STRUCTURAL AND ELECTRONIC COUPLING OF ORGANIC HETEROAROMATIC MOLECULES ON INORGANIC SURFACES OF OXIDES

Many novel technologies base their main capabilities on the interface between organic semiconductors and dielectric surfaces. Understanding and manipulating its behaviour becomes then an important task for their development, from production cost to efficiency and better employment qualities. In the present thesis, I dealt the issue of molecular ordering and electronic properties at the organodielectric interfaces of four donor heteroaromatic molecules regarding the rutile-TiO2 (110) surface in an ultra-high vacuum (UHV) environment, combining some of them with a carbon allotrope as acceptor. The interface electronic structure, morphology, conformation and chemical interaction of in situ grown thin film of metal-free tetraphenyl porphyrin (2H-TPP), have been investigated by means of STM and/or electron spectroscopies. The surface sensitivity and chemical selectivity of soft X-ray photoemission (XPS) and near-edge X-ray absorption (NEXAFS) allowed to monitor the chemical state upon absorption and the orientation of their molecular plane and peripheral substituents. Free base tetraphenyl porphyrins adsorb on the oxygen rows, where they can spontaneously capture additional hydrogen atoms at their iminic nitrogens (4H-TPP). Both species aggregate into a commensurate phase at saturation coverage (1M), and upon sample heating a self-metalation reaction sets in at about 100\ubaC. The Ti atoms are extracted from the substrate by dehydrogenation of pyrrolic nitrogen atoms from the macrocyle, where remain coordinated to two underlying oxygen atoms. The adsorption geometry and molecular arrangement remain invariable across the self-metalation up to 300\ubaC. The possible manifestation of metal exchange with reactive Ti atoms must be considered when designing porphyrin sensytized solar cells due to the critical self-metalation temperature, close to its normal operating temperature. Thermal stability up to 450\ubaC is also demonstrated, with a phase symmetry change from oblique-(2x4) to rect-(2x6), keeping chemical states of both the molecular tetrapyrrolic macrocycle and the substrate unchanged, revealing by NEXAFS that the driving mechanism is the rotation of the phenyl terminations towards the substrate (flattening) promoting the partial cyclodehydrogenation of the molecules, and preserving the coordination of the macrocycle central pocket to the oxygen atoms through the self-metalation and the flattening reactions. Porphyrins trapped at the TiO2(110) surface demonstrate a high thermal stability making it a promising system for implementation in photocatalysis applications and photovoltaic devices. Another heteroaromatic molecules have been also investigated: tert-butyl tetraphenyl porphyrin (2h-tbTPP), octaethyl porphyrin (2H-OEP) and phtalocyanine (2H-Pc). The experimental results point to the existence of an unaffected reaction by the substituents, the hydrogenation of the macrocycle as deposited, converting its aza- nitrogen atoms into pyrrolic- nitrogen atoms. The self-metalation (i.e. incorporation of a Ti ion extracted from the substrate) was also demonstrated by X-ray spectroscopy for the four compounds but is accomplished at different temperature, starting at room temperature for the 2H-Pc, and at 100\ubaC for 2H-TPP and being completed at 200\ubaC for 2H-tbTPP and 250\ubaC for 2H-OEP, opening the possibility of a self-metalation of free-metal compounds and trans-metalation for metalated compounds due to the lower temperatures needed depending on the peripheral substituents, during the experimentation and development of devices with this compounds

Xylanolytic enzymes production by Aspergillus niger GS1 from solid-state fermentation on corn stover and their effect on ruminal digestibility

Hemicellulosic agricultural by-products such as corn stover (CS) are highly available materials which represent an opportunity to develop value added products. Native Aspergillus niger GS1 was used for solid-state fermentation (SSF) on alkali pre-treated CS (ACS) aimed to optimize xylanolytic enzymes production, and their effect on in vitro ruminal and true digestibility of ACS. Enzyme production was empirically modelled using a fractional factorial design 29-5, and the resulting significant factors were glucose, yeast extract and two mineral salts, which were arranged in a Draper-Lin optimization design at two levels. Predicted optimum xylanolytic activity of 33.6 U (mg protein)-1 was achieved at 48 hrs of SSF, and was validated by confirmatory experiments. ACS was incubated with a semipurified enzymatic extract (EE) showing a xylanolytic activity of 1600 U kg-1 dry ACS for 12 hrs before exposure to cow\u2019s ruminal liquid for 72 hrs, which led to 5% and 10% increase of in vitro ruminal and true digestibility, respectively. CS is a readily available by-product in different regions which after alkaline treatment and partial hydrolysis with the EE, may be advantageously used as supplement for ruminant feed

Inorganic, organic, and encapsulated minerals in vegetable meal based diets for Sparus aurata (Linnaeus, 1758)

