Activity and selectivity of a {\text{Pd/}}\gamma {\text{ - Al}}_{\text{2}} {\text{O}}_{\text{3}} catalytic membrane in the partial hydrogenation reactions of acetylene and 1,3-butadiene

A ${\text{Pd/}}\gamma {\text{ - Al}}_{\text{2}} {\text{O}}_{\text{3}}$ membrane supported on a macroporous $\alpha {\text{ - Al}}_{\text{2}} {\text{O}}_{\text{3}}$ tube was prepared by sol–gel processing and used in the partial hydrogenation of acetylene and 1,3-butadiene. The average pore diameter of the ${\text{Pd/}}\gamma {\text{ - Al}}_{\text{2}} {\text{O}}_{\text{3}}$ membrane was 3.6 nm. The gases were separated by Knudsen diffusion. The activity and selectivity of the ${\text{Pd/}}\gamma {\text{ - Al}}_{\text{2}} {\text{O}}_{\text{3}}$ membrane was compared to that of ${\text{Pd/}}\gamma {\text{ - Al}}_{\text{2}} {\text{O}}_{\text{3}}$ catalysts used in a conventional packed bed reactor. The highest selectivity to the partially hydrogenated products occurred when the reactant was premixed with H₂ and was passed through the membrane wall.     

Converting Eucalyptus biomass into ethanol: Financial and sensitivity analysis in a co-current dilute acid process. Part II

The technical and financial performance of high yield Eucalyptus biomass in a co-current dilute acid pretreatment followed by enzymatic hydrolysis process was simulated using WinGEMS^® and Excel^®. Average ethanol yield per dry Mg of Eucalyptus biomass was approximately 347.6 L of ethanol (with average carbohydrate content in the biomass around 66.1%) at a cost of $0.49 L⁻¹ of ethanol, cash cost of ∼ $0.46 L⁻¹ and CAPEX of $1.03 L⁻¹ of ethanol. The main cost drivers are: biomass, enzyme, tax, fuel (gasoline), depreciation and labor. Profitability of the process is very sensitive to biomass cost, carbohydrate content (%) in biomass and enzyme cost. Biomass delivered cost was simulated and financially evaluated in Part I; here in Part II the conversion of this raw material into cellulosic ethanol using the dilute acid process is evaluated.     

Identification of the genetic variants of κ-casein in milk by isoelectric focusing electrophoresis

The genetic variants of κ-casein (κ-CN) A and B were analysed in milk from Holstein–Friesian (HF) and Jersey cows by means of isoelectric focusing (IEF) electrophoresis. Milk samples were obtained in triplicate from pure-breed HF and Jersey cows (three of each) to estimate the protein content, casein and purify κ-CN. The protein and casein contents in the milk from both breeds were statistically different ( P <  0.05). The κ-CN A migrates first with an isoelectric point (pI) of 7.2–7.3 and then B with a pI of 7.5–7.7. Differences in the expression proportion of both variants were detected.     

A study of the drainages of the pyrite mines of Aljustrel (Portugal)

Characterization of the pollution charge of drainages from pyrite mines of Aljustrel (Portugal) was made. Laboratory experiments were performed in order to recover copper by cementation and remove iron, zinc and acidity by neutralization with lime. It was found that the removal of the metal ions is completed when pH reaches a step at 5.0–5.5, whichever the ratio between Fe(II) and Fe(III).     

Methode rapide de dosage selectif des chlorophylles a et b utilisation de la separation par chromatographie liquide haute pressionA selective and rapid method of chlorophylls a and b separative determination by high-pressure liquid chromatography

