Phylogeny of snake trypanosomes inferred by SSU rDNA sequences, their possible transmission by phlebotomines, and taxonomic appraisal by molecular, cross-infection and morphological analysis

Blood examination by microhaematocrit and haemoculture of 459 snakes belonging to 37 species revealed 24% trypanosome prevalence in species of Viperidae (Crotalus durissus and Bothrops jararaca) and Colubridae (Pseudoboa nigra). Trypanosome cultures from C. durissus and P. nigra were behaviourally and morphologically indistinguishable. In addition, the growth and morphological features of a trypanosome from the sand fly Viannaniyia tuberculata were similar to those of snake isolates. Cross-infection experiments revealed a lack of host restriction, as snakes of 3 species were infected with the trypanosome from C. durissus. Phylogeny based on ribosomal sequences revealed that snake trypanosomes clustered together with the sand fly trypanosome, forming a new phylogenetic lineage within Trypanosoma closest to a clade of lizard trypanosomes transmitted by sand flies dagger. The clade of trypanosomes from snakes and lizards suggests an association between the evolutionary histories of these trypanosomes and their squamate hosts. Moreover, data strongly indicated that these trypanosomes are transmitted by sand flies. The flaws of the current taxonomy of snake trypanosomes are discussed, and the need for molecular parameters to be adopted is emphasized. To our knowledge, this is the first molecular phylogenetic study of snake trypanosomes.

Phylogenetic, morphological and behavioural analyses support host switching of Trypanosoma (Herpetosoma) lewisi from domestic rats to primates

We characterized four Brazilian trypanosomes isolated from domestic rats and three from captive nonhuman primates that were morphologically similar to T. lewisi, a considered non-pathogenic species restricted to rodents and transmitted by fleas, despite its potential pathogenicity for infants. These isolates were identified as T. lewisi by barcoding using V7V8 SSU rDNA sequences. In inferred phylogenetic trees, all isolates clustered tightly with reference T. lewisi and T. lewisi-like trypanosomes from Europe, Asia and Africa and despite their high sequence conservation formed a homogeneous clade separate from other species of the subgenus T. (Herpetosoma). With the aim of clearly resolving the relationships between the Brazilian isolates from domestic rats and primates, we compared sequences from more polymorphic ITS rDNA. Results corroborated that isolates from Brazilian rats and monkeys were indeed of the same species and quite close to T. lewisi isolates of humans and rats from different geographical regions. Morphology of the monkey isolates and their behaviour in culture and in experimentally infected rats were also compatible with T. lewisi. However, infection with T. lewisi is rare among monkeys. We have examined more than 200 free-ranging and 160 captive monkeys and found only three infected individuals among the monkeys held in captivity. The findings of this work suggest that proximity of monkeys and infected rats and their exposure to infected fleas may be responsible for the host switching of T. Iewisi from their natural rodent species to primates. This and previous studies reporting T. lewisi in humans suggest that this trypanosome can cause sporadic and opportunistic fleaborne infection in primates. (C) 2010 Elsevier B.V. All rights reserved.

A hybrid case adaptation approach for case-based reasoning

Case-Based Reasoning is a methodology for problem solving based on past experiences. This methodology tries to solve a new problem by retrieving and adapting previously known solutions of similar problems. However, retrieved solutions, in general, require adaptations in order to be applied to new contexts. One of the major challenges in Case-Based Reasoning is the development of an efficient methodology for case adaptation. The most widely used form of adaptation employs hand coded adaptation rules, which demands a significant knowledge acquisition and engineering effort. An alternative to overcome the difficulties associated with the acquisition of knowledge for case adaptation has been the use of hybrid approaches and automatic learning algorithms for the acquisition of the knowledge used for the adaptation. We investigate the use of hybrid approaches for case adaptation employing Machine Learning algorithms. The approaches investigated how to automatically learn adaptation knowledge from a case base and apply it to adapt retrieved solutions. In order to verify the potential of the proposed approaches, they are experimentally compared with individual Machine Learning techniques. The results obtained indicate the potential of these approaches as an efficient approach for acquiring case adaptation knowledge. They show that the combination of Instance-Based Learning and Inductive Learning paradigms and the use of a data set of adaptation patterns yield adaptations of the retrieved solutions with high predictive accuracy.

