A spectro-microscopic investigation of Fe-Co bimetallic catalysts supported on MgO for the production of thin carbon nanotubes

Fe-Co bimetallic catalysts supported on MgO were studied for the catalytic chemical vapor deposition growth of carbon nanotubes (CNTs). Different wt.% metal loadings were investigated at various deposition temperatures and times. Characterization of the products involved thermal analysis (DTA-TGA), X-ray diffraction, spectroscopy (Raman, UPS, EELS and STS) and microscopy (SEM, TEM and STM) techniques. It was found that the metal content is critical, not only to the yield and the structural quality of the synthesized carbon nanotubes, but it can be also used to tune the desired type of synthesized nanotubes. Lower (2 wt.%) loadings of Fe-Co catalysts favor the formation of single- and/or double-wall CNTs for deposition time and temperature 30 min and 800 °C, respectively. Thermal analysis and Raman measurements showed that these thin CNTs were synthesized at high amounts (CNT-per-catalyst wt.% of more than 100%), exhibiting high graphitization degree with only traces of by-products (mainly amorphous carbon) among them. Microscopy results revealed the formation of CNTs bundles, consisting of individual nanotubes with less than 2 nm outer diameter, while additional energy loss measurements pointed out that the deposited CNTs are mainly single wall. Higher (10 wt.%) Fe-Co loadings resulted to the formation of multi-wall CNTs.     

CFD simulations of segregating fluidized bidisperse mixtures of particles differing in size

In this work, we use a multifluid model to investigate numerically the dynamics of segregating fluidized bidisperse mixtures. The model uses the default multifluid equations of commercial computational fluid dynamics (CFD) codes, except for the fluid–particle drag force closure, which Mazzei and Lettieri [1] recently developed and extended to polydisperse systems. The study also comprises some preliminary simulations of collapsing monodisperse beds, focusing on the role of the plastic solid stress. This work tests whether the model is able to correctly predict not only the axial segregation profiles through the bed, but also the minimum fluid velocities at which a) the mixture, being no longer fixed, starts segregating and transient fluidization takes place, and b) the mixture becomes steadily fluidized and fully mixed. To validate the model predictions, we use the experimental findings of Marzocchella et al. [2]. The plastic stress results to play an important role, rendering the simulations more stable and allowing for larger time steps. The model well predicts the stationary axial segregation profiles, and for short computational times estimates correctly the onset of transient fluidization; for longer computational times, however, the system evolves towards a new steady state where, even if the powder is at maximum packing, it partly segregates. The model overestimates the velocity required to fully mix the suspension, probably because the simulated bubbling is not as vigorous as it is experimentally.     

Effect of different ventilation regimens on ewes' milk and Canestrato Pugliese cheese quality in summer

The influence of three different ventilation regimens on air pollution in sheep houses and on the quality of ewe milk and of Canestrato Pugliese cheese was investigated during the summer season. The experimental treatments were low ventilation regimen (VR=35 m3/h per ewe) split in 30-min ventilation cycles (LOV-30); moderate ventilation regimen (VR=70 m3/h per ewe) split in 30-min ventilation cycles (MOV-30); moderate ventilation regimen (VR=70 m3/h per ewe) split in 60-min ventilation cycles (MOV-60). The LOV-30 milk had higher microbial load and bulk milk somatic cell count (BMSCC) and resulted in a weaker casein matrix in the curd compared with the MOV-30 and MOV-60 treatments. At 45 d of ripening, the LOV-30 cheeses had a lower casein content and higher non-casein nitrogen (NCN) and water-soluble nitrogen (WSN) contents than the MOV-30 and MOV-60 cheeses. Urea-polyacrylamide gel electrophoresis (urea-PAGE) of the pH 4.6-soluble N extract showed that the MOV-60 cheeses had fewer bands derived from casein (CN) hydrolysis than the LOV-30 or MOV-30 cheeses, despite its having exhibited the highest plasmin (PL) activity levels. Our results suggest that the ventilation regimen is critical in dairy sheep housing for optimizing the hygienic quality of ewe milk and the proteolytic processes occurring in Canestrato Pugliese cheese during ripening.     

