Catalase in fluvial biofilms: a comparison between different extraction methods and example of application in a metal-polluted river

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore, been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase extraction from fluvial biofilms. Homogenization followed by glass bead disruption appeared to be the best compromise for catalase extraction. This method was then applied to a field study in a metal-polluted stream (Riou Mort, France). The most polluted sites were characterized by a catalase activity 4–6 times lower than in the low-polluted site. Results of the comparison process and its application are promising for the use of catalase activity as an early warning biomarker of toxicity using biofilms in the laboratory and in the field

Size Effect and Notch Size Effect in Metal Fatigue

It is a well known phenomenon that the constant amplitude fatigue limit of a large component is lower than the fatigue limit of a small specimen made of the same material. In notched components the opposite occurs: the fatigue limit defined as the maximum stress at the notch is higher than that achieved with smooth specimens. These two effects have been taken into account in most design handbooks with the help of experimental formulas or design curves. The basic idea of this study is that the size effect can mainly be explained by the statistical size effect. A component subjected to an alternating load can be assumed to form a sample of initiated cracks at the end of the crack initiation phase. The size of the sample depends on the size of the specimen in question. The main objective of this study is to develop a statistical model for the estimation of this kind of size effect. It was shown that the size of a sample of initiated cracks shall be based on the stressed surface area of the specimen. In case of varying stress distribution, an effective stress area must be calculated. It is based on the decreasing probability of equally sized initiated cracks at lower stress level. If the distribution function of the parent population of cracks is known, the distribution of the maximum crack size in a sample can be defined. This makes it possible to calculate an estimate of the largest expected crack in any sample size. The estimate of the fatigue limit can now be calculated with the help of the linear elastic fracture mechanics. In notched components another source of size effect has to be taken into account. If we think about two specimens which have similar shape, but the size is different, it can be seen that the stress gradient in the smaller specimen is steeper. If there is an initiated crack in both of them, the stress intensity factor at the crack in the larger specimen is higher. The second goal of this thesis is to create a calculation method for this factor which is called the geometric size effect. The proposed method for the calculation of the geometric size effect is also based on the use of the linear elastic fracture mechanics. It is possible to calculate an accurate value of the stress intensity factor in a non linear stress field using weight functions. The calculated stress intensity factor values at the initiated crack can be compared to the corresponding stress intensity factor due to constant stress. The notch size effect is calculated as the ratio of these stress intensity factors. The presented methods were tested against experimental results taken from three German doctoral works. Two candidates for the parent population of initiated cracks were found: the Weibull distribution and the log normal distribution. Both of them can be used successfully for the prediction of the statistical size effect for smooth specimens. In case of notched components the geometric size effect due to the stress gradient shall be combined with the statistical size effect. The proposed method gives good results as long as the notch in question is blunt enough. For very sharp notches, stress concentration factor about 5 or higher, the method does not give sufficient results. It was shown that the plastic portion of the strain becomes quite high at the root of this kind of notches. The use of the linear elastic fracture mechanics becomes therefore questionable.

Non-thermal emission from microquasar/ISM interaction

Context. The interaction of microquasar jets with their environment can produce non-thermal radiation as in the case of extragalactic outflows impacting on their surroundings. Significant observational evidence of jet/medium interaction in galactic microquasars has been collected in the past few years, although little theoretical work has been done regarding the resulting non-thermal emission. Aims. In this work, we investigate the non-thermal emission produced in the interaction between microquasar jets and their environment, and the physical conditions for its production. Methods. We developed an analytical model based on those successfully applied to extragalactic sources. The jet is taken to be a supersonic and mildly relativistic hydrodynamical outflow. We focus on the jet/shocked medium structure in its adiabatic phase, and assume that it grows in a self-similar way. We calculate the fluxes and spectra of the radiation produced via synchrotron, inverse Compton, and relativistic bremsstrahlung processes by electrons accelerated in strong shocks. A hydrodynamical simulation is also performed to investigate further the jet interaction with the environment and check the physical parameters used in the analytical model. Results. For reasonable values of the magnetic field, and using typical values of the external matter density, the non-thermal particles could produce significant amounts of radiation at different wavelengths, although they do not cool primarily radiatively, but by adiabatic losses. The physical conditions of the analytical jet/medium interaction model are consistent with those found in the hydrodynamical simulation. Conclusions. Microquasar jet termination regions could be detectable at radio wavelengths for current instruments sensitive to ~arcminute scales. At X-ray energies, the expected luminosities are moderate, although the emitter is more compact than the radio one. The source may be detectable by XMM-Newton or Chandra, with 1-10 arcsec of angular resolution. The radiation at gamma-ray energies may be within the detection limits of the next generation of satellite and ground-based instruments.

