Hierarchical mesoporous Pd/ZSM-5 for the selective catalytic hydrodeoxygenation of m-cresol to methylcyclohexane

Mesopore incorporation into ZSM-5 enhances the dispersion of Pd nanoparticles throughout the hierarchical framework, significantly accelerating m-cresol conversion relative to a conventional microporous ZSM-5, and dramatically increasing selectivity towards the desired methylcyclohexane deoxygenated product. Increasing the acid site density further promotes m-cresol conversion and methylcyclohexane selectivity through efficient dehydration of the intermediate methylcyclohexanol.

Tail gas catalyzed N2O decomposition over Fe-beta zeolite. On the promoting role of framework connected AlO6 sites in the vicinity of Fe by controlled dealumination during exchange

A novel route to prepare highly active and stable N2O decomposition catalysts is presented, based on Fe-exchanged beta zeolite. The procedure consists of liquid phase Fe(III) exchange at low pH. By varying the pH systematically from 3.5 to 0, using nitric acid during each Fe(III)-exchange procedure, the degree of dealumination was controlled, verified by ICP and NMR. Dealumination changes the presence of neighbouring octahedral Al sites of the Fe sites, improving the performance for this reaction. The so-obtained catalysts exhibit a remarkable enhancement in activity, for an optimal pH of 1. Further optimization by increasing the Fe content is possible. The optimal formulation showed good conversion levels, comparable to a benchmark Fe-ferrierite catalyst. The catalyst stability under tail gas conditions containing NO, O2 and H2O was excellent, without any appreciable activity decay during 70 h time on stream. Based on characterisation and data analysis from ICP, single pulse excitation NMR, MQ MAS NMR, N2 physisorption, TPR(H2) analysis and apparent activation energies, the improved catalytic performance is attributed to an increased concentration of active sites. Temperature programmed reduction experiments reveal significant changes in the Fe(III) reducibility pattern with the presence of two reduction peaks; tentatively attributed to the interaction of the Fe-oxo species with electron withdrawing extraframework AlO6 species, causing a delayed reduction. A low-temperature peak is attributed to Fe-species exchanged on zeolitic AlO4 sites, which are partially charged by the presence of the neighbouring extraframework AlO6 sites. Improved mass transport phenomena due to acid leaching is ruled out. The increased activity is rationalized by an active site model, whose concentration increases by selectively washing out the distorted extraframework AlO6 species under acidic (optimal) conditions, liberating active Fe species.

Analysis of the tip roundness effects on the micro- and macroindentation response of elastic-plastic materials

In this work, the effects of indenter tip roundness oil the load-depth indentation curves were analyzed using finite element modeling. The tip roundness level was Studied based on the ratio between tip radius and maximum penetration depth (R/h(max)), which varied from 0.02 to 1. The proportional Curvature constant (C), the exponent of depth during loading (alpha), the initial unloading slope (S), the correction factor (beta), the level of piling-up or sinking-in (h(c)/h(max)), and the ratio h(max)/h(f) are shown to be strongly influenced by the ratio R/h(max). The hardness (H) was found to be independent of R/h(max) in the range studied. The Oliver and Pharr method was successful in following the variation of h(c)/h(max) with the ratio R/h(max) through the variation of S with the ratio R/h(max). However, this work confirmed the differences between the hardness values calculated using the Oliver-Pharr method and those obtained directly from finite element calculations; differences which derive from the error in area calculation that Occurs when given combinations of indented material properties are present. The ratio of plastic work to total work (W(p)/W(t)) was found to be independent of the ratio R/h(max), which demonstrates that the methods for the Calculation of mechanical properties based on the *indentation energy are potentially not Susceptible to errors caused by tip roundness.

