Progesterone crystallization from a solvent: a new procedure

We have grown progesterone single crystals from a gradually heated solution in acetone + ethyl ether. Transparent crystals obtained were analyzed by X-ray diffraction, electron diffraction, infrared and Raman spectroscopy. The X-ray and electron diffraction show an orthorhombic structure. Spectroscopy confirms that the crystal is constituted by the same components as the progesterone molecule. Electronic Publication     

Method for the estimation of the mean lorentzian bandwidth in spectra composed of an unknown number of highly overlapped bands

We introduce a method for the estimation of the mean Lorentzian bandwidth of the component bands in a spectrum. The method is computationally simple, using only the module of the Fourier transform of the spectrum, and its first derivative. Moreover, the presented method does not require knowledge of the number of bands in the spectrum, their band positions, or their band areas. Furthermore, it works on spectra containing Lorentzian bands, as well as Gaussian and Voigtian bands. Therefore, the introduced method seems especially well suited for obtaining a representative Lorentzian width for highly overlapped bands, independent of their number and Lorentzian/Gaussian character. We describe how different experimental limitations (spectral truncation, offset error, presence of noise, etc.) may affect the performance of the method, and when required we propose effective alternatives to minimize their effects. Finally, we show the application of the method to an experimental spectrum: the amide I band of a dry film of the solubilized ADP/ATP carrier. The estimation of the mean Lorentzian width can allow, for instance, for a more objective selection of the deconvolution width in Fourier self-deconvolution, allowing for a more objective and reliable analysis of the amide I band of proteins. The mean Lorentzian width can also be useful to obtain an estimation of the homogenous broadening and vibrational relaxation of the amide I vibration of proteins, without requiring complex pump-probe experiments.     

Magnetic beads based immunoaffinity capillary electrophoresis of total serum IgE with laser-induced fluorescence detection

A magnetic beads based immunoaffinity capillary electrophoresis method for total Immunoglobulin E quantification in serum has been developed. The method combines speed, automation ability, and minimal sample consumption. Only 1 microL of serum is required while the whole immunoaffinity capillary electrophoresis method is performed in less than 50 min. The concomitant use of online immunocapture, transient isotachophoresis, and laser-induced fluorescence detection provides a sensitivity in the low picomolar range and a highly linear fluorescence response over 4 orders of magnitude (IgE concentration ranging from 2.4 to 2400 ng/mL). After validation with a reference material, the method has been successfully applied to the quantification of total IgEs in patient sera. The results compared well with classical ImmunoCap data.     

DNA transport in hierarchically-structured colloidal-nanoparticle porous-wall nanochannels

We report a simple approach to the formation of 3D colloidal nanoparticle structures incorporating enclosed mesoscopic structures through a simple process of spin-coating-driven directed self-assembly onto lithographically defined polymer templates. Removal of the buried polymer patterns by high temperature calcination results in the formation of hierarchically enclosed channels, continuous networks, isolated cavities, and multilayered structures with high stability and environmental resistance. These channels are used to investigate the transport of DNA molecules in constrained geometries.     

Current rectification by mediating electroactive polymers

In this work we briefly review the theoretical basis for the electrochemical rectification in mediated redox reactions at redox polymer modified electrodes. Electrochemical rectification may have two distinct origins. It is either caused by a slow kinetics of the reaction between the external redox couple and the mediator or it is originated by a slow electronic transport within the film under an unfavorable thermodynamic condition. We show experimental results for the redox mediation reaction of poly(o-aminophenol) (POAP) on the Fe^2+/3+ and on the Fe(CN)₆^3−/4− redox couples in solution that prove the proposed mechanisms of electrochemical rectification.     

Isolation,identification and development of culture medium in the production of Chlorella vulgaris

Microalgae have gained importance as a potential component of conventional food. The aim of the present study was to study the behaviour of the microalga Chlorella vulgaris in relation to the different carbon and nitrogen sources and to improve a culture medium in terms of glucose, urea, manganese chloride and sodium nitrate concentrations. In the investigation of the best source of carbon and nitrogen, it was observed that 1.14 mg L^?1 of glucose and 8.32 mg L^?1 of urea stood out with the production of 0.823 g L^?1 of dry biomass and yield of 52 mg L^?1 day^?1. The best growth rate and specific yield were achieved at the central points for all salts.     

An improved gravimetric method applied to co-processing of polyethylene terephtalate and petroleum blend using HY zeolite as a catalyst

The co-processing of petroleum and polyethylene terephthalate (PET) was carried out in the presence and absence of a catalyst in an open vessel batch reactor at temperatures of 200, 300, 400, and 500 °C, which corresponds to temperatures of distillation and cracking. The catalyst used was the acidic HY zeolite, which is widely used in petroleum refining. The catalytic co-processing was carried out with the PET–oil charge, at a mass ratio of 1:1, containing 10% of HY zeolite. The conversion degree was measured by knowing the initial sample mass and amount of degraded material for each temperature and reaction time, using an improved gravimetric method consisting of a precision balance and an oven with a heating rate controller. The conversion values obtained were compared for petroleum and PET samples with and without the zeolite catalyst. At temperatures of 200 and 300 °C, the PET showed low conversions, about 5–10%. However, for the catalytic co-processing of PET–oil/HY at these same temperatures, an increase in conversion to about 25–30% was observed. At temperatures of 400 and 500 °C, conversions above 90% were obtained for the two samples, with a subsequent reduction in the activation energy, from 76 kJ mol^?1 (PET) to 56 kJ mol^?1 (PET–oil/HY). The decrease in the activation energy proved the efficiency of the HY zeolite and the synergistic effect when PET was blended to the oil for the catalytic co-processing, proving to be a viable alternative for the chemical recycling of PET in the petroleum industry.     

Electron transport through supported biomembranes at the nanoscale by conductive atomic force microscopy

We present a reliable methodology to perform electron transport measurements at the nanoscale on supported biomembranes by conductive atomic force microscopy (C-AFM). It allows measurement of both (a) non-destructive conductive maps and (b) force controlled current-voltage characteristics in wide voltage bias range in a reproducible way. Tests experiments were performed on purple membrane monolayers, a two-dimensional (2D) crystal lattice of the transmembrane protein bacteriorhodopsin. Non-destructive conductive images show uniform conductivity of the membrane with isolated nanometric conduction defects. Current-voltage characteristics under different compression conditions show non-resonant tunneling electron transport properties, with two different conduction regimes as a function of the applied bias, in excellent agreement with theoretical predictions. This methodology opens the possibility for a detailed study of electron transport properties of supported biological membranes, and of soft materials in general.