Synthesis and design of waveguide band-stop filters without out-of-band spurious responses for plasma diagnosis

Band-stop or notch filters play a crucial role in plasma diagnosis systems to protect receivers from the stray radiation. In this work, a rigorous design process based on circuit synthesis in addition to an extremely compact E-plane waveguide structure is proposed for this kind of filters. On the one hand, the transfer function verifying the rejection specification is analytically obtained, fixing the minimum number of required cavities. On the other hand, a coupling structure that reduces drastically the unwanted resonances in filters with a very large pass band requirement, is presented. This coupling between the rejection cavities and the main rectangular waveguide has additional advantages; (a) unlike typical inductive irises, large coupling coefficients can be implemented (b) a pure E-plane configuration is achieved, which simplifies the manufacturing and also reduces significantly the computational effort. Experimental validation is demonstrated by two pseudo-elliptic fifth-order band-stop filters fabricated and measured in Ka and V bands. In both cases, the filters are free of spurious resonances in their total operation bands.     

Experimental study of lateral pass width in conventional and vibrations-assisted ball burnishing

Burnishing is a mechanical finishing operation performed on workpieces to enhance their surface quality through plastic deformation. One of the main issues to understand the overall process is the behavior of the elastoplastic deformations caused by the burnishing ball on the workpiece. The first burnishing passes performed on the workpiece surface lead to its plastic strain and self-hardening, thus influencing the results of consecutive passes. Some references have studied the phenomenon of indentation, finding that there is a certain self-hardening coefficient threshold which allows to predict the presence of pile-ups at the edges of the indentation path. Nevertheless, burnishing is not a single-pass operation. On the contrary, burnishing a whole surface requires successive adjacent and/or overlapping passes, i.e., parallel passes separated consecutively a certain lateral pass width. No reference has been found in the literature defining the adequate values of the lateral pass width with regards to the pile-up effect to enhance the final topology of the burnished surface. This paper explores that influence by studying the presence of the pile-up effect after burnishing a single or several overlapping passes on two materials (aluminum and steel), by characterizing the topology of the generated path. Afterwards, two adjacent passes are performed, varying the lateral pass width, to compare the final surface roughness derived from each operation. An optimum value for the lateral pass width was found, to improve the final roughness after burnishing in different conditions and to increase the productivity of the process.     

An Antiaphrodisiac in Heliconius melpomene Butterflies

Gilbert (1976) suggested that male-contributed odors of mated females of Heliconius erato could enforce monogamy. We investigated the pheromone system of a relative, Heliconius melpomene, using chemical analysis, behavioral experiments, and feeding experiments with labeled biosynthetic pheromone precursors. The abdominal scent glands of males contained a complex odor bouquet, consisting of the volatile compound (E)-β-ocimene together with some trace components and a less volatile matrix made up predominately of esters of common C₁₆- and C₁₈-fatty acids with the alcohols ethanol, 2-propanol, 1-butanol, isobutanol, 1-hexanol, and (Z)-3-hexenol. This bouquet is formed during the first days after eclosion, and transferred during copulation to the females. Virgin female scent glands do not contain these compounds. The transfer of ocimene and the esters was shown by analysis of butterflies of both sexes before and after copulation. Additional proof was obtained by males fed with labeled D-¹³C₆– glucose. They produced ¹³C-labeled ocimene and transferred it to females during copulation. Behavioral tests with ocimene applied to unmated females showed its repellency to males. The esters did not show such activity, but they moderated the evaporation rate of ocimene. Our investigation showed that β-ocimene is an antiaphrodisiac pheromone of H. melpomene.     

Comparative study of the effect of sulfur on the morphology and rheological properties of SB‐ and SBS‐modified asphalt

The modification of asphalt with styrene‐ butadiene block copolymers and sulfur was studied to elucidate the effect of the molecular characteristics of the polymer, polymer content, and sulfur/polymer ratio on the physical properties of modified asphalts. Two types of styrene‐butadiene copolymers were used (SB and SBS), which differed considerably in terms of their chain architecture, average molecular weights, and size and distribution of their polybutadiene and polystyrene blocks, as shown by gel permeation chromatography, infrared spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. Sulfur/polymer/asphalt blends were prepared by a hot mixing process and characterized by conventional tests, fluorescence microscopy, and rheology. The results revealed that the morphology of the blends is strongly dependent on polymer concentration and sulfur/polymer ratio. In‐depth rheological characterization showed that the thermomechanical properties changed considerably upon addition of small amounts of sulfur. Collectively, these results suggest that sulfur increases the compatibility between polymer and asphalt by crosslinking polymer chains. Interestingly, the rheological behavior of blends prepared with a combination of SB and sulfur was similar to that exhibited by blends prepared with SBS either in the presence or absence of sulfur. This is explained by assuming that the addition of small amounts of sulfur to SB‐modified asphalt facilitates the formation of an elastomeric network that resembles the one found in SBS‐modified asphalt, effectively contributing to asphalt reinforcement. Nonetheless, the exact dosage of sulfur must be carefully controlled to prevent gel formation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The Metabolic Impact of Two Different Parenteral Nutrition Lipid Emulsions in Children after Hematopoietic Stem Cell Transplantation: A Lipidomics Investigation