Identification of new ozonation disinfection byproducts of 17 beta-estradiol and estrone in water

Estrogens are a class of micro-pollutants found in water at low concentrations (in the ng L(-1) range), but often sufficient to exert estrogenic effects due to their high estrogenic potency. Disinfection of waters containing estrogens through oxidative processes has been shown to lead to the formation of disinfection byproducts, which may also be estrogenic. The present work investigates the formation of disinfection byproducts of 17 beta-estradiol (E2) and estrone (E1) in the treatment of water with ozone. Experiments have been carried out at two different concentrations of the estrogens in ground water (100 ng L(-1) and 100 mu g L(-1)) and at varying ozone dosages (0-30 mg L(-1)). Detection of the estrogens and their disinfection byproducts in the water samples has been performed by means of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with a triple quadrupole (QqQ) and a quadrupole-time of flight (QqTOF) instrument. Both E2 and El have been found to form two main byproducts, with molecular mass (MM) 288 and 278 in the case of E2, and 286 and 276 in the case of El, following presumably the same reaction pathways. The E2 byproduct with MM 288 has been identified as 10epsilon-17beta-dihydroxy-1,4-estradieno-3-one (DEO), in agreement with previously published results. The molecular structures and the formation pathways of the other three newly identified byproducts have been suggested. These byproducts have been found to be formed at both high and low concentrations of the estrogens and to be persistent even after application of high ozone dosages. (C) 2011 Elsevier Ltd. All rights reserved.

Acquired tolerance of tomato (Lycopersicon esculentum cv. Micro-Tom) plants to cadmium-induced stress

The effects of varying concentrations of cadmium (Cd) on the development of Lycopersicon esculentum cv. Micro-Tom (MT) plants were investigated after 40 days (vegetative growth) and 95 days (fruit production), corresponding to 20 days and 75 days of exposure to CdCl(2), respectively. Inhibition of growth was clearly observed in the leaves after 20 days and was greater after 75 days of growth in 1 mM CdCl(2), whereas the fruits exhibited reduced growth following the exposure to a concentration as low as 0.1 mM CdCl(2). Cd was shown to accumulate in the roots after 75 days of growth but was mainly translocated to the upper parts of the plants accumulating to high concentrations in the fruits. Lipid peroxidation was more pronounced in the roots even at 0.05 mM CdCl(2) after 75 days, whereas in leaves, there was a major increase after 20 days of exposure to 1 mM CdCl(2), but the fruit only exhibited a slight significant increase in lipid peroxidation in plants subjected to 1 mM CdCl(2) when compared with the control. Oxidative stress was also investigated by the analysis of four key antioxidant enzymes, which exhibited changes in response to the increasing concentrations of Cd tested. Catalase (EC 1.11.1.6) activity was shown to increase after 75 days of Cd treatment, but the major increases were observed at 0.1 and 0.2 mM CdCl(2), whereas guaiacol peroxidase (EC 1.11.1.7) did not vary significantly from the control in leaves and roots apart from specific changes at 0.5 and 1 mM CdCl(2). The other two enzymes tested, glutathione reductase (EC 1.6.4.2) and superoxide dismutase (SOD, EC 1.15.1.1), did not exhibit any significant changes in activity, apart from a slight decrease in SOD activity at concentrations above 0.2 mM CdCl(2). However, the most striking results were obtained when an extra treatment was used in which a set of plants was subjected to a stepwise increase in CdCl(2) from 0.05 to 1 mM, leading to tolerance of the Cd applied even at the final highest concentration of 1 mM. This apparent adaptation to the toxic effect of Cd was confirmed by biomass values being similar to the control, indicating a tolerance to Cd acquired by the MT plants.

Characterization of pore size distributions of mesoporous materials from adsorption isotherms

In this article, a new hybrid model for estimating the pore size distribution of micro- and mesoporous materials is developed, and tested with the adsorption data of nitrogen, oxygen, and argon on ordered mesoporous materials reported in the literature. For the micropore region, the model uses the Dubinin-Rudushkevich (DR) isotherm with the Chen-Yang modification. A recent isotherm model of the authors for nonporous materials, which uses a continuum-mechanical model for the multilayer region and the Unilan model for the submonolayer region, has been extended for adsorption in mesopores. The experimental data is inverted using regularization to obtain the pore size distribution. The present model was found to be successful in predicting the pore size distribution of pure as well as binary physical mixtures of MCM-41 synthesized with different templates, with results in agreement with those from the XRD method and nonlocal density functional theory. It was found that various other recent methods, as well as the classical Broekhoff and de Beer method, underpredict the pore diameter of MCM-41. The present model has been successfully applied to MCM-48, SBA's, CMK, KIT, HMS, FSM, MTS, mesoporous fly ash, and a large number of other regular mesoporous materials.

