Analysis of the performance of polysaccharide membranes in aqueous media as a tool to assist wound‐dressing selection

The behavior of hydrophilic matrixes in the presence of aqueous media plays a pivotal role in the selection of materials that come into contact with body fluids. Because polysaccharides have proven benefits in the treatment of skin lesions, the performance of membranes produced with chitosan combined with alginate [chitosan–alginate (Ch–A)], xanthan [chitosan–xanthan (Ch–X)], or guar gum [chitosan–guar gum (Ch–G)] after exposure to different aqueous solutions and humidity levels was analyzed with the aim of directing their applications as dressings in wounds with different exudate productions. The Ch–X membranes presented a high fluid‐uptake capacity and water‐vapor transmission rate (WVTR); this was attributed to ramifications in the xanthan structure, and the membranes were then recommended for moderately to highly exuding wounds. The Ch–G membranes showed a dense structure and presented low fluid‐uptake capacity; they were more appropriate for low‐exuding wounds or wounds in the advanced stage of cicatrization. Both the Ch–A and Ch–G membranes presented adequate mechanical properties in a wide range of relative humidity conditions and could be considered suitable for use in all body parts. However, as the Ch–A formulation showed limited WVTR, its use should be restrictedly to, at most, moderately exuding wounds. In all cases, the assessment of the wound type by a professional would be required to define the final dressing formulation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45386.     

An adaptive location management scheme for mobile broadband cellular systems

This paper presents an adaptive location management strategy that considers both location updating and paging by evaluating realistic mobility patterns. It proposes the design of an adaptive macro-location area based on multi-registration adapted to the terminals’ trajectory to reduce location updates. The solution includes an estimation of residence probabilities in the areas of the multi-registered list. This facilitates the design of a sequential paging scheme that reduces the average paging cost. Results show the capability of the solution to adapt to mobility patterns and traffic conditions in the network to minimize the overall location cost. Furthermore, the multi-registration approach and the reduced complexity in both network infrastructure and mobile terminals make the solution suitable for new packet-based broadband cellular systems.     

Review of Wood Drying Research in Brazil: 1984-2004

In Brazil, research on wood drying has been more focused on applied aspects than on fundamentals ones, and results have been published almost exclusively in Brazilian journals. The study of lumber deformation under aggressive drying conditions resulted in methods to group species and to define kiln schedules. Relationship between moisture content and electrical resistivity was used to improve quality control of dried lumber as well automatic control of the kiln drying process. Conventional kiln drying is the most common method for industrial drying, but seasoning and solar drying were also studied. The biggest research effort was directed to improve the drying of eucalypt lumber.     

A study of the aroma of fried bacon and fried pork loin

Aroma compounds in the headspace volatiles of fried bacon and fried pork loin were identified. The concentrations of volatiles in bacon were much lower than those in pork loin, except for nitrogen compounds. It is likely that these differences were caused by the presence of nitrite in bacon. Characteristic aromas for fried bacon, described variously as bacon‐, fried meat‐, roast meat‐ and cooked meat‐like, were found through olfactory testing. These aromas were not present in the pork loin samples. Compounds such as pyrazines, pyridines and furans are thought to be responsible for these meaty aromas. Copyright © 2004 Society of Chemical Industry     

Synergistic Interaction of Dyes and Semiconductor Quantum Dots for Advanced Cascade Cosensitized Solar Cells