Ni-Zn-Sm nanopowder ferrites: Morphological aspects and magnetic properties

Ni-Zn ferrites have been widely used in components for high-frequency range applications due to their high electrical resistivity, mechanical strength and chemical stability. Ni-Zn ferrite nanopowders doped with samarium with a nominal composition of Ni0.5Zn0.5Fe2-xSmxO4 (x = 0.0, 0.05, and 0.1 mol) were obtained by combustion synthesis using nitrates and urea as fuel. The morphological aspects of Ni-Zn-Sm ferrite nanopowders were investigated by X-ray diffraction, nitrogen adsorption by BET, sedimentation, scanning electron microscopy and magnetic properties. The results indicated that the Ni-Zn-Sm ferrite nanopowders were composed of soft agglomerates of nanoparticles with a high surface area (55.8-64.8 m(2)/g), smaller particles (18-20 nm) and nanocrystallite size particles. The addition of samarium resulted in a reduction of all the magnetic parameters evaluated, namely saturation magnetization (24-40 emu/g), remanent magnetization (2.2-3.5 emu/g) and coercive force (99.3-83.3 Oe). (c) 2007 Elsevier B. V. All rights reserved.

Associating biosensing properties with the morphological structure of multilayers containing carbon nanotubes on field-effect devices

The control of molecular architecture provided by the layer-by-layer (LbL) technique has led to enhanced biosensors, in which advantageous features of distinct materials can be combined. Full optimization of biosensing performance, however, is only reached if the film morphology is suitable for the principle of detection of a specific biosensor. In this paper, we report a detailed morphology analysis of LbL films made with alternating layers of single-walled carbon nanotubes (SWNTs) and polyamidoamine (PAMAM) dendrimers, which were then covered with a layer of penicillinase (PEN). An optimized performance to detect penicillin G was obtained with 6-bilayer SWNT/PAMAM LbL films deposited on p-Si-SiO(2)-Ta(2)O(5) chips, used in biosensors based on a capacitive electrolyte-insulator-semiconductor (EIS) and a light-addressable potentiometric sensor (LAPS) structure, respectively. Field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) images indicated that the LbL films were porous, with a large surface area due to interconnection of SWNT into PAMAM layers. This morphology was instrumental for the adsorption of a larger quantity of PEN, with the resulting LbL film being highly stable. The experiments to detect penicillin were performed with constant-capacitance (Con Cap) and constant-current (CC) measurements for EIS and LAPS sensors, respectively, which revealed an enhanced detection signal and sensitivity of ca. 100 mV/decade for the field-effect sensors modified with the PAMAM/SWNT LbL film. It is concluded that controlling film morphology is essential for an enhanced performance of biosensors, not only in terms of sensitivity but also stability and response time. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Influence of different solvents on the structural, optical and morphological properties of CdS nanoparticles

CdS is one of the most important II-VI semiconductors, with applications in solar cells, optoelectronics and electronic devices. CdS nanoparticles were synthesized via microwave-assisted solvothermal technique. Structural and morphological characterization revealed the presence of crystalline structures presenting single phase with different morphologies such as ""nanoflowers"" and nanoplates depending on the solvent used. Optical characterization was made by diffuse reflectance and photoluminescence spectroscopy, revealing the influence of the different solvents on the optical properties due to structural defects generated during synthesis. It is proposed that these defects are related to sulfur vacancies, with higher concentration of defects for the sample synthesized in ethylene glycol in comparison with the one synthesized in ethylene diamine. (C) 2011 Elsevier B.V. All rights reserved.

A Morphological View of the Sodium 4,4 `-Distyrylbiphenyl Sulfonate Fluorescent Brightness Distribution on Regenerated Cellulose Fibers

