A multiorganism based method for Bayesian gene network estimation

The primary goal of this article is to infer genetic interactions based on gene expression data. A new method for multiorganism Bayesian gene network estimation is presented based on multitask learning. When the input datasets are sparse, as is the case in microarray gene expression data, it becomes difficult to separate random correlations from true correlations that would lead to actual edges when modeling the gene interactions as a Bayesian network. Multitask learning takes advantage of the similarity between related tasks, in order to construct a more accurate model of the underlying relationships represented by the Bayesian networks. The proposed method is tested on synthetic data to illustrate its validity. Then it is iteratively applied on real gene expression data to learn the genetic regulatory networks of two organisms with homologous genes.     

A study on the positive ellipticity in the circular dichroism of ribonuclease A

The small positive elliplicity near 239 nm in the CD spectrum of RNase has been investigated as a function of pH. Theoretical calculations using CD parameters representing buried or exposed tyrosine residues have been carried out. A comparison of the theoretical calculations with experimental data suggests that the changes in the band's intensity, as a function of pH, arise mainly from electronic transitions associated with the tyrosine residues. The buried tyrosine residues are the major contributors to the ellipticity in this region at neutral pH. At higher pH contributions from exposed residurs are also observed.     

Surface energetics to assess biomass attachment onto immobilized metal-ion chromatography adsorbents in expanded beds

Cell-to-support interaction and cell-to-cell agglomeration phenomena have been studied in a model system composed of intact yeast cells and Chelating-Streamline™ adsorbents. Biomass components and beaded adsorbents were mainly characterized by contact angle determinations with three diagnostic liquids. Complementarily, zeta potential measurements were performed. These experimental values were employed to calculate free energy of interaction versus distance profiles in aqueous media. The effect of immobilized metal-ion type and buffer pH on the interaction energy was evaluated. Calculations indicated that moderate interaction between cell particles and adsorbent beads can develop due to the presence of Cu²⁺ ions onto the solid phase. The strength of interaction increased with buffer pH, within the range 6.0 to 8.3 e.g. secondary energy pockets increased from |15| to |60| kT. Cell-to-cell secondary energy minimum was ≥ |14| kT showing low-to-moderate tendencies to aggregate, particularly at pH ≥ 8. Extended DLVO predictions were generally confirmed by biomass deposition experiments. However, an exception was found when working with immobilized Cu²⁺ at pH 8 since yeast cells were able to sequestrate such immobilized ions. Therefore, lower-than-expected values for the depositions coefficient (α) were observed. Understanding biomass attachment onto Chelating supports can help in better design and operate expanded bed adsorption of bioproducts.     

Chromium Phytoaccumulation from Solution by Selected Hydrophytes

There is increasing interest in the role of wetland plants in the aquatic phytoremediation of toxic metals. In this experiment, we evaluate the Cr removal capacity of four hydrophyte species (Nasturtium officinale L., Veronica beccabunga L., Mentha longifolia L., R.Br., Cardamine uliginosa L.) under varying nutritional conditions (full-strength and half-strength solution cultures), and over a range of Cr concentration (0, 2, 4, 6, and 8 mg L^-1). The results indicate that Cr accumulation is affected by both initial Cr concentration and strength of the nutrient solution. Phytoaccumulation increased with initial Cr concentration and plants grown in the full-strength solution accumulated more Cr at the higher initial solution concentration. Cr was predominantly accumulated in the roots, with minimal shoot translocation, which limits the hazard of Cr entering the food chain through ingestion by animals. Accumulation was large and reached up to 6700 mg Cr Kg^-1 in the roots of Veronica beccabunga.     

High-performance thin-layer chromatographic determination of 5-methoxypsoralen in serum from patients

A simple and rapid high-performance thin-layer chromatographic (HPTLC) determination of 5-methoxypsoralen in serum is necessary for the therapeutic survey of patients treated with Puvatherapy (psoralen+UV A). The assay for this biological fluid involves an extraction with heptane-dichloromethane (4:1, v/v). The analytical method is linear from 50 to 250 ng/ml. This assay range is adequate for analysing human serum, as it corresponds to psoralen concentrations measured in serum from patients treated with psoralen and UV A against psoriasis and vitiligo. The limit of detection is 15 ng/ml. The coefficient of variation was less than 7%.     

Interferometric optical fiber sensor for optoacoustic endomicroscopy

Optical fiber sensors can offer robust and miniaturized detection of wideband ultrasound, yielding high sensitivity and immunity to electromagnetic interference. However, the lack of cost-effective manufacturing methods prevents the disseminated use of these sensors in biomedical applications. In this study, we developed and optimized a simple method to create optical cavities with high-quality mirrors for acoustic sensing based on micro-manipulation of UV-curable optical adhesives and electroless chemical silver deposition. This approach enables the manufacturing of ultrasound sensors based on Fabry-Pérot interferometers on optical fiber tips with minimal production costs. Characterization and high-resolution optoacoustic imaging experiments show that the manufacturing process yielded a fiber sensor with a small NEP () over a broad detection bandwidth (25 MHz), generally outperforming conventional piezoelectric based transducers. We discuss how the new manufacturing process leads to a high-performance acoustic detector that, due to low cost, can be used as a disposable sensor.     

Current and emerging environmentally-friendly systems for fouling control in the marine environment

Following the ban in 2003 on the use of tributyl-tin compounds in antifouling coatings, the search for an environmentally-friendly alternative has accelerated. Biocidal TBT alternatives, such as diuron and Irgarol 1051®,¹ have proved to be environmentally damaging to marine organisms. The issue regarding the use of biocides is that concerning the half-life of the compounds which allow a perpetuation of the toxic effects into the marine food chain, and initiate changes in the early stages of the organisms' life-cycle. In addition, the break-down of biocides can result in metabolites with greater toxicity and longevity than the parent compound.