A new procedure for the cosensitization with quantum dots (QDs) and dyes for sensitized solar cells is reported here. Cascade cosensitization of TiO₂ electrodes is obtained by the sensitization with CdS QDs and zinc phthalocyanines (ZnPcs), in which ZnPcs containing a sulfur atom are specially designed to produce a cascade injection by direct attachment to QDs. This strategy causes a double synergetic interaction. This is the differentiating point of cascade cosensitization in comparison with other approaches in which dyes with conventional functionalization are anchored to TiO₂ electrodes. Cosensitization produces a panchromatic response from the visible to near‐IR region already observed with other sensitization strategies. However, cascade cosensitization produces in addition a synergistic interaction between QDs and dye, that it is not merely limited to the complementary light absorption, but dye enhances the efficiency of QD sensitization acting as a passivating agent. The cascade cosensitization concept is demonstrated with using [Co(phen)₃]^3+/2+ redox electrolyte. The TiO₂/CdS QD‐ZnPc/[Co(phen)₃]^3+/2+ sensitized solar cell shows a large improvement of short‐circuit photocurrent and open‐circuit voltage in comparison with samples just sensitized with QDs. The advent of such cosensitized QD‐ZnPc solar cells paves the way to extend the absorbance region of the promising QD‐based solar cells and the development of a new family of molecules designed for this purpose.     

Value of the exponential current-time perturbation for achieving stationary polarisation curves at planar and spherical electrodes of any size

Stationary current-potential (I-E) polarisation curves (SPCs) are of interest in electrochemistry, because the extraction of thermodynamic and kinetic information from such curves is easy. In order to obtain the SPCs under pure diffusion transport conditions, experiments are usually performed using spherical electrodes, at which the SPCs are rapidly attained. A purely diffusional steady state cannot be achieved at planar electrodes. However, the theoretical analysis presented in this work reveals that in the case of chronopotentiometry with exponential current-time perturbation, the Nernst diffusion layer reaches a constant thickness, for a simple charge transfer reaction. Consequently, the I-E curves obtained under these conditions are SPCs, both for the spherical and planar electrodes. This theoretical prediction is confirmed experimentally for the reversible oxidation of ferrocene in acetonitrile solution of lithium perchlorate, and irreversible reduction of hexaamminecobalt (III) nitrate in aqueous solution of sodium perchlorate.     

Characterisation of tequila according to their major volatile composition using multilayer perceptron neural networks

Differentiation of silver, gold, aged and extra-aged tequila using 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol and furan derivatives like 5-(hydroxymethyl)-2-furaldehyde and 2-furaldehyde has been carried out. The content of 1-propanol, ethyl acetate, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-methyl-1-butanol was determined by means of head space solid phase microextraction gas chromatography mass-spectrometry. 5-(Hydroxymethyl)-2-furaldehyde and 2-furaldehyde were determined by high performance liquid chromatography with diode array detection. Kruskal–Wallis test was used to highlight significant differences between types of tequila. Principal component analysis was applied as visualisation technique. Linear discriminant analysis and multilayer perceptron artificial neural networks were used to construct classification models. The best classification performance was obtained when multilayer perceptron model was applied.     

Determination of naturally occurring progestogens in bovine milk as their oxime derivatives using high performance liquid chromatography–electrospray ionization–tandem mass spectrometry

BACKGROUND: Hormones and hormone‐like substances which are present in the environment have been repeatedly accused of being the cause of most endocrine disruption. However, the possible role of endogenous hormones in food of animal origin deserves to be discussed as well. The relation between steroid hormones and several human health problems has been previously reported, such as prostate and breast cancer, perturbation of human reproduction and endocrine disruption on humans and wildlife. This research is particularly concerned with cow's milk, which contains a considerable amount of sex hormones. RESULTS: A liquid chromatography–tandem mass spectrometry method has been developed for the simultaneous detection and quantification of four naturally occurring steroid hormones in commercial bovine milk (pregnenolone (P₅), progesterone (P₄), 17‐hydroxypregnenolone (17‐OHP₅), 17‐hydroxyprogesterone (P₄)). Oxime derivatives of steroids were analyzed in positive ionization and multiple reaction monitoring mode. Methodology has been validated according to Decision 2002/657/EC criteria. CONCLUSION: This method has been successfully used in real samples. It is fast and easy‐handling and provides a useful tool for the assessment of progestogens in bovine milk. Copyright © 2010 Society of Chemical Industry