Evidence of the sorption of the whitening agent sodium 4,4`-distyrylbiphenyl sulfonate in the presence of the anionic surfactant sodium dodecylsulfate or the cationic surfactant dodecyl trimethyl ammonium chloride on regenerated cellulose fibers is given by several microscopy techniques. Scanning electron microscopy provided images of the cylindrical fibers with dimensions of 3.5 cm (length) and 13.3 mu m (thickness), with empty cores of 1 mu m diameter and a smooth surface. Atomic force microscopy showed a fiber surface with disoriented nanometric domains using both tapping-mode height and phase image modes. Atomic force microscopy also showed that the whitening agent and surfactant molecules were sorbed onto the fiber surface, in agreement with the adsolubilization sorption model. Transmission electron microscopy showed fibers with nanometric parallel cylinders, surrounded by holes where the fluorescent whitening molecules accumulated. On the basis of these techniques, we conclude that the sorption process occurs preferentially on the fiber surface in contact with the water solution, and under saturated conditions, the whitening agent penetrates into the pores and are simultaneously sorbed on the pore walls bulk, forming molecular aggregates. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 2321-2327, 2010

Multilevel Training of Binary Morphological Operators

The design of binary morphological operators that are translation-invariant and locally defined by a finite neighborhood window corresponds to the problem of designing Boolean functions. As in any supervised classification problem, morphological operators designed from a training sample also suffer from overfitting. Large neighborhood tends to lead to performance degradation of the designed operator. This work proposes a multilevel design approach to deal with the issue of designing large neighborhood-based operators. The main idea is inspired by stacked generalization (a multilevel classifier design approach) and consists of, at each training level, combining the outcomes of the previous level operators. The final operator is a multilevel operator that ultimately depends on a larger neighborhood than of the individual operators that have been combined. Experimental results show that two-level operators obtained by combining operators designed on subwindows of a large window consistently outperform the single-level operators designed on the full window. They also show that iterating two-level operators is an effective multilevel approach to obtain better results.

INSECT CHYMOTRYPSINS: CHLOROMETHYL KETONE INACTIVATION AND SUBSTRATE SPECIFICITY RELATIVE TO POSSIBLE COEVOLUTIONAL ADAPTATION OF INSECTS AND PLANTS

Insect digestive chymotrypsins are present in a large variety of insect orders but their substrate specificity still remains unclear. Ewer insect chymotrypsins from 3 different insect orders (Dictyoptera, Coleoptera and two Lepidoptera) were isolated using affinity chromatography. Enzymes presented molecular masses in the range of 20 to 31 kDa and pH optima in the range of 7.5 to 10.0. Kinetic characterization. using different, colorimetric and fluorescent substrates indicated that insect chymotrypsins differ from, bovine chymotrypsin in their primary specificity toward small substrates (like N-benzoyl-L-Tyr p-nitroanilide) rather than on their preference for large substrates (exemplified by Succynil-Ala-Ala-Pro-Phe P-nitroanilide). Chloromethyl ketones (TPCK, N-alpha-tosyl-L-Phe chloromethyl ketone and Z-GGF-CK, N-carbobenzoxy-Gly-Gly-phe-CK) inactivated all chymotrypsins legated. Inactivation rates follow apparent first-order kinetics with variable second order rates (TPCK, 42 to 130 M(-1)s(-1); Z-GGF-CK, 150 to 450 M(-1)s(-1) that may be remarkably low for S. frugiperda chymotrypsin (TPCK, 6 M(-1)s(-1); Z-GGF-CK, 6.1 M(-1) s(-1)). Homology modelling and sequence alignment showed that. in lepidopteran chymotrypsins, differences in the amino acid residues in the neighborhood of the catalytic His 57 may affect its pKa, value. This is Proposed as the cause of the decrease in His 57 reactivity toward chloromethyl ketones. Such amino acid replacement in the active site is proposed. to be an adaptation to the presence of dietary ketones. (C) 2009 Wiley Periodicals, Inc.

Phenolic matrices and sisal fibers modified with hydroxy terminated polybutadiene rubber: Impact strength, water absorption, and morphological aspects of thermosets and composites

