Peptide-based low molecular weight gelators for the preparation of self-assembled materials

Low molecular weight gelators (LMWGs) based on pseudo-peptides are here studied for the preparation of supramolecular materials. These compounds can self-assemble through non-covalent interactions such as hydrogen bonds and π-π stacking, forming fibres and gels. A wide variety of materials can be prepared starting from these building blocks, which can be tuned and functionalised depending on the application. In this work, derivatives of the three aromatic amino acids L-Phenylalanine, L-Tyrosine and L-DOPA (3,4-dihydroxiphenylalanine) were synthesised and tested as gelators for water or organic solvents. First, the optimal gelating conditions were studied for each compound, varying concentration, solvent and trigger. Then the materials were characterised in terms of mechanical properties and morphology. Water remediation from dye pollution was the first focus of this work. Organogels were studied as absorbent of dyes from contaminated water. Hydrogels functionalised with TiO2 nanoparticles and graphene platelets were proposed as efficient materials for the photo-degradation of dyes. An efficient method for the incorporation of graphene inside hydrogels using the gelator itself as dispersant was proposed. In these materials a high storage modulus coexists with good self-healing and biocompatibility. The incorporation of a mineral phase inside the gel matrix was then investigated, leading to the preparation of composite organic/inorganic materials. In a first study, the growth of calcium carbonate crystals was achieved inside the hydrogel, which preserved its structure after crystal formation. Then the self-assembled fibres made of LMWGs were used for the first time instead of the polymeric ones as reinforcement inside calcium phosphate cements (CPCs) for bone regeneration. Gel-to-crystal transitions occurring with time in a metastable gel were also examined. The formation of organic crystals in gels can be achieved in multicomponent systems, in which a second gelator constitutes the independent gel network. Finally, some compounds unable to gelate were tested as underwater adhesives.

A DFT study on chemodivergent preparation of piperidinic and morpholinic heterocycles

The topic of this thesis is the DFT computational study of the mechanisms for the synthesis of chiral 3,4,5-trisubstituted piperidines and 2,6-disubstituted morpholines. The goal of this synthesis is to use, the same substrate containing two electrophilic sites: an α,β-unsaturated ester and a ketone, which evolve according to the nucleophile used (cyanide, phenyl sulfide) through different addition and cyclization reactions. A quaternary ammonium salt is used as a catalyst for these reactions, which leads to a diastereoisomeric excess both for the reactions of morpholine and piperidine products. Studies in silico of the pathways of these reactions explain the chemoselection and diasteroselection deriving from the two nucleophiles used. In this case of piperidine products, it was also possible to validate the hypothesis of a concerted nucleophilic addition mechanism on the α,β-unsaturated site and cyclization due to an intramolecular Michael addition.

Gross and Microscopic Morphological Anatomical Study of the Guinea Pig (Cavia porcellus) and the Capybara (Hydrochoerus hydrochaeris), Aimed at the Preparation of a Comparative Anatomical Atlas of the Different Systems

In recent years, there has been an exponential increase in the so-called “new pets”, including the domestic guinea pig (Cavia porcellus) and the capybara (Hydrochoerus hydrochaeris), two closely related Caviid rodents native to South America. Both historically bred for food purposes, they have more recently become increasingly popular as pets in the European and American continents, respectively. This led to an increasing veterinary interest in deepening the knowledge regarding their normal anatomy, as a basic contribution to other fields of veterinary medicine, including diagnostic imaging, surgery, and pathological anatomy. Being part of a bilateral framework co-tutelage agreement leading to a joint Doctoral Degree between the Alma Mater Studiorum of Bologna, Italy and the Universidad Nacional del Litoral of Santa Fe, Argentina, this research project was partly carried out in Italy (study of guinea pigs) and partly in Argentina (study of capybaras). It consisted in the macroscopic study, through anatomical dissections of carcasses of both species as well as the use of anatomical casts, and in the histological study of the various systems in the two species, and was aimed at creating a gross and microscopic comparative anatomical atlas. From the gross and microscopic morphological and morphometrical anatomical study of the different system of the guinea pig and capybara, several analogies and differences emerged. The creation of a comparative anatomical atlas of gross and microscopic anatomy of the capybara and the guinea pig might prove useful for clinical, zootechnical and research purposes.