And then what happened? A retrospective appraisal of China’s Renewable Energy Development Project (REDP)

From 2002 to 2007, more than 400,000 photovoltaic (PV) solar home systems (SHS) were sold in northwestern China under the US$316 million World Bank/Global Environment Facility-supported Renewable Energy Development Project (REDP). REDP has been hailed as a best practice example in SHS deployment for its unprecedented scale and the combination of technology improvement and market development support components to strengthen the country’s renewable energy industry. While the World Bank has itself conducted post-project evaluations, our paper presents the first independent review with the intent of determining if anticipated project impacts have been sustained. We adopt a case study format supported by in-depth interviews with the project’s relevant stakeholder groups and find that solar home systems (SHS) provide monetary and non-monetary benefits to users and that their portability complements the lifestyle of the region’s nomadic herders. However, we also find that purchasing decisions are still based on price more than quality, after-sales service networks remain weak, and households in REDP’s coverage area are gradually gaining access to hydropower-based grid electricity.     

Optimization of a Phenylacetaldehyde-Based Attractant for Common Green Lacewings (<Emphasis Type="Italic">Chrysoperla carnea s.l.</Emphasis>)

In field trapping tests, the catch of Chrysoperla carnea sensu lato (Neuroptera: Chrysopidae) increased when acetic acid was added to lures with phenylacetaldehyde. The addition of methyl salicylate to the binary mixture of phenylacetaldehyde plus acetic acid increased catches even further. The ternary blend proved to be more attractive than β-caryophyllene, 2-phenylethanol, or 3-methyl eugenol (compounds previously described as attractants for chrysopids) on their own, and no influence on catches was recorded when these compounds were added as fourth components to the ternary blend. There were minimal changes in activity when (E)-cinnamaldehyde or methyl anthranylate (both evoking large responses from female or male antennae of C. carnea in this study) were added, although both compounds showed significant attraction on their own when compared to unbaited traps. In subtractive field bioassays with the ternary mixture, it appeared that the presence of either phenylacetaldehyde or methyl salicylate was important, whereas acetic acid was less so in the ternary mixture. The ternary blend attracted both female and male lacewings at sites in southern, central, and northern Europe. Possible applications of a synthetic attractant for lacewings are discussed.     

Rule-based production planning in flexible manufacturing systems

Production planning in flexible manufacturing may require the solution of a large-scale discrete-event dynamic stochastic optimization problem, due to the complexity of the system to be optimized, and to the occurrence of discrete events (new orders and hard failures). The production planning problem is here approached for a multistage multipart-type manufacturing shop, where each work cell can share its processing time among the different types of parts. The solution of this problem is obtained by an open-loop-feedback control strategy, updated each time a new event occurs. At each event time, two coupled problems are solved: 1) a product-order scheduling problem, conditioned on estimated values of the production capacities of all component work cells; and 2) a production-capacity planning problem, conditioned on predefined sequences of the product orders to be processed. In particular, the article aims at defining a production planning procedure that integrates both analytical tools, derived from mathematical programming, and knowledge-based rules, coming from experience. The objective is to formulate a hybrid (knowledge-based/analytical) planning architecture, and to analyze its use for multicell multipart-type manufacturing systems.     

Determining how much info Bob and Alice really need to communicate

This paper describes the two-party communication complexity model. Each message is a string of bits and carried out according to some fixed protocol. Cost of information transfer associated with a given distributed computation is focused in this paper. This paper also presents an overview of basic algebraic and combinatorial tools that has been used in this theory.     

Synthese hydrothermale a tres haute pression de deux borates de type olivine,AlMgBO4 et FeNiBO4

Two borates compounds with olivine type of structure have been prepared by hydrothermal synthesis under high pressure conditions: the mineral sinhalite with the formula AlMgBO₄ and a new dense form of the warwickite type FeNiBO₄. The density of this high pressure phase is about 5% higher than that of the warwickite form. This is the first example of dimorphism in a warwickite type of compound.