Substituting fishmeal (FM) with vegetable meal (VM) can markedly affect the mineral composition of feeds, and may require additional mineral supplementation. Their bioavailability and optimal supplementation levels depend also on the form of delivery of minerals. The aim of the study was to determine the effect of different delivery forms of three major trace elements (Zn, Mn and Se) in a marine teleost. Gilthead sea bream juveniles of 22.5 g were fed a VM-based diet for 12 weeks that was either not supplemented with these minerals or supplemented with inorganic, organic, or encapsulated inorganic forms of minerals in triplicate and compared to a FM-based diet. Our results showed that mineral delivery form significantly affected the biochemical composition and morphology of posterior vertebrae. Supplementation of VM-based diets with inorganic forms of the target minerals significantly promoted growth, increased the vertebral weight and content of ash and Zn, enhanced bone mineralization and affected the vertebral shape. Conversely, encapsulation of inorganic minerals reduced fish growth and vertebral mineral content, whereas supplementation of organic minerals, enhanced bone osteogenesis by upregulating bone morphogenetic protein 2 (bmp2) gene and produced vertebrae with a larger length in relation to height. Furthermore, organic mineral forms of delivery downregulated the expression of oxidative stress related genes, such as Cu/Zn superoxide dismutase (Cu/Zn sod) and glutathione peroxidase 1 (gpx-1), suggesting thus that dietary minerals supplemented in the organic form could be reasonably considered more effective than the inorganic and encapsulated forms of supply

Evaluation of the efficacy of carbon nanotubes for delivering peptides into mitochondria

Mitochondrial (mt) diseases are devastating neurodegenerative pathologies due tomutations in nuclear or mt genes. Among mtDNA pathogenic mutations, more than one half have been identified in transfer RNA (tRNA) genes. These are responsible for a wide range of pathologies including myopathies, encephalopathies, cardiomyopathies and deafness for which no effective treatment is available at present. Therefore, new strategies to suppress their damaging effects are required to envisage therapeutic approaches for these diseases. Here we report data for carbon nanotube (CNT) derivatives showing that the conjugates bearing a specific peptide sequence are able to target the mitochondria in yeast and human monocyte cells while the control derivative without the peptide diffuses into the cytoplasm. Moreover the compounds do not affect cellular viability and cytotoxicity both in vitro and in vivo. Toxicity of the constructs is also assessed on the simple pluricellular model Caenorhabditis elegans

Induction of the expression of defence genes in Carica papaya fruit by methyl jasmonate and low temperature treatments

Abstract The defence mechanisms that are activated by methyl jasmonate (MJ) in fruits are not well understood. In this work, we studied the expression of defence genes in papaya fruit that are induced by the exposure to MJ and/or low temperatures. The papaya fruits \u2018Maradol\u2019 were randomly divided into two groups: one group was the untreated control and the other was treated with 10-4 M of MJ. Half of the fruits from each of the two groups were stored after treatment for 5 days at 5\ubaC and 2 days at 20\ubaC. We studied the expression levels of the pdf1.1 and pdf1.2 genes by amplification from expression libraries created from the pulp and skin tissues of the papaya fruit. As a reference, the mRNA level of the 18s ribosomal gene was used. In the skin tissue, the expression levels of the pdf1.1 and pdf1.2 genes were higher immediately after MJ treatment compared to the control. Furthermore, the expression of pdf1.2 remained high after MJ treatment and subsequent storage compared to the control. It was therefore concluded that the activation of the pdf1.1 and pdf1.2 genes forms part of the molecular defence mechanism in fruits that is activated by exposure to MJ. To our knowledge, this is the first study that analyzes the gene expression in papaya fruit that is induced by the exogenous application of methyl jasmonate and cold treatment

Experimental and numerical study for detection of rail defect

Condition monitoring methodologies have become an important part in maintenance programs for any type of structure towards prevention of catastrophic accidents. Natural frequency analysis is a useful methodology to evaluate the integrity condition of structural elements, such as: rotor beams, rails and almost every machine component. In this work, two techniques were applied for condition monitoring of rails: numerical, using the Finite Element Method (FEM), and experi- mental analysis. Sections of a rail 115RE had been characterized in the field for integral track section and laboratory for integral and artificial cracks conditions at different depths, in free-free boundary condition. Numerical simulation was used to compare and validate the experimental analysis. The changes in natural frequencies were observed as a function of the crack depth. It was performed a sensitivity analysis of natural frequency variation due to the influence of the crack depth and the section dimensions in order to explore the behaviour in modes of vibration. In addition, this monitoring technique can be potentially used as a criterion of when is necessary whether or not to eliminate the crack by gridding or replace the entire rail section. Finally, the finite element simulation was validated throughout natural frequencies measurements in the railway network

Batch culture growth of Chlorella zofingiensis on effluent derived from two-stage anaerobic digestion of two-phase olive mill solid waste