Enxertia de plantas de pimentão em Capsicum spp. no manejo de nema tóides de galha

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effectof inoculum in the emulsification index of biossufactants produced by Bacillus velezensis using wheat bran as substrate in solid-state fermentation

Conselho Nacional de Desenvolvimento em Pesquisa (CNPq)

Influence of carbon source and inoculum type on anaerobic biomass adhesion on polyurethane foam in reactors fed with acid mine drainage

This paper analyzes the influence of carbon source and inoculum origin on the dynamics of biomass adhesion to an inert support in anaerobic reactors fed with acid mine drainage. Formic acid, lactic acid and ethanol were used as carbon sources. Two different inocula were evaluated: one taken from an UASB reactor and other from the sediment of a uranium mine. The values of average colonization rates and the maximum biomass concentration (C(max)) were inversely proportional to the number of carbon atoms in each substrate. The highest C(max) value (0.35 g TVS g(-1) foam) was observed with formic acid and anaerobic sludge as inoculum. Maximum colonization rates (v(max)) were strongly influenced by the type of inoculum when ethanol and lactic acid were used. For both carbon sources, the use of mine sediment as inoculum resulted in a v(max) of 0.013 g TVS g(-1) foam day(-1), whereas 0.024 g TVS g(-1) foam day(-1) was achieved with anaerobic sludge. (C) 2011 Elsevier Ltd. All rights reserved.

Ultrasound Irradiation Promoted Large-Scale Preparation in Aqueous Media and Antioxidant Activity of Azoles

The scaled-up preparation of 1H-pyrazole, 1-phenylpyrazole and isoxazole via sonocatalysis is reported. The products were isolated in good yields in short time reaction. These compounds had been assayed for antioxidant activity by ORAC and DPPH methodologies. The results showed that only 1-phenylpyrazole presented good antioxidant activity compared with Trolox(R).

Implications of specimen preparation and of surface contamination for the measurement of the grain boundary carbon concentration of steels using x-ray microanalysis in an UHVFESTEM

The purpose of the present investigation was to gain an understanding of the nature of the carbon contamination on the surface of standard steel transmission electron spectroscopy (TEM) specimens, the effect of exposure of a clean specimen to normal laboratory air, and the efficacy of plasma-cleaning treatments. This knowledge is a necessary prerequisite to the development of appropriate specimen preparation and/or specimen cleaning methods. X-ray photoelectron spectroscopy in combination with argon ion beam profiling was used to characterize the specimen surfaces of X65 steel and 316 stainless steel. The only clean carbon-free surface obtained was that during argon etching of the sample in the surface analysis chamber. Any exposure of a previously cleaned sample to laboratory air resulted in a rapid carbon (hydrocarbon) contamination of the sample surface and the development of surface oxidation, Plasma cleaning with subsequent exposure of the specimen to the laboratory air also resulted in a carbon-contaminated surface. This suggests that procedures of preparation of TEM specimens of steels outside an ultrahigh vacuum chamber are unlikely to result in the lowering of contamination rates on specimens to levels where measurements for carbon in the grain boundaries are possible. What is needed is a cleaning system as an integral part of the specimen insertion system into the field-emission scanning transmission electron microscope. This cleaning could be carried out by argon ion etching. Copyright (C) 2000 John Wiley & Sons, Ltd.

Heterogeneity in inoculum potential and effectiveness of arbuscular mycorrhizal fungi

