Inorganofunctionalization of Ti(IV) and Zr(IV) on the MCM-41 Surface and its Interaction with a Mixed Valence Complex to use as Isoniazid Sensing

Journal of Inorganic and Organometallic Polymers and Materials - In this work, it describes the preparation of Titanium and Zirconium functionalized MCM-41 and subsequent chemical modification with...     

The Olsen P method as an agronomic and environmental test for predicting phosphate release from acid soils

The role of soil phosphorus (P) in the eutrophication of fresh water systems is well established. It is crucial therefore to assess the potential loss of P from soil in the various scenarios where soil can come into contact with water. To date, such assessment has often been based on soil P tests that are used for agronomic purposes (e.g. fertilizer recommendations). The purpose of this work was to examine the usefulness of one such test (viz. the Olsen test, which is based on extraction with bicarbonate) for predicting not only the amount of soil P available to plants, but also that which can be desorbed to water in a group of 32 Portuguese soils, of which 29 were acid and 3 calcareous. To this end, we (i) assessed the total amount of phytoavailable P in soil by successively pot-cropping Chinese cabbage, buckwheat and rye; and (ii) measured the amount of phosphate-P desorbed to a dilute electrolyte mimicking fresh water over periods of up to 218 days at soil:solution ratios of 1:100, 1:1000 and 1:10000. Total phytoavailable P and Olsen P were found to bear a quadratic relationship, with Olsen’s extractant underestimating the content in phytoavailable P of soils with high Olsen P contents relatively to soils with low contents. The “change point” at which phytoavailable P began to increase rapidly per unit change in Olsen P was 53 mg Olsen P kg⁻¹ soil. For the acid soils, a significant quadratic relationship was found between the amount of P desorbed to water and Olsen P at the three soil:solution ratios studied. However, these relationships became less significant when only the soils with an Olsen P value of less than 50 mg kg⁻¹ were considered. For the acid soils, the change point at which P input to water began to increase rapidly per unit change in Olsen P was 20, 61 and 57 mg kg⁻¹ at the 1:100, 1:1000 and 1:10000 ratio, respectively. At comparable Olsen P values, the calcareous soils released more phosphate to water than the acid soils. On the basis of our results, we suggest the following environmental threshold values for Olsen P in acid soils: 20 mg kg⁻¹ for P desorption scenarios where the soil:solution ratio is high (e.g. drainage water) and 50 mg kg⁻¹ for desorption scenarios where the soil:solution ratio is low (e.g., runoff, water in reservoirs). Both values are higher than the agronomic threshold above which plants are well supplied with P.     

Edge‐Node Deployed Routing Strategies for Load Balancing in Optical Burst Switched Networks

Optical burst switching is a promising switching paradigm for the next IP‐over‐optical network backbones. However, its burst loss performance is greatly affected by burst contention. Several methods have been proposed to address this problem, some of them requiring the network to be flooded by frequent state dissemination signaling messages. In this work, we present a traffic engineering approach for path selection with the objective of minimizing contention using only topological information. The main idea is to balance the traffic across the network to reduce congestion without incurring link state dissemination protocol penalties. We propose and evaluate two path selection strategies that clearly outperform shortest path routing. The proposed path selection strategies can be used in combination with other contention resolution methods to achieve higher levels of performance and support the network reaching stability when it is pushed under stringent working conditions. Results show that the network connectivity is an important parameter to consider.     

Pre-planned optical burst switched routing strategies considering the streamline effect

Optical burst switching is a promising paradigm for the next IP over optical network backbones. However, due to its bufferless nature, it can be highly affected by burst contention. Several methods have been proposed to address this problem, most of them without considering a phenomenon unique to optical burst switched networks called streamline effect. Most of the reported studies also assume the existence of total wavelength conversion capacity on all nodes, presently a very expensive and somewhat unrealistic configuration, and additionally, the contention resolution schemes adopted increase in the complexity of the core nodes, hampering scalability. In this study, we present a traffic engineering approach for path selection with the objective of minimizing the contention considering the streamline effect and using only topological information. The main idea is to balance the traffic across the network in order to prevent congestion while keeping simple the architecture of the core nodes and without incurring into link state dissemination penalties. We propose and evaluate the path selection strategies in both networks with full wavelength conversion capability and networks with imposed wavelength continuity constraint. Results show that our strategies can outperform the traditionally used shortest path routing.     

Adsorption and electropolymerization of toluidine blue on the nanostructured octakis(hydridodimethylsiloxy)octasilsesquioxane surface

Toluidine blue O (TBO) was adsorbed on the octakis(hydridodimethylsiloxy)octasilsesquioxane (Q₈M₈^H) surface. The characterization of the precursor (Q₈M₈^H) and resulting materials obtained by the reaction of Q₈M₈^H and toluidine blue (CTBO) were defined using Fourier transform infrared spectra, nuclear magnetic resonance solid-state ¹³C and Si²⁹ magic angle spinning. The electrochemical polymerization in a glassy carbon electrode was verified by means of a film silsesquioxane formation (FCTBO) using cyclic voltammetry in a potential range of −0.5 to 1.3 V (vs. saturated calomel electrode (SCE)) in a Britton Robinson (B-R) buffer solution (pH 2.0). The cyclic voltammogram of the film exhibits two redox couples with a formal potential of −0.15 and −0.02 V (B-R buffer pH 5). The formal potential shifts linearly in the cathodic direction by increasing the pH solution with a slope of 71 and 57 mV per unit for the first and second couple, respectively. The film was electrochemically very stable.     

Polycyclic Aromatic Hydrocarbons from Candiota (South Brazilian) Coal Extracts

The bitumen composition of Candiota coal (south Brazil) was investigated. Coal bitumen was produced by Soxhlet extraction using toluene. Two chromatographic techniques were tested for bitumen fractionation: adsorption liquid chromatography on silica (ALCS) and adsorption liquid chromatography on alumina (ALCA). Results were compared in terms of the quality and quantity of hydrocarbons isolated. Several linear saturated hydrocarbons were found in the range of 14 to 33 carbons. Pyrene, chrysene, and other polycyclic hydrocarbons with recognized mutagenic and carcinogenic properties were found in the aromatic fractions. Chromatographic methodology using alumina shows better results in the fractionation of bitumen.     

Multivariate statistical analysis of diamondoid and biomarker data from Brazilian basin oil samples

Diamondoids are compounds commonly found in oils. Highly stable, they are more resistant to thermal and biological destruction than other hydrocarbons. Diamondoid-derived parameters have been used to assess the degree of thermal evolution and the extent of secondary cracking of light oils and condensates and in the identification of mixtures of oils from distinct migration pulses. Twenty-one samples of oils from five sedimentary basins of Brazilian continental margin were selected and studied on diamondoids and biomarkers. The oil samples were analyzed by gas chromatography coupled to mass spectrometry and principal components analysis (PCA) aiming to correlate biomarker and diamondoid parameters. Diamondoid and biomarker ratios analyzed by PCA led to a more accurate assessment of the maturity of the oils. The combination of diamondoid data with biomarker parameters also allowed to rank the oils from one of the five basins (JX basin) as the most mature oils, while oils from another basin (JE basin) were classified as mixtures formed from different pulses of migration.