Approximate solution to the speed of spreading viruses

Recently, it has been shown that the speed of virus infections can be explained by time-delayed reactiondiffusion [J. Fort and V. Me´ndez, Phys. Rev. Lett. 89, 178101 (2002)], but no analytical solutions were found. Here we derive formulas for the front speed, valid in appropriate limits. We also integrate numerically the evolution equations of the system. There is good agreement with both numerical and experimental speeds

Treatment of oily wastewater by ultrafiltration: The effect of different operating and solution conditions

In many industries, such as petroleum production, and the petrochemical, metal, food and cosmetics industries, wastewaters containing an emulsion of oil in water are often produced. The emulsions consist of water (up to 90%), oils (mineral, animal, vegetable and synthetic), surfactants and other contaminates. In view of its toxic nature and its deleterious effects on the surrounding environment (soil, water) such wastewater needs to be treated before release into natural water ways. Membrane-based processes have successfully been applied in industrial applications and are considered as possible candidates for the treatment of oily wastewaters. Easy operation, lower cost, and in some cases, the ability to reduce contaminants below existing pollution limits are the main advantages of these systems. The main drawback of membranes is flux decline due tofouling and concentration polarisation. The complexity of oil-containing systems demands complementary studies on issues related to the mitigation of fouling and concentration polarisation in membranebased ultrafiltration. In this thesis the effect of different operating conditions (factors) on ultrafiltration of oily water is studied. Important factors are normally correlated and, therefore, their effect should be studied simultaneously. This work uses a novel approach to study different operating conditions, like pressure, flow velocity, and temperature, and solution properties, like oil concentration (cutting oil, diesel, kerosene), pH, and salt concentration (CaCl2 and NaCl)) in the ultrafiltration of oily water, simultaneously and in a systematic way using an experimental design approach. A hypothesis is developed to describe the interaction between the oil drops, salt and the membrane surface. The optimum conditions for ultrafiltration and the contribution of each factor in the ultrafiltration of oily water are evaluated. It is found that the effect on permeate flux of the various factors studied strongly depended on the type of oil, the type of membrane and the amount of salts. The thesis demonstrates that a system containing oil is very complex, and that fouling and flux decline can be observed even at very low pressures. This means that only the weak form of the critical flux exists for such systems. The cleaning of the fouled membranes and the influence of different parameters (flow velocity, temperature, time, pressure, and chemical concentration (SDS, NaOH)) were evaluated in this study. It was observed that fouling, and consequently cleaning, behaved differently for the studied membranes. Of the membranes studied, the membrane with the lowest propensity for fouling and the most easily cleaned was the regenerated cellulose membrane (C100H). In order to get more information about the interaction between the membrane and the components of the emulsion, a streaming potential study was performed on the membrane. The experiments were carried out at different pH and oil concentration. It was seen that oily water changed the surface charge of the membrane significantly. The surface charge and the streaming potential during different stages of filtration were measured and analysed being a new method for fouling of oil in this thesis. The surface charge varied in different stages of filtration. It was found that the surface charge of a cleaned membrane was not the same as initially; however, the permeability was equal to that of a virgin membrane. The effect of filtration mode was studied by performing the filtration in both cross-flow and deadend mode. The effect of salt on performance was considered in both studies. It was found that salt decreased the permeate flux even at low concentration. To test the effect of hydrophilicity change, the commercial membranes used in this thesis were modified by grafting (PNIPAAm) on their surfaces. A new technique (corona treatment) was used for this modification. The effect of modification on permeate flux and retention was evaluated. The modified membranes changed their pore size around 33oC resulting in different retention and permeability. The obtained results in this thesis can be applied to optimise the operation of a membrane plant under normal or shock conditions or to modify the process such that it becomes more efficient or effective.

Investigating the spontaneous formation of SDS micelle in aqueous solution using a coarse-grained force field

A 1µs Molecular Dynamic simulation was performed with a realistic model system of Sodium Dodecyl Sulfate (SDS) micelles in aqueous solution, comprising of 360 DS-, 360 Na+ and 90000 water particles. After 300 ns three different micellar shapes and sizes 41, 68 and 95 monomers, were observed. The process led to stabilization in the total number of SDS clusters and an increase in the micellar radius to 2.23 nm, in agreement with experimental results. An important conclusion, is be aware that simulations employed in one aggregate, should be considered as a constraint. Size and shape distribution must be analyzed.