Arbuscular mycorrhizae are symbiotic associations among glomalean fungi and plant roots that often lead to enhanced water and nutrient uptake and plant growth. We describe experiments to test whether inoculum potential of arbuscular mycorrhizal (AM) fungal communities varies spatially within a broadleaf temperate forest, and also whether there is variability in the effectiveness of AM fungal communities in enhancing seedling growth. Inoculum potential of arbuscular mycorrhizal fungi in a temperate broad-leaved forest did not vary significantly among sites. Inoculum potential, measured as the extent to which the roots of red maple seedlings that had been germinated on sterile sand and then transplanted into the forest, were colonized by AM fungi, was similar in floodplain and higher elevation sites. It was as similar under ectomycorrhizal oaks as it was under red maples and other AM tree species. It was also similar among sites with deciduous understory shrubs with arbuscular mycorrhizae (spicebush, Lindera benzoin) and those with evergreen vegetation with ericoid mycorrhizae (mountain laurel, Kalmia latifolia). Where spicebush was the dominant understory shrub, inoculum potential was greater under gaps in the canopy than within the understory. Survivorship of transplanted red maple seedlings varied significantly over sites but was not strongly correlated with measures of inoculum potential. In a greenhouse growth experiment, arbuscular mycorrhizal fungal communities obtained from tree roots from the forest had different effects on plant growth. Seedlings inoculated with roots of red maple had twice the leaf area after 10 wk of growth compared to the AM community obtained from roots of southern red oaks. Thus, although there appears to be little heterogeneity in inoculum potential in the forest, there are differences in the effectiveness of different inocula. These effects have the potential to affect tree species diversity in forests by modifying patterns of seedling recruitment.

Preparation and characterization of beta-lactam antibiotic as Ionic liquids and salts

With the increase of bacterial resistance a large number of therapeutic strategies have been used to fight different kind of infections. In recent years ionic liquids (ILs) have been increasing the popularity and the number of applications. First ionic liquids were used mainly as solvent in organic synthesis, but now they are used in analytical chemistry, separation chemistry and material science among others. Additional to significant developments in their chemical properties and applications, ionic liquids are now bringing unexpected opportunities at the interface of chemistry with the life sciences Ionic liquids (ILs) are currently defined as salts that are composed solely of cations and anions which melt below 100ºC. Our goal in this work is to explore the dual activity of the ionic liquids, due to the presence of two different ions, an ion with bacterial activity as a beta-lactam antibiotic and different kinds of cations. In this work the anions of ILs and salts were derived from three different antibiotics: ampicillin, penicillin and amoxicillin. The cations were derived from substituted ammonium, phosphonium pyridinium and methylimidazolium salts, such as: tetraethyl ammonium, trihexiltetradecilphosphonium, cetylpyridinium, choline (an essential nutrient), 1-ethyl-3-methylimidazolium, and 1-ethanol-3-methyl imidazolium structures. Commercial ammonium and phosponium halogen salts were first transformed into hydroxides. on ionic exchange column (Amberlite IRA-400) in methanol. The prepared hydroxides were then neutralized with beta-lactam antibiotics. After crystallization we obtained pure ILs and salts containing beta-lactam antibiotics. This work presents a novel method for preparation of new salts of antibiotics with low melting point and their characterization.

UV-fixed-thick-blotch preparation improves sensitivity of auramine staining.

We describe here a very simple modification of the auramine staining procedure based on preparation of a UV-fixed thick blotch which allowed us to reach an overall sensitivity of 0.82 (592 acid-fast bacillus [AFB]-positive specimens/722 initial respiratory specimens with positive mycobacterial culture) and sensitivities of 0.93 (526 AFB-positive specimens/564 culture-positive specimens) for Mycobacterium tuberculosis complex and 0.42 (66 AFB-positive specimens/158 culture-positive specimens) for nontuberculous mycobacteria.

Preparation and properties of starch-based biopolymers modified with difunctional isocyanates

The present work reports on the preparation of thermoplastic starch (TPS) modified in situ with a diisocyanate derivative. Evidence of the condensation reaction between the hydroxyl groups of starch and glycerol with the isocyanate function (NCO) was confirmed by FTIR analysis. The evolution of the properties of the ensuing TPS, in term of mechanical properties, microstructure, and water sensitivity, was investigated using tensile mechanical, dynamic mechanical thermal analysis (DMTA), X-ray diffraction (XRD), and water uptake. The results showed that the addition of isocyanate did not affect the crystallinity of the TPS and slightly reduced the water uptake of the material. The evolution of the mechanical properties with ageing became less pronounced by the addition of the isocyanate as their amount exceeded 4 to 6wt%.

