Blend Of Hydrocarbons Research Articles

Ant Nestmate and Non-Nestmate Discrimination by a Chemosensory Sensillum

In animal societies, chemical communication plays an important role in conflict and cooperation. For ants, cuticular hydrocarbon (CHC) blends produced by non-nestmates elicit overt aggression. We describe a sensory sensillum on the antennae of the carpenter ant Camponotus japonicus that functions in nestmate discrimination. This sensillum is multiporous and responds only to non-nestmate CHC blends. This suggests a role for a peripheral recognition mechanism in detecting colony-specific chemical signals.

Regulation of cuticular and postpharyngeal hydrocarbons in the slave-making ant Polyergus rufescens: effect of Formica rufibarbis slaves

The purpose of this study was to compare cuticular hydrocarbon profiles of slave-making Polyergus rufescens ants reared alone or with their Formica rufibarbis slaves. Chemical analyses showed that due to the close contacts occurring when the Formica were tending the Polyergus, the synthesis of the cuticular hydrocarbons carried by the slaves was enhanced in the slave-makers. The postpharyngeal hydrocarbon levels increased during the first 15 days of life, whether or not the Polyergus were exposed to Formica. Our findings suggest that Polyergus is able to secrete all components of their cuticular hydrocarbon blend and that none are acquired through contact with Formica. In addition to presenting our experimental evidence, several hypotheses are proposed to explain the synthesis and regulation of hydrocarbon blends borne when these two species cohabitate within a single colony.

Improved energy efficiency for CFC domestic refrigerators retrofitted with ozone-friendly HFC134a/HC refrigerant mixture

Conversion of CFC12 systems to eco-friendly ones will be a major thrust area for refrigeration sector in the near future. As and when an existing CFC (chlorofluorocarbon) system has to be recharged it is advisable to retrofit the system with an eco-friendly energy efficient refrigerant. Presently two potential substitutes, namely, HFC134a and HC blends are available as drop in substitutes for CFC12. HC (hydrocarbon) refrigerants do have inherent problems in respect of flammability. HFC134a is neither flammable nor toxic. But HFCs (hydrofluorocarbons) are not compatible with mineral oil and the oil change is a major issue while retrofitting. The above techno-economic feasibility issue to retrofit the existing CFC12 systems with ozone friendly refrigerant and the energy efficiency of the system are the challenges in the domestic refrigeration sector. In this present work an experimental analysis has been carried out in a 165 l CFC12 household refrigerator retrofitted with eco-friendly refrigerant mixture of HFC134a/HC290/HC600a without changing the mineral oil. Its performance, as well as energy consumption, is compared with the conventional one. As the system has been running successfully for more than 12 months it is also evident that the new mixture is compatible with mineral oil. It has been found that the new mixture could reduce the energy consumption by 4 to 11% and improve the actual COP by 3 to 8% from that of CFC12. The new mixture also showed 3 to 12% improvement in theoretical COP. The overall performance has proved that the new mixture could be an eco-friendly substitute to phase out CFC12.

Cuticular hydrocarbons mediate discrimination of reproductives and nonreproductives in the ant Myrmecia gulosa.

In many species of social insects, the cuticular hydrocarbons of adults vary with both colony identity and individual physiology (oogenesis). Such variations have been shown in some ants and social wasps to function in nestmate recognition, but as yet there is no demonstration of their use by workers to recognize egg layers. We report that in the ant Myrmecia gulosa, workers can discriminate queens and fertile workers from infertile individuals based on distinctive blends of long-chained hydrocarbons present both on the cuticle and in the postpharyngeal gland. The purified hydrocarbon fraction of cuticular extracts from queens elicited high interest in workers, unlike the nonhydrocarbon fraction. However, both fractions were necessary to trigger a response of maximal intensity. In contrast, extracts of mandibular and Dufour glands from queens or infertile workers were not treated differentially by workers. We suggest that cuticular hydrocarbons function as pheromones allowing for recognition of the queen as well as egg-laying workers.

