CO<Subscript>2</Subscript> adsorption at high pressures in MCM-41 and derived alkali-containing samples: the role of the textural properties and chemical affinity

The adsorption properties of N₂ and CO₂ of MCM-41 and derived alkali-containing samples were analyzed over a wide range of pressures (up to ~4500 kPa) and temperatures (between 30 and 300 °C). The high-pressure and high-temperature experiments were carried out on pure MCM-41 and K- and Na-impregnated derived samples. It was analyzed the influence of pressure and temperature on the CO₂ capture capacity on pure and impregnated samples. The adsorption performance was correlated to the structure and textural properties of the materials using X-ray diffraction and N₂ adsorption–desorption measurements. The addition of an alkaline element changes the textural properties of the material increasing the pore size, which positively affected the CO₂ adsorption capacity of these materials at high pressure. In addition, the isosteric heats of adsorption gave information about the chemical affinity between the impregnated materials and CO₂. The CO₂ adsorption at ~ 4500 kPa for the samples with 5 wt% Na at 100 and 200 °C were 77.98 and 9.79 mmol g^?1, respectively, while the pure MCM-41 adsorbs only 8.92 mmol g^?1.     

Technological characterization of Lactobacillus isolates from traditional Manchego cheese for potential use as adjunct starter cultures

Thirty Lactobacillus isolates from artisanal Manchego cheeses, 10 belonging to Lactobacillus plantarum and 20 belonging to Lactobacillus paracasei subsp. paracasei, were examined for potential use as adjunct cultures. Isolates were screened for acidifying and amino-biogenic capacity, for proteolytic, lipolytic, autolytic and aminopeptidase activities, and for sensory characteristics in UHT coagulated milk. Most of the lactobacilli displayed high aminopeptidase and autolytic activities and low acidifying activity. Only one isolate was able to produce tyramine. When growing on milk 53.3% of the Lb. paracasei subsp. paracasei isolates were able to produce pleasant flavours. Strains PBL210 (Lb. plantarum) and PBL213 and PBL226 (Lb. paracasei subsp. paracasei) presented the best technological characteristics, and also were still viable and with unaltered properties after freeze-drying and storage for 12 months. For these reasons, these strains could be good candidates for inclusion as adjuncts in a starter culture to manufacture industrial Manchego cheese.     

Ornamentation and Structure in the Representation of Renaissance Architecture in Spain

In the Renaissance, geometric perspectives became a method of architectural reasoning. We look at two works: a painting attributed to Pedro Berruguete and an engraving by Juan Bautista Villalpando in order to to discover the complex relationship between geometry and architecture, and in particular, the form of representation. Our analysis is based on the idea that geometric perspective meant architecture of the period was capable of graphically controlling reality through a high degree of geometric precision.     

Synthesis of macroporous ZrO2–Al2O3 mixed oxides with mesoporous walls, using polystyrene spheres as template

Macroporous ZrO₂–Al₂O₃ mixed oxides with mesoporous walls were synthesized. The three-dimensional interconnected macroporous structures, of inorganic zirconia–alumina mixed oxides containing different alumina compositions (25, 50, 100 wt%), were prepared by sol–gel method from inorganic precursors and using polystyrene microspheres with diameters of 685 and 1520 nm as templates. The final porous arrays with controllable pore size in the submicrometer range could be obtained by calcination of the organic template. The structural characteristics are discussed. The physicochemical characterization of the samples was carried out by N₂ physisorption (S_BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The shrinkage of pore diameter was approximately 35%, and the wall thickness of inorganic framework varied between 135 and 154 nm. The specific surface areas, of the samples, were between 123 and 287 m²/g, obtaining the largest surface area with the highest alumina contents and the smallest templates.     

A methodology to define a reconfigurable system architecture for a compact heat exchanger assembly machine

Due to the unexpected, fast, and constant changes of market requirements and the hypercompetency, robust manufacturing systems are needed that adjust easily to operational variability and the customized product supply. The simply substitution of components, software, hardware, and/or their adaptation by parameters resetting are an attractive option to face this challenge. Short product life cycles are an undeniable consequence and evidence of this. For this reason, to develop products or services profitably in the product manufacturing field, it is common to use the product family concept, which involves sharing components, functional features, and manufacturing process, both to make a cheaper product development process and to obtain customized products. A new generation of manufacturing systems that deploy characteristics such as adaptability and flexibility responding to the market dynamics called reconfigurable manufacturing systems (RMS) are required by market according to manufacturing experts. The manufacturing systems with modular architecture are the best way to meet flexible and adaptable RMSs because they allow reconfiguration by a simple module substitution or by resetting module operation parameters. This paper presents a design methodology developed to obtain modular RMS. The method integrates the utilization of modular architecture principles, selection algorithms (analytical hierarchical process), clustering algorithms (average linkage clustering algorithm), family product features and functional system analysis in the classical product design process. The methodology proposed allows defining the most adequate modular system architecture and the modular definition of the reconfiguration variables that are needed to reach the flexibility required. A real study case about a heat exchanger assembly machine is presented where this methodology is applied in order to present an evidence of its usefulness.     

