Fluctuation Transmission Electron Microscopy: Detecting Nanoscale Order in Disordered Structures

The structures of many disordered materials are not ideally random, but contain structural order on the scale of 1–3 nm. However, such nanoscale order, called medium‐range order, cannot be detected by conventional diffraction methods in most cases. Fluctuation transmission electron microscopy (FTEM) has the capability to detect medium‐range order in disordered materials based on statistical analysis of nanodiffraction patterns or dark‐field images from TEM. FTEM has been successful in demonstrating the theoretically predicted development of nanoscale nuclei in amorphous chalcogenides, as well as in revealing the subtle effect of different preparation routes on the medium‐range order in amorphous semiconductors and metals. The fluctuation principle can also be applied to study structural order on longer length scales in polymers and other disordered materials using X‐rays or visible light. Further advances in theory and practice of FTEM will greatly increase our understanding of amorphous structures and nucleation phenomena.     

Alkali metal counterion control of enolate protonation stereoselectivity

[reaction: see text] Generation of the lithium salt of the norbornenol shown (M = H) followed by quenching with aqueous NH(4)Cl solution gives predominantly the beta-epimeric ketone 6. Similar production of the potassium alkoxide leads instead to the alpha-epimer (99:1). These results reveal the potential importance of alkali metal counterions as stereocontrol elements.     

Optimal Angle Bounds for Quadrilateral Meshes

We show that any simple planar n-gon can be meshed in linear time by O(n) quadrilaterals with all new angles bounded between 60 and 120 degrees.     

Potentiometric and voltammetric polymer lab chip sensors for determination of nitrate, pH and Cd(II) in water

Microparticles are phospholipid vesicles shed mostly in biological fluids, such as blood or urine, by various types of cells, such as red blood cells (RBCs), platelets, lymphocytes, endothelial cells. These microparticles contain a subset of the proteome of their parent cell, and their ready availability in biological fluid has raised strong interest in their study, as they might be markers of cell damage. However, their small size as well as their particular physico-chemical properties makes them hard to detect, size, count and study by proteome analysis. In this review, we report the pre-analytical and methodological caveats that we have faced in our own research about red blood cell microparticles in the context of transfusion science, as well as examples from the literature on the proteomics of various kinds of microparticles.     

Invariances of frame sequences under perturbations

This paper determines the exact relationships that hold among the major Paley-Wiener perturbation theorems for frame sequences. It is shown that major properties of a frame sequence such as excess, deficit, and rank remain invariant under Paley-Wiener perturbations, but need not be preserved by compact perturbations. For localized frames, which are frames with additional structure, it is shown that the frame measure function is also preserved by Paley-Wiener perturbations.     

Corrigenda and addenda to vibrational spacings for H2 +, D2 + and H2

A detailed study of the low temperature absorption spectra of some 16 molecular crystals containing Ni(H₂O)₆ ⁺⁺ has allowed us to identify the electronic and vibrational origins of the ‘red’ absorption band. A complete band contour analysis has been performed, which makes possible a discussion of the crossing of the ¹Γ₃ and ³Γ₃ levels.     

Enhanced long-term stability of bismuth oxide-based electrolytes for operation at 500 °C

Cubic-stabilized ((DyO_1.5) _x –(WO₃) _y –(BiO_1.5)_{1 − x − y} ) electrolytes (DWSB) with much higher conductivity than (ErO_1.5)_0.2(BiO_1.5)_0.8, 20ESB, were developed through a double-doping strategy. (DyO_1.5)_0.08–(WO₃)_0.04–(BiO_1.5)_0.88, 8D4WSB, is the highest conductivity composition but underwent the greatest conductivity degradation at 500 °C due to its low total dopant concentration. The effect of dopant composition on conductivity behavior with time at 500 °C demonstrates that there is a trade-off between initial conductivity and long-term stability at this temperature. Therefore, it is necessary to find an optimal total and relative concentration of dopants to provide the enhanced long-term stability needed to make this DWSB electrolyte system feasible for 500 °C operation. To this end, it was found that (DyO_1.5)_0.25–(WO₃)_0.05–(BiO_1.5)_0.70, 25D5WSB, maintained a conductivity of 0.0068 S/cm without appreciable degradation after annealing at 500 °C for 500 h. Moreover, since bismuth oxide-based electrolytes do not exhibit any grain boundary impedance, the total conductivity of 25D5WSB is significantly higher than that of alternate electrolytes (e.g., GDC: Gd_0.1Ce_0.9O_1.95) at this temperature.     

Conformal Mapping in Linear Time

We show that any simple planar n-gon can be meshed in linear time by O(n) quadrilaterals with all new angles bounded between 60 and 120 degrees.     

A quasisymmetric surface with no rectifiable curves

There is a quasiconformal mapping of to itself such that the image of contains no rectifiable curves.