The usual extraction methodology of the phytoplankton chlorophylls by acetone at 90% and their usual detection by spectrophotometry of the global extract at different wave lengths seem to be insufficient to many authors. With intent to improve this method (extraction, detection), we have verified first that methanol extraction was more effective than 90% acetone extraction, and we have set up a method of detection as simple and rapid as the usual one but which allows measuring the chlorophylls quantitatively and specifically, once they are separated. The chlorophylls a and b were separated by high-pressure liquid chromatography in reversed phase with a spherisorb ODS C₁₈ column eluted with methanol-water ($\text{97}\text{3}$) at a flow-rate of 1 ml min^?1; after being eluted they were detected by spectrofluorometry (excitation 427 nm and detection 470 nm) (Figs 1 and 2). This selective, sensitive rapid (20 min) determination can be automated by using an automatic injector and the recording on an integrator. The standardization of chlorophylls a and b was carried out with fluoranthen (internal standard) which does not want preparing again at every set of determinations (Fig. 3). This is a great advantage when we consider the fast degradation of the standards. This method allows using absolute methanol which is an extracting solvent more efficient than acetone 90% in the specific case of Scenedesmus subspicatus, whose pigments are known not to be easily extracted, and, in a broader sense, in the case of natural phytoplanktonic populations. To add BaCO₃ as a basic material during extraction is not recommended. This methodology may be used for biomass estimates by routine analysis as well as for the delicate measuring of pigments. Chromatographic profiles of Scenedesmus subspicatus extract and Seine river extract are presented in Figs 4 and 5.     

Characterization and FE analysis on the shear test of electronic materials

Adhesion is one of the main reliability concerns in electronic packages. However, the lack of standards to characterize this property makes it difficult to interpret the results. In this work, a series of shear tests have been conducted to evaluate adhesion strength of different electronic materials.Finite element analysis (FEA) is employed here to model the shear strength of microelectronic materials and to analyze the stress distribution in the specimen and substrate in order to understand this failure mechanism. The shear tool force and displacement at failure were measured experimentally and used as boundary condition for the FEA calculations.Several combinations of soft and stiff materials for specimens and substrates respectively have been evaluated in order to estimate the effects on the shear strength. The general trend from experimental and FEM results shows that soft specimens present a high concentration of stresses in the loaded surface while in the case of rigid specimens, the stresses are distributed in the whole area of contact between specimen and substrate. A proposal for calculating the shear strength was done.     

Boundary Element Modeling of the Realistic Human Body Exposed to Extremely-Low-Frequency (ELF) Electric Fields: Computational and Geometrical Aspects

This paper presents the human exposure assessment to high-voltage extremely-low-frequency (ELF) fields by the three-dimensional (3-D) boundary element method (BEM). The formulation is based on a realistic, anatomically based representation of the human body. The main objective is to analyze the influence of the relative position of the arms with respect to the body on the axial distribution of current density along the body and to determine the most vulnerable regions. Numerical results along head, neck, torso, abdomen, arms, legs, and ankles are presented and discussed in the case of grounded subject standing under power-distribution lines and in the vicinity of power transformer substations     

Device assessment of the electrical activity of threading dislocations in strained Ge epitaxial layers

It is shown that the high density of threading dislocations (TDs) and, more specifically, the high density of point defects associated with it and present in our strained Ge epitaxial layers on a Si_0.2Ge_0.8 relaxed buffer layer degrades the mobility and the leakage current of pMOSFETs and p⁺n junctions fabricated therein. Annealing in the range 550–650 °C prior to gate stack deposition improves the device performance, although there is no marked change in the TD density. From this, it is concluded that the annealing may reduce the density of point defects grown in during the epitaxial deposition.     

Interfacing Renewable Energy Sources to the Utility Grid Using a Three-Level Inverter

This paper presents a novel approach for the connection of renewable energy sources to the utility grid. Due to the increasing power capability of the available generation systems, a three-level three-phase neutral-point-clamped voltage-source inverter is selected as the heart of the interfacing system. A multivariable control law is used for the regulator because of the intrinsic multivariable structure of the system. A current source (playing the role of a generic renewable energy source) is connected to the grid using a three-level inverter in order to verify the good performance of the proposed approach. Large- and small-signal d-q state-space averaged models of the system are obtained and used to calculate the multivariable controller based on the linear quadratic regulator technique. This controller simultaneously regulates the dc-link voltage (to operate at the maximum power point of the renewable energy source), the mains power factor (the power is delivered to the grid at unity power factor), and the dc-link neutral-point voltage balance. With the model and regulator presented, a specific switching strategy to control the dc-link neutral-point voltage is not required. The proposed controller can be used for any application, since its nature makes possible the control of any system variable. The good performance of the presented interfacing solution in both steady-state and transient operation is verified through simulation and experimentation using a 1-kW neutral-point-clamped voltage-source-inverter prototype, where a PC-embedded digital signal processor board is used for the controller implementation