Environmental influence on the stress corrosion cracking of rock bolts

In order to understand rock bolt Stress Corrosion Cracking (SCC), a series of experiments have been performed in Linearly Increasing Stress Test (LIST) apparatus. One series of experiments determined the threshold stress of various bolt metallurgies (900 MPa for Steel A, and 800 MPa for Steel B and C). The high values of threshold stress suggest that SCC begins in rock bolts when they are sheared by moving rock strata. Typical crack velocity values have been measured to be 2.5 x 10(-8) m s(-1), indicating that there is not much benefit for rock bolt steel of higher fracture toughness. Another series of experiments were performed to understand the environmental conditions causing SCC of steel A and galvanised Steel A rock bolt steel. SCC only occurred for environmental conditions for which produce hydrogen on the sample surface, leading to hydrogen embrittlement and SCC. Fracture surfaces of LIST samples failed by SCC were found to display the same fracture regions as fracture surfaces of rock bolts failed in service by SCC: Tearing Topography Surface (TTS), Corrugated Irregular Surface (CIS), quasi Micro Void Coalescence (qMVC) and Fast Fracture Surface (FFS). Water chemistry analysis were carried out on samples collected from various Australian mines in order to compare laboratory electrolyte conditions to those found in underground mines.

A incubação das micro, pequenas e médias empresas (MPMEs) em Portugal : uma discussão sobre custos de transacção, dimensão competitiva e a cadeia de valor

RESUMO: Este trabalho tem por objectivo discutir as formas como as incubadoras de empresas contribuem para a criação da cadeia de valores de Micros, Pequenas e Médias Empresas (MPMEs) permitindo a redução dos seus custos de transacção. Para melhor compreender a forma como se reduzem os custos de transacção é importante conhecer os pressupostos comportamentais que provocam a existência de tais custos: a racionalidade limitada, porque a nossa forma de pensar tem limitações; e o oportunismo, porque há pessoas com comportamentos desonestos envolvidas no negócio. O verdadeiro poder explicativo da teoria dos custos de transacção está, no entanto, na análise de três variáveis que determinam se esses custos serão mais baixos numa estrutura hierárquica ou num mercado. Estas três variáveis são: a especificidade de activos - se uma transacção envolve ou não activos específicos à actividade da empresa; a incerteza - qual o grau de incerteza em encontrar um produto ou serviço externo à empresa; e a frequência - e se um bem ou serviço é frequentemente utilizado ou não. As incubadoras de empresas são actualmente consideradas como uma iniciativa essencial ao desenvolvimento socioeconómico regional, e nacional. Estas instituições contribuem para corrigir ineficiências no mercado, conferindo às empresas uma capacidade de inovação tecnológica que garante empregos e a criação de riquezas, aumentando o bem-estar da sociedade. O sucesso da sua actuação resume-se à capacidade para gerar dimensões virtuais que contribuem para a cadeia de valores, permitindo as MPMEs, a redução dos seus custos de transacção. ABSTRACT: This work aims to discuss the relevant forms how incubators contribute to the value chain of a in micro, small and medium enterprises (MSME´s) reducing their transaction costs. To better understand how transaction costs can be reduced one must recognize the behavioral assumptions that are behind there existence; bounded rationality - because our way of thinking has limitations and opportunism - because there are dishonest people involved in the business. The true cost theory´s explanatory power comes from the analyses of the three variables that determine whether those costs will be lower in a hierarchical structure or a market structure. These three variables are: specificity of assets - if the transaction involves or not specific assets in for the firm´s activity; the uncertainty - what is the degree of uncertainty in finding a product or service external to the firm; and the frequency - what is the frequency of the good or service use. Business incubators are currently regarded as a key initiative for the national or regional economic development. The institutions contribute to correct market inefficiencies, improving the capacity of firms to produce technological innovations that guaranty jobs and wealth creation increasing welfare. The success of this all boils down to the capacity to create virtual dimensions that contributes to the MSME´s value chain reducing transaction costs.

