Incompressible surfaces in handlebodies and boundary reducible 3-manifolds

We study the existence of incompressible embeddings of surfaces into the genus two handlebody. We show that for every compact surface with boundary, orientable or not, there is an incompressible embedding of the surface into the genus two handlebody. In the orientable case the embedding can be either separating or non-separating. We also consider the case in which the genus two handlebody is replaced by an orientable 3-manifold with a compressible boundary component of genus greater than or equal to two.     

Cork-based activated carbons as supported adsorbent materials for trace level analysis of ibuprofen and clofibric acid in environmental and biological matrices

In this contribution, powdered activated carbons (ACs) from cork waste were supported for bar adsorptive micro-extraction (BAμE), as novel adsorbent phases for the analysis of polar compounds. By combining this approach with liquid desorption followed by high performance liquid chromatography with diode array detection (BAμE(AC)-LD/HPLC-DAD), good analytical performance was achieved using clofibric acid (CLOF) and ibuprofen (IBU) model compounds in environmental and biological matrices. Assays performed on 30 mL water samples spiked at the 25.0 μg L(-1) level yielded recoveries around 80% for CLOF and 95% for IBU, under optimized experimental conditions. The ACs textural and surface chemistry properties were correlated with the results obtained. The analytical performance showed good precision (<15%), suitable detection limits (0.24 and 0.78 μg L(-1) for CLOF and IBU, respectively) and good linear dynamic ranges (r(2)>0.9922) from 1.0 to 600.0 μg L(-1). By using the standard addition methodology, the application of the present approach to environmental water and urine matrices allowed remarkable performance at the trace level. The proposed methodology proved to be a viable alternative for acidic pharmaceuticals analysis, showing to be easy to implement, reliable, sensitive and requiring low sample volume to monitor these priority compounds in environmental and biological matrices.     

Casbane diterpene as a promising natural antimicrobial agent against biofilm-associated infections

Croton nepetaefolius is a native plant from northeastern Brazil that belongs to the Euphorbiaceae family. The biological action of this plant has been extensively explored, being the secondary metabolites responsible for its properties alkaloids, diterpenes, and triterpenes. This study aimed to evaluate the ability of casbane diterpene (CD), isolated from the ethanolic extract of C. nepetaefolius, to inhibit microbial growth and biofilm formation of several clinical relevant species (bacteria and yeasts). It was found that CD possessed biocidal and biostatic activity against the majority of the species screened, with minimal active concentrations ranging between 125 and 500 μg/mL. In addition, it was observed that biofilm formation was inhibited even when the planktonic growth was not significantly affected. In conclusion, CD showed potential to be a natural tool for the treatment of diseases caused by different infectious microorganisms.     

Lignin biodegradation by the ascomyceteChrysonilia sitophila

The lignin biodegradation process has an important role in the carbon cycle of the biosphere. The study of this natural process has developed mainly with the use of basidiomycetes in laboratory investigations. This has been a logical approach since most of the microorganisms involved in lignocellulosic degradation belong to this class of fungi. However, other microorganisms such as ascomycetes and also some bacteria, are involved in the lignin decaying process. This work focuses on lignin biodegradation by a microorganism belonging to the ascomycete class,Chrysonilia sitophila. Lignin peroxidase production and characterization, mechanisms of lignin degradation (lignin model compounds and lignin in wood matrix) and biosynthesis of veratryl alcohol are outstanding. Applications of C.sitophila for effluent treatment, wood biodegradation and single-cell protein production are also discussed.     

Radioresistance studies in Methylobacterium spp.

Methylobacterium extorquen was isolated and was found as one of the most resistant microorganisms in the original bioburden of ophthalmic cotton dressings to be submitted to γ radiation sterilization. Radiation survival curves were simultaneously performed in phosphate buffer and in test-pieces on two isolates, one obtained before irradiation (wild strain) and the other after irradiation at 20 kGy (rad strain), as well as on three type strains of Methylobacterium spp. (M. extorquens^T, M. radiotolerans^T and M. fujisawaense^T). The radiation resistance was compared using D_values. To analyze the effect of non linearity on radioresistance other measures were applied, such as intercept point, fraction of surviving cells at a selected dose and area. The ranking of strains with these approaches showed to be different, pointing out the need of an integrated measure of radioresistance. Therefore, an index of relative survival (IRS) is proposed.     

Adsorption of silanes bearing nitrogenated Lewis bases on SiO2/Si (100) model surfaces

The present paper describes the one-pot procedure for the formation of self-assembled thin films of two silanes on the model oxidized silicon wafer, SiO2/Si. SiO2/Si is a model system for other surfaces, such as glass, quartz, aerosol, and silica gel. MALDI-TOF MS with and without a matrix, XPS, and AFM have confirmed the formation of self-assembled thin films of both 3-imidazolylpropyltrimethoxysilane (3-IPTS) and 4-(N-propyltriethoxysilane-imino)pyridine (4-PTSIP) on the SiO2/Si surface after 30 min. Longer adsorption times lead to the deposition of nonreacted 3-IPTS precursors and the formation of agglomerates on the 3-IPTS monolayer. The formation of 4-PTSIP self-assembled layers on SiO2/Si is also demonstrated. The present results for the flat SiO2/Si surface can lead to a better understanding of the formation of a stationary phase for affinity chromatography as well as transition-metal-supported catalysts on silica and their relationship with surface roughness and ordering. The 3-IPTS and 4-PTSIP modified SiO2/Si wafers can also be envisaged as possible built-on-silicon thin-layer chromatography (TLC) extraction devices for metal determination or N-heterocycle analytes, such as histidine and histamine, with "on-spot" MALDI-TOF MS detection.     

Performance parameters of a whole body counter

Techniques for the assessment of internally incorporated radionuclides are essential for monitoring potentially exposed workers to radiation as well as for the preparedness of response in the case of Radiological Emergencies. The Whole Body Counter at Instituto Tecnológico e Nuclear (ITN), Portugal, provides a direct way of measuring the activity of internally incorporated radionuclides in possibly contaminated persons. This equipment is calibrated in energy and efficiency, with a calibration source, and is able to detect and quantify several radionuclides with gamma emissions between 60 and 1900 keV. Also, the Minimum Detectable Activity values for several nuclides of interest were determined, since these values are an indication of the sensitivity of the detection system. Finally, in order to assure reliable measurements, a quality assurance routine has been implemented, consisting of routinely monitoring several parameters of chosen radionuclides with gamma emission energies lying in the energy range of interest, and also for the background. The equipment is now fully operational and a set of routine measurements for the monitoring of exposed personnel, working in different areas of activity, is currently being prepared.     

Knot exteriors with all possible meridional essential surfaces

We show the existence of infinitely many knots where each exterior contains meridional essential surfaces of independently unbounded genus and number of boundary components. In particular, we construct examples of knot exteriors each of which has all possible compact orientable surfaces embedded as meridional essential surfaces. From these results, we also prove the existence of a hyperbolic knot exterior, not necessarily of a knot in the 3-sphere, for which there are meridional essential surfaces of simultaneously unbounded genus and number of boundary components.     

Complex and superlattice stacking faults in D019 Co3W

Planar defects present in annealed D0₁₉?Co₃W crystals have been investigated by conventional transmission electron microscopy. Although a predominance of superlattice stacking faults was observed, five antiphase boundaries and four complex stacking faults were identified. All planar defects were observed in locked configurations or ended at grain boundaries. A comparison of relative defect energies has been carried out with a geometrical model based on pairwise interaction energies. The results suggest that the relative number of defects is not directly related to their expected energy, but rather has origin in locked configurations adopted during crystal growth and annealing.