Selective electrodeposition of indium microstructures on silicon and their conversion into InAs and InSb semiconductors

Abstract: The idea of benefitting from the properties of III-V semiconductors and silicon on the same substrate has been occupying the minds of scientists for several years. Although the principle of III-V integration on a silicon-based platform is simple, it is often challenging to perform due to demanding requirements for sample preparation rising from a mismatch in physical properties between those semiconductor groups (e.g. different lattice constants and thermal expansion coefficients), high cost of device-grade materials formation and their post-processing. In this paper, we demonstrate the deposition of group-III metal and III-V semiconductors in microfabricated template structures on silicon as a strategy for heterogeneous device integration on Si. The metal (indium) is selectively electrodeposited in a 2-electrode galvanostatic configuration with the working electrode (WE) located in each template, resulting in well-defined In structures of high purity. The semiconductors InAs and InSb are obtained by vapour phase diffusion of the corresponding group-V element (As, Sb) into the liquified In confined in the template. We discuss in detail the morphological and structural characterization of the synthesized In, InAs and InSb crystals as well as chemical analysis through scanning electron microscopy (SEM), scanning transmission electron microscopy (TEM/STEM), and energy-dispersive X-ray spectroscopy (EDX). The proposed integration path combines the advantage of the mature top-down lithography technology to define device geometries and employs economic electrodeposition (ED) and vapour phase processes to directly integrate difficult-to-process materials on a silicon platform. Graphical abstract: [Figure not available: see fulltext.]

A Rheological Model for Cupuassu (Theobroma grandiflorum) Pulp at Different Concentrations and Temperatures

This work was made aiming at studying the best model for the rheological properties of Cupuassu (Theobroma grandiflorum, Schum) pulps with 14 (in nature), 17, 19, 23 and 25°Brix of total soluble solids (TSS) which were me asured at 20, 30, 40, 50 and 60°C temperature using a conc entric cylinder rheometer. The results were adjusted to the following nine models: Ostwald-de-Waele (power law), Bingham, Casson, Generalized Casson, Heinz–Casson, Herschel–Bulkley, Mizrahi–Berk, Schulmann–Haroske–Reher and Windhab. The parameters of the best model were correlated with pulp temperature and TSS by polynomial regression analysis and were kept in the regression equation only those parameters that contributed more than 1% to the variation of the independent variable. The results indicate that the rheological behavior of Cupuassu pulp in different concentrations and temperatures can be modeled by the Windhab model, although other models can be used in a narrower band of shear stress

Synthesis of Morpholine-Based Analogs of (-)-Zampanolide and Their Biological Activity.

We describe the convergent synthesis of three prototypical examples of a new class of analogs of the complex, cytotoxic marine macrolide (-)-zampanolide, which incorporate an embedded N- substituted morpholine moiety in place of the natural tetrahydropyran ring. The final construction of the macrolactone core was based on a high-yielding intramolecular HWE olefination, while the hemiaminal-linked side chain was elaborated through a stereoselective, BINAL-H-mediated addition of ( Z,E )-sorbamide to a macrocyclic aldehyde precursor. The synthesis of the common functionalized morpholine building block involved two consecutive epoxide openings with tosylamide and the product of the first opening reaction, respectively, as nucleophiles. Of the two possible routes departing from two different pairs of enantiomeric epoxides, one proved to be clearly superior. Of the three morpholino-zampanolides investigated, the N- acetyl and the N- benzoyl derivative both exhibited nanomolar antiproliferative activity, thus being essentially equipotent with the natural product. In contrast, the activity of the N- tosyl derivative was significantly reduced