields information on the elemental (XRF) and on the molecular composition (Raman) of the pigments. For the 15th century vault painting the pigments lead–tin yellow (Pb₂SnO₄), lead white (2PbCO₃·Pb(OH)₂), vermilion (HgS), massicot (PbO) and azurite (2CuCO₃·Cu(OH)₂) could be identified. The pigments used for the 16th century vault painting could be identified as red lead (Pb₃O₄), hematite (Fe₂O₃), lead white (2PbCO₃·Pb(OH)₂) and azurite (2CuCO₃·Cu(OH)₂). For both paintings the presence of the strong Raman scatterer calcite (CaCO₃) resulted in a difficult identification of the pigments by Raman spectroscopy. The presence of gypsum (CaSO₄·2H₂O) on the mediaeval vault painting probably indicates that degradation took place.     

Synthesis,Spectroscopy, Crystal Structure Determination,and Quantum Chemical Calculations of BODIPY Dyes with Increasing Conformational Restriction and Concomitant Red‐Shifted Visible Absorption and Fluorescence Spectra

Starting from the conformationally unconstrained compound 3,5‐di‐(2‐bromophenoxy)‐4,4‐difluoro‐8‐(4‐methylphenyl)‐4‐bora‐3a,4a‐diaza‐s‐indacene ( 1 ), two BODIPY dyes ( 2 and 3 ) with increasingly rigid conformations were synthesized in outstanding total yields through palladium catalyzed intramolecular benzofuran formation. Restricted bond rotation of the phenoxy fragments leads to dyes 2 and 3 , which absorb and fluoresce more intensely at longer wavelengths relative to the unconstrained dye 1 . Reduction of the conformational flexibility in 2 and 3 leads to significantly higher fluorescence quantum yields compared to those of 1 . X‐ray diffraction analysis shows the progressively more extended planarity of the chromophore in line with the increasing conformational restriction in the series 1 → 2 → 3 , which explains the larger red shifts of the absorption and emission spectra. These conclusions are confirmed by quantum chemical calculations of the lowest electronic excitations in 1 , 1a , 2 , 2a , 3 and dyes of related chemical structures. The effect of the molecular structure on the visible absorption and fluorescence emission properties of 1 , 1a , 2 , 2a , 3 has been examined as a function of solvent by means of the new, generalized treatment of the solvent effect (J. Phys. Chem. B 2009 , 113, 5951–5960). Solvent polarizability is the primary factor responsible for the small solvent‐dependent shifts of the visible absorption and fluorescence emission bands of these dyes.     

Pharmacological interactions of essential oil constituents on the viability of micro-organisms

Complex interactions between numerous components of essential oils often contribute to the pharmacological effect and therapeutic outcome. To further elucidate these interactions, several essential oil constituents (EOCs) were combined in different ratios and their inhibitory effects on the growth of bacteria and yeast determined using the minimum inhibitory concentration (MIC) microplate assay. When combined and tested against Candida albicans, (+)-beta-pinene interacted antagonistically with (-)-menthone (sigmaFIC(T) = 9.80), but synergistically with 1,8-cineole (sigmaFIC(T) = 0.35). Against Escherichia coli, the combination of E- and Z-(+/-)-nerolidol and geranyl acetate displayed an additive interaction (sigmaFIC(T) = 1.04); while a variable interaction was observed between E- and Z-(+/-)-nerolidol and eugenol with antagonism and synergy being observed at different ratios of each EOC. The combination of either carvacrol or eugenol with an antimicrobial agent (ciprofloxacin or amphotericin B) resulted in synergistic interactions against all microorganisms tested. These favourable results further support the use of essential oil constituents as adjuvants in the development of a new generation of phytopharmaceuticals that can be used in combination with synthetic drugs against drug-resistant microorganisms.     

A rapid and sensitive CE method with field-enhanced sample injection and in-capillary derivatization for selenomethionine metabolism catalyzed by flavin-containing monooxygenases

A rapid and sensitive electrophoretically mediated microanalysis method with field-enhanced sample injection (FESI) for in-capillary derivatization was developed to determine selenomethionine (SeMet) and selenomethionine selenoxide (SeOMet). Phthalic anhydride (PA) was selected as the derivatization reagent due to the fast reaction at room temperature and the stability of derivatives. The in-capillary derivatization was accomplished by electrophoretically mixing PA and sample plugs. PA reagent was introduced hydrodynamically into the capillary, whereas the sample solution was injected electrokinetically, thus allowing a selective preconcentration of the analytes by FESI. For FESI, the optimum sample solvent was 2 mM borate solution. The borate buffer was suitable for both in-capillary derivatization and separation of the derivatives. The combination of electrophoretically mediated microanalysis with FESI for in-capillary derivatization was successfully achieved with about 800-fold concentration sensitivity enhancement compared to direct CE-UV detection in the same setup. The present method is miniaturized and fully automated, which ensures the on-line derivatization, stacking, separation and detection in 10 min. Finally, the developed method was successfully applied to measure enzyme activities by analyzing the reaction mixtures of SeMet with human flavin-containing monooxygenases (FMO). The results showed that both FMO1 and FMO3, but not FMO5 could catalyze the Se-oxygenation of SeMet.     

Microstructural characterization of SLS-PA12 specimens under dynamic tension/compression excitation

This paper describes the effect of dynamic tension/compression loading on selective laser sintered components in polyamide. To gain more insight in the fatigue phenomena, both thermal and microstructural studies were performed on the fracture surfaces of the test specimens. The presented micrographs, DSC curves, hysteresis loops and S/N-line facilitate an improved understanding of the fatigue properties of selective laser sintered materials, polyamide in particular. The results show that crack initiation starts from inclusions in the material caused by unfused powder particles. The inclusions give rise to the formation of semi-spherical depressions with raised edges. Ductile fatigue striations were noted on the sides of these depressions indicating the irreversible plastic deformation dominated by shear stress, which is typical for fatigue failure. Consequently, microstructural analysis indicates that the material density is a crucial factor influencing the fatigue life of SLS-PA12 components. The lower the density, the more unfused powder particles and the higher the chance of crack initiation.