Digital storytelling in Bhutan: A qualitative examination of new media tools used to bridge the digital divide in a rural community school

This qualitative study examines the use of digital storytelling as an instructional intervention for bridging the digital divide among public school students in rural Bhutan. Primary participants for the study included elementary school children who had never been previously exposed to computer technology and were recipients of a donated classroom set of laptops. Results demonstrated how technology instruction and infrastructure inherently positions ethical and cultural differences between researchers, education personnel, school children and their families. The use of English became an inadvertent gatekeeper for who was chosen to participate in the classroom laptop program. Another major finding examines how Bhutan’s social awareness for “Gross National Happiness” is inherently juxtaposed in contrast to Western perceptions of modernity and progress. Educators and administrators concerned about initial technology instruction in developing regions should find this study informative.     

High temperature high dose C ion implantation in epitaxial SiGe

Si_{1 − x}Ge_x epitaxial layers fully strained (x = 0.27) and relaxed (x = 0.55) have been implanted with C ions at 500°C. Implantation energy and doses were selected to obtain the C peak in the central region of the SiGe layer, with a concentration similar to the Ge content. The implanted layers have been analyzed by Raman scattering, X-ray diffraction, transmission electron microscopy and secondary ion mass spectroscopy. The data obtained show the direct synthesis of β-SiC precipitates aligned in relation to the SiGe lattice after the implantation, as well as a Ge enrichment and stress relaxation of the SiGe lattice. For the relaxed layer a significant Ge redistribution from the implanted region is observed.     

Evaluation of Diluted and Undiluted Trickle-Bed Hydrotreating Reactor with Different Catalyst Volume

In this work, a comparative study on the combined effects of hydrodynamics and kinetics on the hydrodesulfurization (HDS) of a straight-run gas oil (SRGO) using a trickle-bed reactor with and without diluent (SiC) and different catalyst volume (0.1, 0.07, and 0.050 × 10^-3 m³, respectively) was carried out. The tests were conducted in a pilot plant under conditions close to those used in industrial-scale units (5492 kPa, 445.4 m³(STP)/m³ H₂/oil ratio, 623-643K, 0.9 and 2.5 h^-1 LHSV values). The catalyst used was a commercial CoMoP/Al₂O₃ formulation shaped as tri-lobed extrudates (1/20 in, nominal size) or as crushed particles (d_p = 1.2 × 10^-3 m). Contrarily to that usually claimed, the undiluted systems showed better performance than those comprising small diluent (SiC) particles (d_p ~ 5 × 10^-5 m). Calculations to evaluate hydrodynamic variables (plug-flow behavior, wall effects, wetting, and back-mixing) were carried out in order to explain the observed facts. The possible influences of the size of the diluent particles used are discussed.     

Chagas disease: impact of Triatoma infestans control program in Alto del Carmen, Huasco Province, III Region Atacama, Chile

A control program of Triatoma infestans has been carried out in Alto del Carmen, an endemic chagasic rural county in the III Region, Chile. The program started in 1988 with an attack phase consisting in a masshouse spraying with residual insecticide, followed by an entomological surveillance phase with health education for community participation and vector detection in eventually reinfested houses. A yearly evaluation in 1992, 1993, 1994 and 1995 was carried out in order to determine the effectiveness of vector control activities. In 1992, 24.1% of dwellings was infested, whereas in 1993, 1994 and 1995 the infestation rates were 3.9%, 2.8% and 4.0% respectively. The similar infestation rates found in 1993, 1994 and 1995 suggest passive dispersion of triatomas from areas without surveillance. Additionally, in 1994, 110 (16.0%) out of 688 examined people resulted serologically positive. It is noteworthy that all of the children in the 0-4 year age group--born after the attack phase--resulted serologically negative. This fact may indicate the interruption of vectorial transmission of Chagas' disease in Alto del Carmen county. It is concluded that the control activities performed in the county constitute good strategies to the Nacional Program of Control of T. infestans, but for the success of such a program it is necessary to integrate the efforts of all endemic areas with an active community participation.