Welding of Sheet metal using Modified short arc MIG/MAG welding process

In this research work, the results of an investigation dealing with welding of sheet metals with diverse air gap using FastROOT modified short arc welding method and short circuit MAG welding processes have been presented. Welding runs were made under different conditions and, during each run, the different process parameters were continuously monitored. It was found that maximum welding speed and less HAZ are reached under specific welding conditions with FastROOT method with the emphasis on arc stability. Welding results show that modified short arc exhibits a higher electrode melting coefficient and with virtually spatter free droplet transition. By adjusting the short circuit duration the penetration can be controlled with only a small change in electrode deposition. Furthermore, by mixing pulsed MIG welding with modified arc welding the working envelope of the process is greatly extended allowing thicker material sections to be welded with improved weld bead aesthetics. FastROOT is a modified short arc welding process using mechanized or automated welding process based on dip transfer welding, characterized by controlled material deposition during the short circuit of the wire electrode to the workpiece.

Essential factors for control of the equilibrium in the reversible rearrangement of M3N@Ih-C80 fulleropyrrolidines: Exohedral functional groups versus endohedral metal clusters

The effects of exohedral moieties and endohedral metal clusters on the isomerization of M3N@Ih-C80 products from the Prato reaction through [1,5]-sigmatropic rearrangement were systematically investigated by using three types of fulleropyrrolidine derivatives and four different endohedral metal clusters. As a result, all types of derivatives provided the same ratios of the isomers for a given trimetallic nitride template (TNT) as the thermodynamic products, thus indicating that the size of the endohedral metal clusters inside C80 was the single essential factor in determining the equilibrium between the [6,6]-isomer (kinetic product) and the [5,6]-isomer. In all the derivatives, the [6,6]- and [5,6]-Prato adducts with larger metal clusters, such as Y3N and Gd3N, were equally stable, which is in good agreement with DFT calculations. The reaction rate of the rearrangement was dependent on both the substituent of exohedral functional groups and the endohedral metal-cluster size. Further DFT calculations and 13C NMR spectroscopic studies were employed to rationalize the equilibrium in the rearrangement between the [6,6]- and [5,6]-fulleropyrrolidines

Synthesis, characterization and thermal behaviour of solid-state compounds of benzoates with some bivalent transition metal ions

Solid-state MBz compounds, where M stands for bivalent Mn, Fe, Co, Ni, Cu and Zn and Bz is benzoate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy and complexometry were used to characterize and to study the thermal behaviour of these compounds. The procedure used in the preparation of the compounds via reaction of basic carbonates with benzoic acid is not efficient in eliminating excess acid. However the TG-DTA curves permitted to verify that the binary compounds can be obtained by thermosynthesis, because the benzoic acid can be eliminated before the thermal decomposition of these compounds. The results led to information about the composition, dehydration, thermal stability, thermal decomposition and structure of the isolated compounds. On heating, these compounds decompose in two (Mn, Co, Ni, Zn) or three (Fe, Cu) steps with formation of the respective oxide (Mn3O4, Fe2O3, Co3O4, NiO, CuO and ZnO) as final residue. The theoretical and experimental spectroscopic studies suggest a covalent bidentate bond between ligand and metallic center.

Adsorção de íons cobre(II) pela quitosana usando coluna em sistema sob fluxo hidrodinâmico

The adsorption of Cu(II) ions from aqueous solution by chitosan using a column in a closed hydrodynamic flow system is described. The adsorption capacities as a function of contact time of copper(II) ions and chitosan were determined by varying the ionic strength, temperature and the flow of the metal solution. The Langmuir model reproduced the adsorption isothermal data better than the Freundlich model. The experimental kinetic data correlate properly with the second-order kinetic reaction for the whole set of experimental adsorption conditions. The rate constants exercise great influence on the time taken for equilibrium to be established by complexation or electrostatic interaction between the amino groups of chitosan and the metal.

