Finite element simulation based‐on atomic force microscopy and nanoindentation for spruce wood microstructure analysis

Spruce wood (picea abis) has been widely used as structural element, from buildings to musical instruments, due to its outstanding mechanical performances. The main stem transverse section exhibits growth rings formed by periodic fringes patterns, which are constituted by lamellae‐tracheid arrangements. In order to improve the understanding of each wood microstructure role, the morphology and crystallinity of earlywood and latewood fibers were examined mainly using scanning electron microscopy, atomic force microscopy, and X‐ray difracction. Moreover, measurements of effective elastic modulus and hardness were obtained by nanoindentation tests using a Berkovich indenter in order to confirmed increase in compactness of the wood microstructures. The results indicate that variations in mechanical properties values can be associated with well defined microstructural performances for each characteristic fiber type, where those that belong to latewood fiber showed the most improved behaviors. A finite element simulation of a lamellar‐tracheids arrangement was carried out in order to clarify its stiffness and elastic deformation capabilities, as relevant factors contributing to the successful adaptation of picea abis colonies to harsh conditions habitats as well as for its construction applications of string instruments.     

The PQQ-alcohol dehydrogenase of Gluconacetobacter diazotrophicus

The oxidation of ethanol to acetic acid is the most characteristic process in acetic acid bacteria.Gluconacetobacter diazotrophicus is rather unique among the acetic acid bacteria as it carries out nitrogen fixation and is a true endophyte, originally isolated from sugar cane. Aside its peculiar life style, Ga. diazotrophicus, possesses a constitutive membrane-bound oxidase system for ethanol. The Alcohol dehydrogenase complex (ADH) of Ga. diazotrophicus was purified to homogeneity from the membrane fraction. It-exhibited two subunits with molecular masses of 71.4 kDa and 43.5 kDa. A positive peroxidase reaction confirmed the presence of cytochrome c in both subunits. Pyrroloquinoline quinone (PQQ) of ADH was identified by UV-visible light and fluorescence spectroscopy. The enzyme was purified in its full reduced state; potassium ferricyanide induced its oxidation. Ethanol or acetaldehyde restored the full reduced state. The enzyme showed an isoelectric point (pI) of 6.1 and its optimal pH was 6.0. Both ethanol and acetaldehyde were oxidized at almost the same rate, thus suggesting that the ADH complex of Ga. diazotrophicus could be kinetically competent to catalyze, at least in vitro, the double oxidation of ethanol to acetic acid.     

Development of Biarylalkyl Carboxylic Acid Amides with Improved Anti-schistosomal Activity

The parasitic disease schistosomiasis is the cause of more than 200 000 human deaths per year. Although the disease is treatable, there is one major shortcoming: praziquantel has been the only drug used to combat these parasites since 1977. The risk of the emergence of resistant schistosomes is known to be increasing, as a reduced sensitivity of these parasites toward praziquantel has been observed. We developed a new class of substances, which are derived from inhibitors of human aldose reductase, and which showed promising activity against Schistosoma mansoni couples in vitro. Further optimisation of the compounds led to an increase in anti-schistosomal activity with observed phenotypes such as reduced egg production, vitality, and motility as well as tegumental damage and gut dilatation. Here, we performed structure–activity relationship studies on the carboxylic acid moiety of biarylalkyl carboxylic acids. Out of 82 carboxylic acid amides, we identified 10 compounds that are active against S. mansoni at 25 μm . The best five compounds showed an anti-schistosomal activity up to 10 μm and induced severe phenotypes. Cytotoxicity tests in human cell lines showed that two derivatives had no cytotoxicity at 50 or 100 μm . These compounds are promising candidates for further optimisation toward the new anti-schistosomal agents.     

Carbon,nitrogen and phosphorus recovery from liquid swine wastes: a review

Due to the pollution characteristics of the wastewater generated in piggeries, these waste streams have to be treated before discharging into the environment. These wastes have a high content of organic matter, nitrogen and phosphorus that can be converted or recovered into valuable products. The valuation of swine waste by anaerobic digestion has already been assessed, but no systematic review on the technologies used for recovering nutrients from this waste has been reported to date. Therefore, the present work has the goal of presenting the most studied technologies to different scales of recovery of carbon (i.e. organic matter), nitrogen and phosphorus from swine waste. The main characteristics and parameters of the processes involved in these technologies (mainly air stripping, membrane, enhance biological phosphorus removal and struvite formation) are also highlighted, pointing out its advantages and disadvantages and posing some final feasibility considerations on the subject addressed. Experiments reported in the literature proved that technologies used for nutrient recovery from swine waste are mostly applied to the effluents previously treated by anaerobic digestion as a primary treatment, and greater effort is required for the future implementation of these technologies in large scale. © 2020 Society of Chemical Industry     

Studies on ultrasonic scattering from quasi-periodic structures

This study extends the work done on nonuniform phase statistics by including additional results based on quasi-periodic scattering. Three parameters are used to predict the presence of regular structure within the region of interest. The signal-to-noise ratio of phase and the chi (2) statistic resulting from conducting a goodness of fit test are two parameters used to verify whether the phase signal followed a uniform distribution. A third parameter, the power spectral density (PSD), was studied and its ability to provide information on the level of periodicity present was analyzed. Computer simulations and experiments on tissue mimicking phantoms were carried out, the results of which indicate that the parameters introduced in this paper have good potential in providing a better understanding of scattering from a collection of quasi-periodic scatterers.