Hematopoietic stem cell transplantation (HSCT) involves the infusion of either bone marrow or blood cells preceded by toxic chemotherapy. However, there is little knowledge about the clinical benefits of parenteral nutrition (PN) in patients receiving high-dose chemotherapy during HSCT. We investigated the lipidomic profile of plasma and the targeted fatty acid profiles of plasma and erythrocytes in children after HSCT using PN with either a fish oil-based lipid emulsion or a classic soybean oil emulsion. An untargeted liquid chromatography high-resolution mass spectrometry platform connected with a novel in silico annotation algorithm was utilized to determine the most relevant chemical subclasses affected. In addition, we explored the interrelation between the lipidomics profile in plasma, the targeted fatty acid profile in plasma and erythrocytes, several biomarkers of inflammation, and antioxidant defense using an innovative data integration analysis based on Latent Components. We observed that the fish oil-based lipid emulsion had an impact in several lipid subclasses, mainly glycerophosphocholines (PC), glycerophosphoserines (PS), glycerophosphoethanolamines (PE), oxidized PE (O-PE), 1-alkyl,2-acyl PS, lysophosphatidylethanolamines (LPE), oxidized PS (O-PS) and dicarboxylic acids. In contrast, the classic soybean oil emulsion did not. Several connections across the different blocks of data were found and aid in interpreting the impact of the lipid emulsions on metabolic health.     

Thermally stimulated conductivity of Cu3BiS3 thin films deposited by co-evaporation: determination of trap parameters related to defects in the gap

Cu₃BiS₃ thin films were produced by evaporating precursor Cu and Bi species in sulfur atmosphere through a two-stage process. Thermally stimulated current (TSC) measurements were carried out on as-grown Cu₃BiS₃ crystals in the temperature range of 150–400 K. The measurements were performed while increasing temperature at a rate of 5 K/min. Analysis of thermal power measurements at room temperature enabled the type of conductivity of the material, respectively. The spectra obtained from the TSC showed the presence of trapping centers associated with the peaks in the current curves as a function of temperature. Transport mechanisms as hopping and thermally active carriers were identified for low- and high-temperature regions, respectively. Three trapping levels around 1.04 eV were detected from the TSC spectra. These levels in Cu₃BiS₃ crystals may be associated to the presence of structural defects and unintentional impurities during preparation processes. The trap parameters were determined by various analysis methods, and they agree well with each other. A correlation between electrical properties and defects in the material were also studied.     

A device for measuring the angular distribution of incident radiation on tubular solar collectors

The calculation of the incident solar radiation falling upon tubular collectors presents difficulties which do not exist when this is carried out for flat plate collectors. Due to their cylindrical shape, the solar incident radiation on their surface is a function of angle and time. This paper presents experimental results which were obtained by means of a device specially designed in order to measure the distribution of such radiation. The device's sensor element (a photodiode) was characterised, calibrated and subsequently used to measure the angular distribution of radiation incident on the inside surface of the inner tube of an evacuated solar collector. It was found that the experimentally measured distribution agrees with that obtained by the ray-tracing method which appears in the literature.     

Conical receiver for a paraboloidal concentrator with large rim angle

The design and optimization of novel type of receiver for a paraboloidal concentrator with 90° rim angle is carried out by means of detailed ray tracing simulations. Cylindrical, conical, and spherical geometries are compared and their dimensions optimized. The chosen design is based on a conical cavity, which differs from similar receivers developed for concentrators with smaller rim angles. In particular, the receiver is able to catch concentrated solar energy both on its outer side and on the inner walls. Water flows inside the receiver along the conical geometry, in a double layer configuration. The receiver was built and implemented in a 90° rim angle paraboloidal concentrator. Thermal efficiency of the system is evaluated for different flow rates and inlet temperatures, both in stationary and in transient regimes, and results for fluid temperatures are compared with the results predicted by a thermal model. The time constant is evaluated.     

Influence of the cultivar on the organic acid and sugar composition of potatoes

BACKGROUND: Citric, malic, tartaric, oxalic, ascorbic, aconitic and fumaric acids, and sucrose, fructose and glucose, were determined in ten potato cultivars (Azucena negra, Bonita, Bonita negra, Borralla, Colorada de baga, Mora, Negra, Palmera lagarteada, Peluca blanca and Terrenta) from the Canary Islands in order to differentiate them. The influence of the production zone was also considered. RESULTS: Citric acid and sucrose were the most abundant organic acid and sugar, respectively. There were significant differences in all the analysed sugars and organic acids between the potato cultivars, except for oxalic and malic acids. Differences associated with the production zone were found in the contents of organic acids for some cultivars. Linear discriminant analysis is a useful tool to differentiate the potato samples according to the cultivar and the zone of production. CONCLUSIONS: Seven organic acids (citric, oxalic, malic, tartaric, aconitic, fumaric, and ascorbic acids) were identified and quantified in potatoes. The main sugars (sucrose, glucose and fructose) were also determined. The genetic information of the cultivars determines marked differences in sugars and organic acid contents among the analysed potato cultivars. The soil and climatic conditions affect the organic acid and sugar contents of some potato cultivars. Copyright © 2010 Society of Chemical Industry