The aim of the present work was to investigate the toughening of phenolic thermoset and its composites reinforced with sisal fibers, using hydroxyl-terminated polybutadiene rubber (HTPB) as both impact modifier and coupling agent. Substantial increase in the impact strength of the thermoset was achieved by the addition 10% of HTPB. Scanning electron microscopy (SEM) images of the material with 15% HTPB content revealed the formation of some rubber aggregates that reduced the efficiency of the toughening mechanism. In composites, the toughening effect was observed only when 2.5% of HTPB was added. The rubber aggregates were found located mainly at the matrix-fiber interface suggesting that HTPB could be used as coupling agent between the sisal fibers and the phenolic matrix. A composite reinforced with sisal fibers pre-impregnated with HTPB was then prepared; its SEM images showed the formation of a thin coating of HTPB on the surface of the fibers. The ability of HTBP as coupling agent between sisal fibers and phenolic matrix was then investigated by preparing a composite reinforced with sisal fibers pre-treated with HTPB. As revealed by its SEM images, the HTPB pre-treatment of the fibers resulted on the formation of a thin coating of HTPB on the surface of the fibers, which provided better compatibility between the fibers and the matrix at their interface, resulting in a material with low water absorption capacity and no loss of impact strength. (C) 2009 Elsevier B.V. All rights reserved.

Mechanical, thermal and morphological characterization of polypropylene/biodegradable polyester blends with additives

The (bio)degradation of polyolefins can be accelerated by modifying the level of crystallinity or by incorporation of carbonyl groups by adding pro-oxidants to masterbatches or through exposure to ultraviolet irradiation. In this work we sought to improve the degradation of PP by adding cobalt, calcium or magnesium stearate to Ecoflex(R), PP or Ecoflex(R)/PP blends. The effect of the pro-oxidants on biodegradability was assessed by examining the mechanical properties and fluidity of the polymers. PP had higher values for tensile strength at break and Young`s modulus than Ecoflex(R), and the latter had little influence on the properties of PP in Ecoflex(R)/PP blends. However, the presence of pro-oxidants (except for calcium) reduced these properties. All of the pro-oxidants enhanced the fluidity of PP, a phenomenon that facilitated polymer degradation at high temperatures. (C) 2009 Elsevier Ltd. All rights reserved.

The international marketing strategy of grocery retailers – the strategy of adaptation and standardization

Research question – The research question, that this study attempts to answer, is, what and why grocery retailers, which specifically work with the strategy of standardization, adapt in their marketing mix to the host market. Main adaptations are analyzed with regard to psychic distance in terms of consumer characteristics. Methodology – This study presents a qualitative research design. Secondary data, in-depth interviews and personal observations were used, in order to identify adaptations, which were conducted in a grocery retailer in Germany, which is its home market, and in Sweden, which is considered to be a host market. Findings – The main findings of this research indicate that grocery retailers that specifically work with the strategy of standardization, adopt their core strategy at the host market, in order to keep their economy of scale. However, the standardization strategy may cause negative financial results, which is why adaptations, in order to attract new customers, are required. Conclusively, a mix of both, the adaptation and standardization marketing strategy, has to be utilized.

Simplified follow-up after medical abortion using a low-sensitivity urinary pregnancy test and a pictorial instruction sheet in Rajasthan, India : study protocol and intervention adaptation of a randomised control trial

The World Health Organisation suggests that simplification of the medical abortion regime will contribute to an increased acceptability of medical abortion, among women as well as providers. It is expected that a home-based follow-up after a medical abortion will increase the willingness to opt for medical abortion as well as decrease the workload and service costs in the clinic. Trial design The study is a randomised, controlled, non-superiority trial . Methods Women screened to participate in the study are those with unwanted pregnancies and gestational ages equal to or less than nine weeks. Eligible women randomised to the home-based assessment group will use a low-sensitivity pregnancy test and a pictorial instruction sheet at home, while the women in the clinic follow-up group will return to the clinic for routine follow-up carried out by a doctor. The primary objective of the study is to evaluate the effectiveness of home-based assessment using a low-sensitivity pregnancy test and a pictorial instruction sheet 10-14 days after an early medical abortion. Providers or research assistants will not be blinded during outcome assessment. To ensure feasibility of the self-assessment intervention an adaption phase took place at the selected study sites before study initiation. This was to optimise and tailor-make the intervention and the study procedures and resulted in the development of the pictorial instruction sheet for how to use the low-sensitivity pregnancy test and the danger signs after a medical abortion. Discussion In this paper, we will describe the study protocol for a randomised control trial investigating the efficacy of simplified follow-up in terms of home-based assessment, 10-14 days after a medical abortion. Moreover, a description of the adaptation phase is included for a better understanding of the implementation of the intervention in a setting where literacy is low and the road-connections are poor. Trial registration: Clinicaltrials.gov NCT01827995. Registered 04 May 2013