Large-area wet-chemical deposition of nanoporous tungstic silica coatings

We report on a facile procedure for synthesis of nanoporous coatings of tungstic silica through wet-chemical deposition and post-treatment of tungsten-doped potassium silicate solutions. The process relies on an aqueous washing and ion exchange step where dispersed potassium salt deposits are removed from a 150 nm silicate gel layer. Through an adjustment of the pH value of the washing agent within the solubility regime of a tungstic salt precursor, the tungsten content of the remaining nanostructured coating can be controlled. We propose this route as a universal approach for the deposition of large-area coatings of nanoporous silica with the potential for incorporating a broad variety of other dopant species. As for the present case, we observe, on the one hand, antireflective properties which enable the reduction of reflection losses from float glass by up to 3.7 percent points. On the other hand, the incorporation of nanoscale tungstic precipitates provides a lever for tailoring the coating hydrophilicity and, eventually, also surface acidity. This may provide a future route for combining optical performance with anti-fouling functionality

Exploring the limits of the geometric copolymerization model

The geometric copolymerization model is a recently introduced statistical Markov chain model. Here, we investigate its practicality. First, several approaches to identify the optimal model parameters from observed copolymer fingerprints are evaluated using Monte Carlo simulated data. Directly optimizing the parameters is robust against noise but has impractically long running times. A compromise between robustness and running time is found by exploiting the relationship between monomer concentrations calculated by ordinary differential equations and the geometric model. Second, we investigate the applicability of the model to copolymerizations beyond living polymerization and show that the model is useful for copolymerizations involving termination and depropagation reactions

Monitoring the chemistry of self-healing by vibrational spectroscopy - Current state and perspectives

Self-healing materials are designed to heal damage caused by, for example, mechanical stress or aging such that the original functionality of the material is at least partially restored. Thus, self-healing materials hold great promise for prolonging the lifetime of machines, particularly those in remote locations, as well as in increasing the reliability and safety associated with functional materials in, for example, aeronautics applications. Recent material science applications of self-healing have led to an increased interest in the field and, consequently, the spectroscopic characterization of a wide range of self-healing materials with respect to their mechanical properties such as stress and strain resistance and elasticity was in the focus. However, the characterization of the chemical mechanisms underlying various self-healing processes locally within the damaged region of materials still presents a major challenge. This requires experimental techniques that work non-destructively in situ and are capable of revealing the chemical composition of a sample with sufficient spatial and temporal resolution without disturbing the healing process. Along these lines, vibrational spectroscopy and, in particular Raman spectroscopy, holds great promise, largely due to the high spatial resolution in the order of several hundreds of nanometers that can be obtained. This article aims to summarize the state of the art and prospective of Raman spectroscopy to contribute significant insights to the research on self-healing materials - in particular focusing on polymer and biopolymer materials

Ruthenium(II)-bis(4'-(4-ethynylphenyl)-2,2':6', 2''-terpyridine) - A versatile synthon in supramolecular chemistry. Synthesis and characterization

A homoleptic ethynyl-substituted ruthenium(II)-bisterpyridine complex representing a versatile synthon in supramolecular chemistry was synthesized and analyzed by NMR spectroscopy, mass spectrometry and X-ray diffractometry. Furthermore, its photophysical properties were detailed by UV/Vis absorption, emission and resonance Raman spectroscopy. In order to place the results obtained in the context of the vast family of ruthenium coordination compounds, two structurally related complexes were investigated accordingly. These reference compounds bear either no or an increased chromophore in the 4̀-position. The spectroscopic investigations reveal a systematic bathochromic shift of the absorption and emission maximum upon increasing chromophore size. This bathochromic shift of the steady state spectra occurs hand in hand with increasing resonance Raman intensities upon excitation of the metal-to-ligand charge-transfer transition. The latter feature is accompanied by an increased excitation delocalization over the chromophore in the 4̀-position of the terpyridine. Thus, the results presented allow for a detailed investigation of the electronic effects of the ethynyl substituent on the metal-to-ligand charge-transfer states in the synthon for click reactions leading to coordination polymers

