Conductive macroporous composite chitosan-carbon nanotube scaffolds

Multiwalled carbon nanotubes (MWCNTs) were used as doping material for three-dimensional chitosan scaffolds to develop a highly conductive, porous, and biocompatible composite material. The porous and interconnected structures were formed by the process of thermally induced phase separation followed by freeze-drying applied to an aqueous solution of 1 wt % chitosan acetic acid. The porosity was characterized to be 97% by both mercury intrusion porosimetry measurements and SEM image analysis. When MWCNTs were used as a filler to introduce conductive pathways throughout the chitosan skeleton, the solubilizing hydrophobic and hydrophilic properties of chitosan established stable polymer/MWCNT solutions that yielded a homogeneous distribution of nanotubes throughout the final composite matrix. A percolation theory threshold of approximately 2.5 wt % MWCNTs was determined by measurement of the conductivity as a function of chitosan/MWCNT ratios. The powder resistivity of completely compressed scaffolds also was measured and was found to be similar for all MWCNT concentrations (0.7-0.15 Omega cm powder resistivity for MWCNTs of 0.8-5 wt %) and almost five times lower than the 20 k Omega cm value found for pure chitosan scaffolds.     

Identities with involution for the matrix algebra of order two in characteristic<Emphasis Type="Italic">p</Emphasis>

LetM ₂ (K) be the matrix algebra of order two over an infinite fieldK of characteristicp≠2. IfK is algebraically closed then, up to isomorphism, there are two involutions of first kind onM ₂ (K), namely the transpose and the symplectic. IfK is not algebraically closed, studying *-identities it is still sufficient to consider only these two involutions. We describe bases of the polynomial identities with involution in each of these cases. Supported by PhD grant from CNPq. Partially supported by CNPq and by CAPES.     

A convergent,scalable and stereoselective synthesis of azole CYP51 inhibitors

The study and development of azole-based CYP51 inhibitors is an active area of research across disciplines of biochemistry, pharmacology and infectious disease. Support of in vitro and in vivo studies require the development of robust asymmetric routes to single enantiomer products of this class of compounds. Herein, we describe a scalable and enantioselective synthesis to VNI and VFV, the two potent inhibitors of protozoan sterol 14α-demethylase (CYP51) that are currently under consideration for clinical trials for Chagas disease. A key transformation is the Jacobsen Hydrolytic Kinetic Resolution (HKR) reaction. The utility of the synthetic route is illustrated by the preparation of >25 g quantities of single enantiomers of VNI and VFV.     

The trigonometric Grassmannian and a difference W-algebra

We introduce a W-algebra which is a central extension of the Lie algebra of difference operators with rational coefficients acting on functions of a discrete variable. We construct its natural fermionic and bosonic representations. We define a module over this difference W-algebra, which characterizes the trigonometric Calogero–Moser spaces.     

The X-Ray Transform for a Generic Family of Curves and Weights

We study the weighted integral transform on a compact manifold with boundary over a smooth family of curves Γ. We prove generic injectivity and a stability estimate under the condition that the conormal bundle of Γ covers T ^* M. Second author was partly supported by NSF Grant DMS-0400869; third author was partly supported by NSF and a Walker Family Endowed Professorship.     

Extracting biological information with computational analysis of Fourier-transform infrared (FTIR) biospectroscopy datasets: current practices to future perspectives

Applying Fourier-transform infrared (FTIR) spectroscopy (or related technologies such as Raman spectroscopy) to biological questions (defined as biospectroscopy) is relatively novel. Potential fields of application include cytological, histological and microbial studies. This potentially provides a rapid and non-destructive approach to clinical diagnosis. Its increase in application is primarily a consequence of developing instrumentation along with computational techniques. In the coming decades, biospectroscopy is likely to become a common tool in the screening or diagnostic laboratory, or even in the general practitioner's clinic. Despite many advances in the biological application of FTIR spectroscopy, there remain challenges in sample preparation, instrumentation and data handling. We focus on the latter, where we identify in the reviewed literature, the existence of four main study goals: Pattern Finding; Biomarker Identification; Imaging; and, Diagnosis. These can be grouped into two frameworks: Exploratory; and, Diagnostic. Existing techniques in Quality Control, Pre-processing, Feature Extraction, Clustering, and Classification are critically reviewed. An aspect that is often visited is that of method choice. Based on the state-of-art, we claim that in the near future research should be focused on the challenges of dataset standardization; building information systems; development and validation of data analysis tools; and, technology transfer. A diagnostic case study using a real-world dataset is presented as an illustration. Many of the methods presented in this review are Machine Learning and Statistical techniques that are extendable to other forms of computer-based biomedical analysis, including mass spectrometry and magnetic resonance.