This paper presents the use of an effluent derived from two-stage anaerobic digestion of two-phase olive mill solid waste (OMSW) as a substrate for the production of Chlorella zofingiensis in batch mode. Chlorella zofingiensis when grown autotrophycally can accumulate significant quantities of valuable carotenoids which are used as an additive in fish and poultry farming, as colorants in foods and in health care products. It was found that two-phase OMSW previously treated by two-stage anaerobic digestion and further sterilized may be used as a culture medium for the microalgae Chlorella zofingiensis. Typical growth curves were obtained using both the above-mentioned anaerobic effluent and a synthetic medium. Total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) removals of 37% and 45% respectively were achieved in batch experiments after 11 days' operation time. The specific growth rate was lower when the treated effluent was used as the feed substrate (0.02 h-1) in comparison to the synthetic medium (0.03 h-1). The specific growth rates of the exponential phases were determined by using a first-order kinetic model applied to chlorophyll a (C a ) and total chlorophyll (TC) concentrations, as indirect measurements of the microalgae concentration. It was concluded that the effluent from two-stage anaerobic digestion of two-phase OMSW constituted an appropriate culture medium for the growth of Chlorella zofingiensis, providing a simple technology feasible for producing a very useful product for animal feeding

Antibacterial activity of the Antarctic bacterium Janthinobacterium sp. SMN 33.6 against multi-resistant Gram-negative bacteria

Background: The increment of resistant strains to commonly used antibiotics in clinical practices places in evidence the urgent need to search for new compounds with antibacterial activity. The adaptations that Antarctic microorganisms have developed, due to the extreme environment that they inhabit, promote them as a potential new source of active compounds for the control of microorganisms causing infections associated with health care. The aim of this study was to evaluate the antibacterial activity of an ethanol extract of the Antarctic bacterium Janthinobacterium sp., strain SMN 33.6, against nosocomial multi-resistant Gram-negative bacteria. Results: Inhibitory activity against human Gram-negative bacterial pathogens, with concentrations that varied between 0.5 and 16 \u3bcg ml-1, was demonstrated. Conclusions: The ethanolic extract of Janthinobacterium sp. SMN 33.6 possesses antibacterial activity against a chromosomal AmpC beta-lactamase-producing strain of Serratia marcescens , an extended-spectrum beta-lactamase-producing Escherichia coli and also against carbapenemase-producing strains of Acinetobacter baumannii and Pseudomonas aeruginosa . This becomes a potential and interesting biotechnological tool for the control of bacteria with multi-resistance to commonly used antibiotics

Burden of Self-reported Acute Gastrointestinal Illness in Cuba

Acute gastrointestinal illness is an important public-health issue worldwide. Burden-of-illness studies have not previously been conducted in Cuba. The objective of the study was to determine the magnitude, distribution, and burden of self-reported acute gastrointestinal illness in Cuba. A retrospective, cross-sectional survey was conducted in three sentinel sites during June-July 2005 (rainy season) and during November 2005\u2013January 2006 (dry season). Households were randomly selected from a list maintained by the medical offices in each site. One individual per household was selected to complete a questionnaire in a face-to-face interview. The case definition was three or more bouts of loose stools in a 24-hour period within the last 30 days. In total, 97.3% of 6,576 interviews were completed. The overall prevalence of acute gastrointestinal illness was 10.6%. The risk of acute gastrointestinal illness was higher during the rainy season (odds ratio [OR]=3.85, 95% confidence interval [CI] 3.18-4.66) in children (OR=3.12, 95% CI 2.24-4.36) and teens (OR=2.27, 95% CI 1.51-3.41) compared to people aged 25-54 years, in males (OR=1.24, 95% CI 1.04-1.47), and in the municipality of Santiago de Cuba (OR=1.33, 95% CI 1.11-1.61). Of 680 cases, 17.1-38.1% visited a physician, depending on sentinel site. Of the cases who visited a physician, 33.3-53.9% were requested to submit a stool sample, and of those, 72.7-100.0% complied. Of the cases who sought medical care, 16.7- 61.5% and 0-31.6% were treated with antidiarrhoeals and antibiotics respectively. Acute gastrointestinal illness represented a substantial burden of health compared to developed countries. Targeting the identified risk factors when allocating resources for education, food safety, and infrastructure might lower the morbidity associated with acute gastrointestinal illness

Total RNA quality of lyophilized and cryopreserved dormant grapevine buds

Background: Plant tissues must be preserved in their collection state, especially for genome-wide expression profile studies. Lyophilization is a feasible, affordable tool when fresh tissues cannot be shipped at ultralow temperatures from their origin to the place of analysis. In this study, the total RNA quality of dormant grapevine buds ( Vitis vinifera L. cv. \u2018Flame Seedless\u2019) of freeze-dried samples stored at room temperature conditions was evaluated and compared to that of cryopreserved (-80\ub0C) grapevine buds. Results: Good yield and quality of RNA were obtained from freeze-dried dormant buds stored at room temperature for 0, 3 and 6 weeks after they were lyophilized. Further experiments confirmed that the extracted total RNA could be used for actin and \u3b2-tubulin PCR gene amplification. Conclusion: High-quality RNA that is useful for downstream applications was obtained from freeze-dried dormant grapevine bud tissue, similarly to the RNA obtained from cryopreserved dormant grapevine buds