Synthesis and Assessment Product

This Climate Change Science Program Synthesis and Assessment Product addresses current capabilities to integrate observations of the climate system into a consistent description of past and current conditions through the method of reanalysis. In addition, the Product assesses present capabilities to attribute causes for climate variations and trends over North America during the reanalysis period, which extends from the mid-twentieth century to the present. This Product reviews the strengths and limitations of current atmospheric reanalysis products. It finds that reanalysis data play a crucial role in helping to identify, describe, and understand atmospheric features associated with weather and climate variability, including high-impact events such as major droughts and floods. Reanalysis data play an important role in assessing the ability of climate models to simulate the average climate and its variations. The data also help in identifying deficiencies in representations of physical processes that produce climate model errors

3D microstructure characterization of polymer battery electrodes by statistical image analysis based on synchrotron X ray tomography

Polymer based batteries represent a promising concept for next generation energy storage due to their potentially higher power densities and smaller ecological footprint, compared to classical Li ion batteries. Since the microstructure of electrodes is a key factor for the performance of battery cells, a detailed understanding of this microstructure is essential for the improvement of manufacturing processes. In the present contribution, the 3D microstructure of electrodes for polymer based batteries is quantitatively characterized for the first time, where synchrotron X ray tomography is combined with statistical image analysis. In particular, 3D imaging is performed for two porous electrodes, which both consist of the redox active polymer PTMA as well as conductive additives, but differ regarding their binder materials. The focus is put on local heterogeneity of volume fractions of the constituents, surface area per unit volume of the polymer phase and the length of shortest transportation paths through both, polymer and binder additive phase. It is shown that using different binder materials leads to significant differences regarding the 3D electrode microstructures. In this way, statistical analysis of image data helps to gain further insight into the influence of manufacturing processes on electrode microstructures and thus, on the performance of battery cell

Some psychological factors associated with illness behavior and selected illnesses

In the expanding field of medical sociology, the frequency of visits to a free medical facility has become an important form of illness behavior. Such behavior not only reflects the individual's physical health, but also his perception of it, and his decision what to do about it. Involved here are also his attitudes toward doctors and medical care, his psychological make-up, and his phenomenological well-being. Various studies have been able to relate the frequency of dispensary visits to such variables as occupational status, self-esteem and self-acceptance, perceived stress, and the readiness to assume the sick role.The present study was concerned with relating the frequency of dispensary visits to the following variables: disturbances of mood (reported well-being) and self-report measures of aggressive tendencies and of control over impulsiveness and over feelings of anger. The same variables were also related to three diagnostic categories: rheumatoid arthritis, hypertension, and ulcer. The major findings, obtained on an industrial population of over 300 male workers, are summarized below: 1. 1. Subjects who obtained high scores on the Mood Scales labeled Aggressive, Jittery, and Depressed had a greater frequency of illness behavior (dispensary visits for illness and illness absences).2. 2. Subjects who scored high on a self-report scale reflecting a tendency to engage in overt aggressive behavior, had a greater frequency of illness behavior.3. 3. The above test and questionnaire data were unrelated to control variables, not indicative of illness behavior: hernia, dispensary visits for injuries, and absences for personal leaves.4. 4. When the measures of control over impulsiveness and over feelings of anger were considered jointly with the other scales, then it was apparent that the amount of control affects the association of illness behavior with mood and overt aggressiveness: strong control reduces the association and weak control enhances it.5. 5. If the scales reflecting tendency to engage in overt aggressive behavior and to control impulsiveness and angry feelings are used to construct a two-dimensional space, then the following placements of the different diagnostic categories are possible: 5.1. (a) Hypertensive men tend to be low on overt aggressiveness and high on control.5.2. (b) Rheumatoid arthritics tend to be high on overt aggressiveness and high on control.5.3. (c) Men with ulcers tend to be low on overt aggressiveness and low on control.5.4. (d) Subjects with a high frequency of illness behavior tend to be high on overt aggressiveness and low on control.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32133/1/0000186.pd