Solution thermodynamics of methocarbamol in some ethanol + water mixtures

Apparent thermodynamic functions, Gibbs energy, enthalpy and entropy of solution and mixing, for methocarbamol in ethanol + water mixtures, were evaluated from solubility data determined at temperatures from 293.15 K to 313.15 K and from calorimetric values of drug fusion. The drug solubility was greatest in the mixtures with 0.70 or 0.80 mass fraction of ethanol and lowest in neat water across all temperatures studied. Non-linear enthalpy-entropy compensation was found for the dissolution processes. Accordingly, solution enthalpy drives the respective processes in almost all the solvent systems analyzed.

Impregnação do ácido 12-tungstofosfórico em sílica - parte II: efeito de diferentes solventes na impregnação e atividade catalítica na esterificação metílica de ácido esteárico

Materials obtained by the immobilization of 12-tungstophosphoric acid (PTA) on silica using the method of impregnation with excess solution in distinct solvents (aqueous HCl, methanol:H2O, and acetonitrile) were evaluated for use as catalysts in the methyl esterification of stearic acid. Optimum conditions were established for the impregnation of 0.5 g (w/w) of PTA on amorphous silica, under stirring at 150 rpm for 24 h, using 20 mL of 0.1 mol L-1 HCl as the solvent. After calcination at 200 ºC, high conversions were obtained under mild reaction conditions, resulting in high turnover numbers. The catalyst was evaluated in ten catalytic cycles of use, where the activity was reduced only slightly, attesting its stability and the possibility to apply it to industrial production of methylesters.

Simple, mild, and highly efficient synthesis of 2-substituted benzimidazoles and bis-benzimidazoles

A new convenient method for preparation of 2-substituted benzimidazoles and bis-benzimidazoles is presented. In this method, o-phenylenediamines were condensed with bisulfite adducts of various aldehydes and di-aldehydes under neat conditions by microwave heating. The results were also compared with results of synthesis by conventional heating under reflux. Structures of the products were confirmed by infrared, ¹H- and 13C-NMR spectroscopy. Short reaction times, good yields, easy purification of products, and mild reaction conditions are the main advantages of this method.

Equilibrium studies of 2,2'-(5-bromo-6-methylpyrimidine-2,4-diyl)bis(azanediyl)dipropanoic acid with some transition-metal ions in aqueous solution

The stability constants of the 1:1 complexes formed between M2+ (M2+: Mn2+, Ni2+, Cu2+, or Cd2+) and BMADA2- (BMADA: 2,2'-(5-bromo-6-methylpyrimidine-2,4 diyl)bis(azanediyl)dipropanoic acid) were determined by potentiometric pH titration in aqueous solution (I = 0.1 mol L-1, NaNO3, 25 °C). The stability of the binary M - BMADA complexes is determined by the basicity of the carboxyl or amino groups. All the stability constants reported in this work exhibit the usual trend, and the order obtained was Mn2+< Ni2+ < Cu2+ > Cd2+. The observed stability order for BMADA approximately follows the Irving - Williams sequence. In the M - BMADA complexes, the M ion is able to form a macrochelate via the pyrimidine group of BMADA.

Determination of Mn2+ ion by solution scanometry as a new, simple and inexpensive method

In this research, scanometry was used as a new, simple, fast and inexpensive method for a colorimetric determination of Mn2+ ion in water samples and thermocouple wire through the use of periodate reagent in an acidic medium. The results showed the oxidization of colorless Mn2+ ion by periodate and the formation of a purplish MnO4- ion. The system had a linear range of 1.0 to 70.0 µg mL-1 Mn2+ ion with a detection limit of 0.314 µg mL-1 and a relative standard deviation of 2.77% for G color value. This method has the capability to determine low levels of Mn2+ ion in thermocouple wire and water samples.

COMPARAÇÃO E CONSTRUÇÃO DE REATORES DE "MILD" E "HARD ANODISATION" PARA FABRICAÇÃO DE ALUMINA ANÓDICA POROSA

The mild anodization (MA) reactor is exemplified for its operational simplicity and its excellent control over the experimental parameters that are involved in the anodization process. This method provides porous anodic alumina films with a regular cell-arrangement structure. This offers a better cost-benefit ratio than the other equipment configurations that are used to fabricate nanoporous structures (i.e., ion beam lithography). Conversely, the hard anodization (HA) reactor produces oxides at a rate that is 25 to 35 times faster than the MA reactor. The produced oxides also have greater layer thicknesses and interpore distance, and with a uniform nanopore spatial order (> 1000). In contrast to MA reactors, the construction of an HA reactor requires special components to maintain anodisation at a high potential regime. Herein, we describe and compare both reactors from a technical viewpoint.