The interaction between sulfathiazole and cobalt(II): potentiometric studies

Potentiometric studies of sulfathiazole (HST) in the presence and absence of cobalt(II) were performed. Equilibrium constants for the formation of the detected species, [Co(ST)]+ and [Co(ST)(OH)], are reported. UV-Vis spectrophotometric measurements suggest that the coordination Co(II)-sulfathiazole might be through a N atom, which, in agreement with MO calculations, could be a thiazolic one. In spite of sulfonamides being better ligands at pH >7, [Co(ST)]+ was found at pH » 3.

Disseny d'una màquina carregadora de planxa a l'empresa Serralleria i Alumini Vilaró (S.A.V)

Les empreses sempre han buscat com optimitzar el màxim els seus recursos i ser més eficients a la hora de realitzar les tasques que li han estat encomanades. És per aquest motiu que constantment les empreses realitzen estudis i valoracions de com poder millorar dia a dia. Aquest fet no és diferenciador a l’empresa Serralleria i Alumini Vilaró (S.A.V), que dia a dia estudia com optimitzar els seus processos o de vegades introduir-ne de nous per tal d’expandir la seva oferta de serveis. L’empresa és dedica a la fabricació de peces metàl•liques el procés ja sigui només de tall i mecanitzat, plegat, soldadura, acabats en inoxidable, pintura i fins i tot embalatge pel que fa a la part productiva, respecte a la part d’oficina tècnica també ofereix serveis de desenvolupament de productes segons especificacions del client i reenginyeria de qualsevol producte, analitzant la part que és vol millorar. En l’actualitat l’empresa ha detectat una mancança que creu que es podria solucionar, el problema és que l’empresa disposa de varies màquines de tall, entre les quals hi ha una màquina de tall làser i el problema principal és que la càrrega de les planxes del calaix de magatzem a la bancada de la màquina es realitza o bé manualment o a través d’un gripper sostingut al pont grua, depenent del pes de la planxa a transportar. L’objectiu principal d’aquest treball és fer el disseny d’una màquina que permeti automatitzar el procés de transportar la planxa metàl•lica del calaix de magatzem dipositat sobre una taula mòbil a la bancada de la màquina de tall. El disseny que pretenem fer és complet començant per fer un disseny estructural de la màquina més els seus respectius càlculs, moviments que volem aconseguir, tria de components ( motors, sensors ...), elaboració d’un pressupost per poder fer una estimació i finalment la elaboració del programa de control de tota la màquina més la interacció amb la màquina a través d’una pantalla tàctil. Es a dir, el que pretenem és realitzar un projecte que puguem fabricar en la realitat utilitzant tota la informació continguda dins del mateix

Aplicação de Zr/Ti-PILC no processo de adsorção de Cu(II), Co(II) e Ni(II) utilizando modelos físico-químicos de adsorção e termodinâmica do processo

The aim of this investigation is to study how Zr/Ti-PILC adsorbs metals. The physico-chemical proprieties of Zr/Ti-PILC have been optimized with pillarization processes and Cu(II), Ni(II) and Co(II) adsorption from aqueous solution has been carried out, with maximum adsorption values of 8.85, 8.30 and 7.78 x10-1 mmol g-1, respectively. The Langmuir, Freundlich and Temkin adsorption isotherm models have been applied to fit the experimental data with a linear regression process. The energetic effect caused by metal interaction was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.

Effects of cobalt-chromium everolimus eluting stents or bare metal stent on fatal and non-fatal cardiovascular events: patient level meta-analysis

