Nematics with quenched disorder: pinning out the origin of memory

Memory effects and glassy behavior have been repeatedly observed in disordered nematic liquid crystals but the connection between these effects and the system topology remained unrevealed. We present an analysis of the local and global topology of the nematic ordering in the presence of quenched disorder and we show that nematics with quenched disorder can be mapped into a system of pinned defect lines and that the memory of the system stems from the pinning of these strings.     

New insights into the seleniranium ion promoted cyclization of prenyl and propenylbenzene aryl ethers

The chromane core is widely represented in nature being part of a wide array of secondary metabolites of plant, fungal, and bacterial origin. In this paper an improved method for the chemical synthesis of differently substituted chromanes is described. Substituted 2H-1-benzopyrans have been synthesized in good to excellent yields (52–81%) by treatment of 3,3-dimethylallyl and propenylbenzene ethers of differently substituted phenols with phenylselenyl chloride.     

Kalman filter deconvolution after cubic splines background removal in the HPLC determination of Cr(III) and Al(III) as 8-hydroxyquinolines

Summary A procedure for the simultaneous quantitation of Al(III) and Cr(III) ions by reversed-phase HPLC, after pre-column complexation with 8-hydroxyquinoline, is described. The deconvolution of the partially overlapped peaks was by the Kalman filter method which yielded accurate and precise results. Background removal from the chromatograms was by a new approach employing cubic splines as interpolators between the peak valleys. Finally, it is shown that the Kalman filter deconvolution, after subtraction of the background by cubic spline interpolation, allowed quantitation of Al(III) and Cr(III) down to 25 ppb for each metal. These concentrations were not detectable by conventional integration methods due to a very low signal-to-noise ratio.     

A numerical experiment of backward erosion piping: kinematics and micromechanics

Meccanica - We report on a numerical experiment by which we investigated the propagation of an erosion pipe in a water saturated granular soil. The simulation was performed with a two-dimensional...     

Kalman filter quantitative resolution of shifted ESCA spectra after optimal alignment by simulated annealing

Summary The quantitative separation of overlapped responses accomplished by the Kalman filter algorithm is deteriorated by the errors in the model due to shifts of the component peaks. This is particularly true for spectral resolution in Electron Spectroscopy for Chemical Analysis (ESCA). A computational approach for the quantitative resolution of overlapping ESCA spectra when there is loss of collinearity between the pure component peaks and the mixture peak, has been developed. The procedure makes itera tive use of the Kalman filter for resolving the mixture spectrum with the component spectra aligned according to some values of the position parameters, and of the simulated annealing algorithm to find the optimal alignment. The performance of simulated annealing in pursuing this task, has been compared with those of simplex and steepest descent, by analyzing a set of overlapped synthetic spectra and some ESCA spectra of powder mixtures of lead compounds.     

Working Memory Decline in Alzheimer’s Disease Is Detected by Complexity Analysis of Multimodal EEG-fNIRS

Alzheimer’s disease (AD) is characterized by working memory (WM) failures that can be assessed at early stages through administering clinical tests. Ecological neuroimaging, such as Electroencephalography (EEG) and functional Near Infrared Spectroscopy (fNIRS), may be employed during these tests to support AD early diagnosis within clinical settings. Multimodal EEG-fNIRS could measure brain activity along with neurovascular coupling (NC) and detect their modifications associated with AD. Data analysis procedures based on signal complexity are suitable to estimate electrical and hemodynamic brain activity or their mutual information (NC) during non-structured experimental paradigms. In this study, sample entropy of whole-head EEG and frontal/prefrontal cortex fNIRS was evaluated to assess brain activity in early AD and healthy controls (HC) during WM tasks (i.e., Rey–Osterrieth complex figure and Raven’s progressive matrices). Moreover, conditional entropy between EEG and fNIRS was evaluated as indicative of NC. The findings demonstrated the capability of complexity analysis of multimodal EEG-fNIRS to detect WM decline in AD. Furthermore, a multivariate data-driven analysis, performed on these entropy metrics and based on the General Linear Model, allowed classifying AD and HC with an AUC up to 0.88. EEG-fNIRS may represent a powerful tool for the clinical evaluation of WM decline in early AD.     

Sustainable Ketalization of Glycerol with Ethyl Levulinate Catalyzed by the Iron(III)-Based Metal-Organic Framework MIL-88A

The catalytic properties of a simple iron-containing MOF based on fumaric acid, MIL-88A, were investigated in the ketalization of ethyl levulinate with glycerol. The corresponding product is a component of current interest as a renewable building block for many uses. Under the following conditions (solventless, 120 °C, stoichiometric ratio, 1% cat.), the reaction proceeds with good yields (85%), and the catalyst can be recovered and recycled without loss of activity, despite some changes in the crystalline lattice and morphology. Moreover, the residual iron content in the product is in the order of units of ppm (≤2), which demonstrates the robustness of the MOF under the reaction conditions.     

Symmetry Breaking and Autocatalytic Amplification in Soai Reaction Confined within UiO-MOFs under Heterogenous Conditions.

Symmetry breaking is observed in the Soai reaction in a confinement environment provided by zirconium-based UiO-MOFs used as crystalline sponges. Subsequent reaction of encapsulated Soai aldehyde with Zn(i-Pr)₂ vapour promoted absolute asymmetric synthesis of the corresponding alkanol. ATR-IR and NMR confirm integration of aldehyde into the porous material, and a similar localization of newly formed chiral alkanol after reaction. Despite the confinement, the Soai reaction exhibits significant activity and autocatalytic amplification. Comparative catalytic studies with various UiO-MOFs indicate different outcomes in terms of enantiomeric excess, handedness distribution of the product and reaction rate, when compared to pristine solid Soai aldehyde, while the crystalline MOF remains highly stable to action of Zn(iPr)₂ vapour. This is an unprecedented example of absolute asymmetric synthesis using MOFs.     

Hints of theta13>0 from global neutrino data analysis

Nailing down the unknown neutrino mixing angle theta{13} is one of the most important goals in current lepton physics. In this context, we perform a global analysis of neutrino oscillation data, focusing on theta{13}, and including recent results [ (unpublished)]. We discuss two converging hints of theta{13}>0, each at the level of approximately 1sigma: an older one coming from atmospheric neutrino data, and a newer one coming from the combination of solar and long-baseline reactor neutrino data. Their combination provides the global estimate sin{2}theta{13}=0.016+/-0.010(1sigma), implying a preference for theta{13}>0 with non-negligible statistical significance ( approximately 90% C.L.). We discuss possible refinements of the experimental data analyses, which might sharpen such intriguing indications.     

A program for evaluating equilibrium constants from spectrophotometric data by non-linear regression analysis

A new program, CFTSP, is described for computing stability constants and molar absorptivities from data on the absorbances of mixtures of a metal ion with a ligand. It is written in FORTRAN 77, can run on personal computers, and has facilities for interactive data analysis and presentation that ease the operator's task in searching for the equilibrium model that best fits the experimental data. A critical evaluation of the performance of the program is presented, and some general criteria for selecting equilibrium parameters, making use of both synthetic and experimental data, are described.