Caracterização de um isolado do Pepper mild mottle virus que não quebra a resistência do gene L3 em Capsicum sp.

Sementes de pimenta (Capsicum baccatum) 'Dedo de Moça' destinadas ao plantio comercial e adquiridas no município de São Paulo, SP, analisadas quanto à presença de vírus, por meio de testes biológicos e sorológicos revelaram-se infetadas por uma estirpe do Pepper mild mottle virus (PMMoV). Para confirmar a identidade do isolado, promoveu-se a RT-PCR com oligonucleotídeos que flanqueiam a ORF da capa protéica de espécies do gênero Tobamovirus do subgrupo 1. Os fragmentos de DNA amplificados, quando seqüenciados e comparados com outros isolados de tobamovírus depositados no GenBank, apresentaram valores de identidade de nucleotídeos entre 94 e 100% com outras seqüências de PMMoV, inferiores a 75% para as demais espécies de tobamovírus do subgrupo I (Tobacco mosaic virus, Tomato mosaic virus e Odontoglossum ringspot virus) e 65% para os tobamovírus dos subgrupos II e III. O PMMoV-BR revelou 100% de identidade com isolados japoneses, sugerindo que este patógeno pode ter sido introduzido daquele país. A seqüência de aminoácidos deduzidos da capa protéica indicou também, que este isolado não é capaz de quebrar a resistência do gene L3 de Capsicum spp. Fato confirmado pelos sintomas causados nas hospedeiras diferenciais de Capsicum spp., verificando-se que este isolado não foi capaz de infetar plantas de C. chinense (L3) e C. chacoense (L4). Estes resultados confirmaram a importância da caracterização dos isolados de tobamovírus, fundamental para adequação de medidas de controle, principalmente, prevenindo a entrada e posterior disseminação do patógeno em novas áreas de cultivo.

Data Consistency by a Metadata Management Solution

This thesis consists of three main theoretical themes: quality of data, success of information systems, and metadata in data warehousing. Loosely defined, metadata is descriptive data about data, and, in this thesis, master data means reference data about customers, products etc. The objective of the thesis is to contribute to an implementation of a metadata management solution for an industrial enterprise. The metadata system incorporates a repository, integration, delivery and access tools, as well as semantic rules and procedures for master data maintenance. It targets to improve maintenance processes and quality of hierarchical master data in the case company’s informational systems. That should bring benefits to whole organization in improved information quality, especially in cross-system data consistency, and in more efficient and effective data management processes. As the result of this thesis, the requirements for the metadata management solution in case were compiled, and the success of the new information system and the implementation project was evaluated.

Estimation of existing cable systems in generator-busbar unit and choice the optimal solution for its modernization

The aim of this master’s thesis is to develop an algorithm to calculate the cable network for heat and power station CHGRES. This algorithm includes important aspect which has an influence on the cable network reliability. Moreover, according to developed algorithm, the optimal solution for modernization cable system from economical and technical point of view was obtained. The conditions of existing cable lines show that replacement is necessary. Otherwise, the fault situation would happen. In this case company would loss not only money but also its prestige. As a solution, XLPE single core cables are more profitable than other types of cable considered in this work. Moreover, it is presented the dependence of value of short circuit current on number of 10/110 kV transformers connected in parallel between main grid and considered 10 kV busbar and how it affects on final decision. Furthermore, the losses of company in power (capacity) market due to fault situation are presented. These losses are commensurable with investment to replace existing cable system.

Solution marketing characteristics and practices

The first objective of this master's thesis is to find out how the concepts solution and solution marketing are defined in the literature. In order to do so, solution marketing literature is reviewed widely. Another target is to identify the characteristics of solution marketing and to explain how solution marketing can be carried out. The final objective is to determine how well the described solution marketing practices are executed in the target company, and this will be studied with a survey. A solution can be described as a co-created and customized combination of products and services. Solution marketing aims at developing and anticipating customer's business needs and it involves close collaboration between customer and supplier. Solution marketing communication is targeted to a specific audience. It entails deep customer intimacy and is focused on understanding customer's business problem. Solution marketing also requires close collaboration between sales and marketing as well as customer focused mindset. Solution marketing can be executed by promoting thought leadership, presenting solution offering, creating close customer relationships and treating customers as individuals. Solution provider's whole organization must engage customer focus.