Objectives: To examine the safety and effectiveness of cobalt-chromium everolimus eluting stents compared with bare metal stents. Design: Individual patient data meta-analysis of randomised controlled trials. Cox proportional regression models stratified by trial, containing random effects, were used to assess the impact of stent type on outcomes. Hazard ratios with 95% confidence interval for outcomes were reported. Data sources and study selection: Medline, Embase, the Cochrane Central Register of Controlled Trials. Randomised controlled trials that compared cobalt-chromium everolimus eluting stents with bare metal stents were selected. The principal investigators whose trials met the inclusion criteria provided data for individual patients. Primary outcomes: The primary outcome was cardiac mortality. Secondary endpoints were myocardial infarction, definite stent thrombosis, definite or probable stent thrombosis, target vessel revascularisation, and all cause death. Results: The search yielded five randomised controlled trials, comprising 4896 participants. Compared with patients receiving bare metal stents, participants receiving cobalt-chromium everolimus eluting stents had a significant reduction of cardiac mortality (hazard ratio 0.67, 95% confidence interval 0.49 to 0.91; P=0.01), myocardial infarction (0.71, 0.55 to 0.92; P=0.01), definite stent thrombosis (0.41, 0.22 to 0.76; P=0.005), definite or probable stent thrombosis (0.48, 0.31 to 0.73; P<0.001), and target vessel revascularisation (0.29, 0.20 to 0.41; P<0.001) at a median follow-up of 720 days. There was no significant difference in all cause death between groups (0.83, 0.65 to 1.06; P=0.14). Findings remained unchanged at multivariable regression after adjustment for the acuity of clinical syndrome (for instance, acute coronary syndrome v stable coronary artery disease), diabetes mellitus, female sex, use of glycoprotein IIb/IIIa inhibitors, and up to one year v longer duration treatment with dual antiplatelets. Conclusions: This meta-analysis offers evidence that compared with bare metal stents the use of cobalt-chromium everolimus eluting stents improves global cardiovascular outcomes including cardiac survival, myocardial infarction, and overall stent thrombosis.

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.

Effects of cobalt-chromium everolimus eluting stents or bare metal stent on fatal and non-fatal cardiovascular events: patient level meta-analysis

Objectives: To examine the safety and effectiveness of cobalt-chromium everolimus eluting stents compared with bare metal stents. Design: Individual patient data meta-analysis of randomised controlled trials. Cox proportional regression models stratified by trial, containing random effects, were used to assess the impact of stent type on outcomes. Hazard ratios with 95% confidence interval for outcomes were reported. Data sources and study selection: Medline, Embase, the Cochrane Central Register of Controlled Trials. Randomised controlled trials that compared cobalt-chromium everolimus eluting stents with bare metal stents were selected. The principal investigators whose trials met the inclusion criteria provided data for individual patients. Primary outcomes: The primary outcome was cardiac mortality. Secondary endpoints were myocardial infarction, definite stent thrombosis, definite or probable stent thrombosis, target vessel revascularisation, and all cause death. Results: The search yielded five randomised controlled trials, comprising 4896 participants. Compared with patients receiving bare metal stents, participants receiving cobalt-chromium everolimus eluting stents had a significant reduction of cardiac mortality (hazard ratio 0.67, 95% confidence interval 0.49 to 0.91; P=0.01), myocardial infarction (0.71, 0.55 to 0.92; P=0.01), definite stent thrombosis (0.41, 0.22 to 0.76; P=0.005), definite or probable stent thrombosis (0.48, 0.31 to 0.73; P<0.001), and target vessel revascularisation (0.29, 0.20 to 0.41; P<0.001) at a median follow-up of 720 days. There was no significant difference in all cause death between groups (0.83, 0.65 to 1.06; P=0.14). Findings remained unchanged at multivariable regression after adjustment for the acuity of clinical syndrome (for instance, acute coronary syndrome v stable coronary artery disease), diabetes mellitus, female sex, use of glycoprotein IIb/IIIa inhibitors, and up to one year v longer duration treatment with dual antiplatelets. Conclusions: This meta-analysis offers evidence that compared with bare metal stents the use of cobalt-chromium everolimus eluting stents improves global cardiovascular outcomes including cardiac survival, myocardial infarction, and overall stent thrombosis.

Caracterização de lodo gerado em estações de tratamento de água: perspectivas de aplicação agrícola

The work reported here involved the characterization of sludges produced at water treatment plants in Jaboticabal-SP using FeCl3 as flocculant, and in Taquaritinga-SP and Manaus-AM using Al2(SO4)3 as flocculant. An evaluation was also made of the interaction of organic matter extracted from the sludges with different metal species. The results indicated that all the sludges produced at water treatment plants have an important agricultural potential and that their use depends on the characteristics of the raw water and the type of flocculant employed in conventional treatment. The humic substances extracted from the sludges showed different affinities for metal species, favoring eventual exchanges between potentially toxic metals and macro- and micronutrients. An alternative for the use of sludge in agriculture is to pretreat it to remove potentially toxic metals and enrich it with micro- and macronutrients that can be released to the plant.