Modification of MOR by desilication treatments: Structural, textural and acidic characterization

The effect of several desilication experimental parameters (base concentration, temperature and time) on the characteristics of MOR zeolite was studied. The samples were characterized by X-ray diffraction, Al-27 and Si-29 MAS-NMR, chemical analysis, and FTIR (framework vibration region). The textural characterization was made by N-2 adsorption and the acidity was evaluated by pyridine adsorption followed by FTIR and by the catalytic model reaction of n-heptane cracking. The alkaline treatments promoted the Si extraction from the zeolite framework, without considerable loss of crystallinity and, as it was envisaged, an important increase of the mesoporous structure was attained. A linear correlation between the number of framework Si per unit cell. N-Si and the asymmetric stretching wavenumber, nu(i), was observed. The acidity characterization shows that the desilicated samples exhibit practically the same acid properties than the parent HMOR zeolite. The optimum desilication conditions were those used to obtain sample M/0.2/85/2, i.e., sample treated with 0.2 M NaOH solution at 85 degrees C for 2 h.

Desilication of MOR zeolite: Conventional versus microwave assisted heating

MOR zeolites were modified via desilication treatments with NaOH, under conventional and microwave heating. The samples were characterized by powder X-ray diffraction, (27)Al and (29)Si NMR spectroscopy. TEM and N(2) adsorption at -196 degrees C. The acidity of the samples and the space available inside the pores were evaluated through a catalytic model reaction, the isomerization of m-xylene, for which the profiles of the coke thermal decomposition were also analyzed. Powder X-ray diffraction and (29)Si and (27)Al MNR results show that in comparison with conventional heating, microwave irradiation (a less time consuming process) leads to identical amount of Si extraction from the zeolite framework. With this treatment. in addition to the customary mesopores development promoted by conventional heating, a partial conversion of the zeolite microporosity into larger micropores, is observed. The microwave irradiated and conventionally heated samples show different catalytic behavior in the m-xylene isomerization model reaction. It was observed that, by controlling the experimental conditions, it is possible to obtain samples with catalytic properties closer to the parent material, which is also confirmed by the respective coke analysis. (C) 2011 Elsevier B.V. All rights reserved.

Tuneable micro- and nano-periodic structures in urethane/urea networks

Micro- and nano-patterned materials are of great importance for the design of new nanoscale electronic, optical and mechanical devices, ranging from sensors to displays. A prospective system that can support a designed functionality is elastomeric polyurethane thin films with nano- or micromodulated surface structures ("wrinkles"). These wrinkles can be induced on different lengthscales by mechanically stretching the films, without the need for any sophisticated lithographic techniques. In the present article we focus on the experimental control of the wrinkling process. A simple model for wrinkle formation is also discussed, and some preliminary results reported. Hierarchical assembly of these tunable structures paves the way for the development of a new class of materials with a wide range of applications, from electronics to biomedicine.