Aging and the lateralization of oscillatory activities related to external and internal motor preparation

Selection of action may rely on external guidance or be motivated internally, engaging partially distinct cerebral networks. With age, there is an increased allocation of sensorimotor processing resources, accompanied by a reduced differentiation between the two networks of action selection. The present study examines the age effects on the motor-related oscillatory patterns related to the preparation of externally and internally guided movements. Thirty-two older and 30 younger adults underwent three delayed motor tasks with S1 as preparatory and S2 as imperative cue: Full, laterality instructed by S1 (external guidance); Free, laterality freely selected (internal guidance); None, laterality instructed by S2 (no preparation). Electroencephalogram (EEG) was recorded using 64 surface electrodes. Motor-Related Amplitude Asymmetries (MRAA), indexing the lateralization of oscillatory activities, were analyzed within the S1-S2 interval in the mu (9-12 Hz) and low beta (15-20 Hz) motor-related frequency bands. Reaction times to S2 were slower in older than younger subjects, and slower in the Free than in the Full condition in older subjects only. In the Full condition, there were significant mu MRAA in both age groups, and significant low beta MRAA only in older adults. The Free condition was associated with large mu MRAA in younger adults and limited low beta MRAA in older adults. In younger subjects, the lateralization of mu activity in both Full and Free conditions indicated effective external and internal motor preparation. In older subjects, external motor preparation was associated with lateralization of low beta in addition with mu activity, compatible with an increase of motor-related resources. In contrast, absence of mu and limited low beta lateralization in internal motor preparation was concomitant with reaction time slowing and suggested less efficient cerebral processes subtending free movement selection in older adults, indicating reduced capacity for internally driven action with age.

EEG alpha activity reflects motor preparation rather than the mode of action selection

Alpha-band activity (8-13 Hz) is not only suppressed by sensory stimulation and movements, but also modulated by attention, working memory and mental tasks, and could be sensitive to higher motor control functions. The aim of the present study was to examine alpha oscillatory activity during the preparation of simple left or right finger movements, contrasting the external and internal mode of action selection. Three preparation conditions were examined using a precueing paradigm with S1 as the preparatory and S2 as the imperative cue: Full, laterality instructed by S1; Free, laterality freely selected and None, laterality instructed by S2. Time-frequency (TF) analysis was performed in the alpha frequency range during the S1-S2 interval, and alpha motor-related amplitude asymmetries (MRAA) were also calculated. The significant MRAA during the Full and Free conditions indicated effective external and internal motor response preparation. In the absence of specific motor preparation (None), a posterior alpha event-related desynchronization (ERD) dominated, reflecting the main engagement of attentional resources. In Full and Free motor preparation, posterior alpha ERD was accompanied by a midparietal alpha event-related synchronization (ERS), suggesting a concomitant inhibition of task-irrelevant visual activity. In both Full and Free motor preparation, analysis of alpha power according to MRAA amplitude revealed two types of functional activation patterns: (1) a motor alpha pattern, with predominantly midparietal alpha ERS and large MRAA corresponding to lateralized motor activation/visual inhibition and (2) an attentional alpha pattern, with dominating right posterior alpha ERD and small MRAA reflecting visuospatial attention. The present results suggest that alpha oscillatory patterns do not resolve the selection mode of action, but rather distinguish separate functional strategies of motor preparation.

Evaluation of sample preparation methods and optimization of nickel determination in vegetable tissues

Nickel, although essential to plants, may be toxic to plants and animals. It is mainly assimilated by food ingestion. However, information about the average levels of elements (including Ni) in edible vegetables from different regions is still scarce in Brazil. The objectives of this study were to: (a) evaluate and optimize a method for preparation of vegetable tissue samples for Ni determination; (b) optimize the analytical procedures for determination by Flame Atomic Absorption Spectrometry (FAAS) and by Electrothermal Atomic Absorption (ETAAS) in vegetable samples and (c) determine the Ni concentration in vegetables consumed in the cities of Lorena and Taubaté in the Vale do Paraíba, State of São Paulo, Brazil. By means of the analytical technique for determination by ETAAS or FAAS, the results were validated by the test of analyte addition and recovery. The most viable method tested for quantification of this element was HClO4-HNO3 wet digestion. All samples but carrot tissue collected in Lorena contained Ni levels above the permitted by the Brazilian Ministry of Health. The most disturbing results, requiring more detailed studies, were the Ni concentrations measured in carrot samples from Taubaté, where levels were five times higher than permitted by Brazilian regulations.