Aplicação de zeólitos hierárquicos a reacções de acilação de Friedel-Crafts

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química

A high throughput colorimetric assay of beta-1,3-D-glucans by Congo red dye

Mushroom strains contain complex nutritional biomolecules with a wide spectrum of therapeutic and prophylactic properties. Among these compounds, β-d-glucans play an important role in immuno-modulating and anti-tumor activities. The present work involves a novel colorimetric assay method for β-1,3-d-glucans with a triple helix tertiary structure by using Congo red. The specific interaction that occurs between Congo red and β-1,3-d-glucan was detected by bathochromic shift from 488 to 516 nm (> 20 nm) in UV–Vis spectrophotometer. A micro- and high throughput method based on a 96-well microtiter plate was devised which presents several advantages over the published methods since it requires only 1.51 μg of polysaccharides in samples, greater sensitivity, speed, assay of many samples and very cheap. β-d-Glucans of several mushrooms (i.e., Coriolus versicolor, Ganoderma lucidum, Pleurotus ostreatus, Ganoderma carnosum, Hericium erinaceus, Lentinula edodes, Inonotus obliquus, Auricularia auricular, Polyporus umbellatus, Cordyseps sinensis, Agaricus blazei, Poria cocos) were isolated by using a sequence of several extractions with cold and boiling water, acidic and alkaline conditions and quantified by this microtiter plate method. FTIR spectroscopy was used to study the structural features of β-1,3-d-glucans in these mushroom samples as well as the specific interaction of these polysaccharides with Congo red. The effect of NaOH on triple helix conformation of β-1,3-d-glucans was investigated in several mushroom species.

Cutaneous cancer stem cell maintenance is dependent on beta-catenin signalling.

Continuous turnover of epithelia is ensured by the extensive self-renewal capacity of tissue-specific stem cells. Similarly, epithelial tumour maintenance relies on cancer stem cells (CSCs), which co-opt stem cell properties. For most tumours, the cellular origin of these CSCs and regulatory pathways essential for sustaining stemness have not been identified. In murine skin, follicular morphogenesis is driven by bulge stem cells that specifically express CD34. Here we identify a population of cells in early epidermal tumours characterized by phenotypic and functional similarities to normal bulge skin stem cells. This population contains CSCs, which are the only cells with tumour initiation properties. Transplants derived from these CSCs preserve the hierarchical organization of the primary tumour. We describe beta-catenin signalling as being essential in sustaining the CSC phenotype. Ablation of the beta-catenin gene results in the loss of CSCs and complete tumour regression. In addition, we provide evidence for the involvement of increased beta-catenin signalling in malignant human squamous cell carcinomas. Because Wnt/beta-catenin signalling is not essential for normal epidermal homeostasis, such a mechanistic difference may thus be targeted to eliminate CSCs and consequently eradicate squamous cell carcinomas.

Tumor cell budding and laminin-5 expression in colorectal carcinoma can be modulated by the tissue micro-environment.

Expression of laminin-5 alpha3, beta3 and gamma2 protein subunits was investigated in colorectal adenocarcinomas using immunostaining and confocal microscopy. The laminin-5 heterotrimer was found in basement membranes and as extracellular deposits in tumor stroma. In contrast to the alpha3 subunit, which was under-expressed, the gamma2 and beta3 subunits were detected in the cytoplasm of carcinoma cells dissociating (budding) from neoplastic tubules, suggestive of focal alterations in laminin-5 assembly and secretion. Laminin-5 gamma2 or beta3 subunit-reactive budding carcinoma cells expressed cytokeratins but not vimentin; they did not proliferate and were not apoptotic. Furthermore, expression of laminin-5 gamma2 and beta3 subunits in budding cells was associated with focal under-expression of the E-cadherin-beta-catenin complex. Results from xenograft experiments showed that budding activity in colorectal adenocarcinomas could be suppressed when these tumors grew at ectopic s.c. sites in nude mice. In vitro, cultured colon carcinoma cells, but not adenoma-derived tumor cells, shared the laminin-5 phenotype expressed by carcinoma cells in vivo. Using colon carcinoma cell lines implanted orthotopically and invading the cecum of nude mice, the laminin-5-associated budding was restored, indicating that this phenotype is not only determined by tumor cell properties but also dependent on the tissue micro-environment. Our results indicate that both laminin-5 alpha3 subunit expression and cell-cell cohesiveness are altered in budding carcinoma cells, which we consider to be actively invading. We propose that the local tissue micro-environment contributes to these events.