Polyolefin Miscibility: Solid-State NMR Investigation of Phase Behavior in Saturated Hydrocarbon Blends

Chain-level mixing in polyolefins is investigated for blends of polyisobutylene (PIB) and polyethylene-co-1-butene (PEB). Previous reports suggest that PIB exhibits unusual mixing behavior in certain saturated blends relative to other polyolefins, even though it is immiscible with most. Variable-temperature 1H, 2H, 13C, and 129Xe NMR experiments are used to characterize local PIB chain dynamics in blends with PEB in which the concentration of 1-butene comonomer units is 23 or 66 wt %. Results from 1D and 2D solid-state 13C exchange experiments, 1H relaxation measurements, and 2H line shape analysis indicate that local conformational dynamics of the PIB CH2 group in the polymer backbone increase significantly in blends with PEB copolymers containing 66 wt % butene comonomer (PEB-66). Even though the PEB-66 is a higher Tg polymer than PIB, PIB exhibits a lower effective Tg when the blend is formed relative to its pure state. Similar perturbations are not observed in the PIB/PEB-23 blend, indicating that this blend is not miscible at the chain level. These results are directly relevant to the length scale of glass transitions in polyolefins, indicating that local interchain packing plays an important role in the conformational dynamics that occur within a chain, and are suggestive of local configurational entropy contributions to mixing. Although 1H spin-diffusion experiments could not reveal quantitative length scales of mixing in the these blends due to insufficient contrast between the constituents, 129Xe NMR experiments showed that the PIB/PEB-66 blend was homogeneous on a 50 nm length scale. In agreement with the heterogeneous morphology indicated by the dynamic NMR experiments, 129Xe NMR showed two resolved peaks for the PIB/PEB-23 blend, indicative of phase separation on a 50 nm length scale. The compilation of all the data, most of which was obtained at natural abundance, indicates that the PIB/PEB-66 blend exhibits intimate chain-level mixing on a length scale much shorter than Rg (ca. 8 nm). More importantly, the data show that reduced chain packing constraints occur in the miscible blend and suggest that local entropic contributions are the driving force for miscibility.

Ketone components in the contact sex pheromone of the white‐spotted longicorn beetle, Anoplophora malasiaca, and pheromonal activity of synthetic ketones

AbstractTwo active fractions were found during the isolation of contact sex pheromone of female elytra of the white‐spotted longicorn beetle, Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae), in addition to fraction of hydrocarbons that had previously been identified. One fraction was essential to evoke a series of precopulatory behaviors of males toward a glass dummy when coated together with the hydrocarbon blend. The other fraction enhanced this activity when added to the mixture. From the latter synergistic fraction, we isolated five novel compounds and identified them as 10‐heptacosanone, (Z)‐18‐heptacosen‐10‐one, (18Z,21Z)‐heptacosa‐18,21‐dien‐10‐one, (18Z,21Z,24Z)‐heptacosa‐18,21,24‐trien‐10‐one, and 12‐heptacosanone by GC‐MS and NMR analyses. A blend of four of these synthetic ketones, without 12‐heptacosanone, in the ratio and concentration found in female elytra extract (250 : 400 : 1000 : 180 ng FE−1) showed greater synergistic effect than the natural fraction containing the ketones. This effect was canceled out by further addition of 12‐heptacosanone (100 ng FE−1), which was still comparable to the effect of the natural ketone fraction.

Transitions in cuticular composition across a hybrid zone: historical accident or environmental adaptation?

Two subspecies of the grasshopper Chorthippus parallelus form a hybrid zone in the Pyrenees. Transitions across the zone, including changes in mating signals and reproductive isolation have been intensively studied. Cuticular pheromones have been identified as likely mate recognition signals. Since the major role of the cuticle is in waterproofing, environmental adaptation of cuticular composition has the interesting potential to generate assortative mating as an incidental by-product. We describe the pattern of variation in cuticular hydrocarbon blend in four transects through the hybrid zone. We find no evidence for a previously observed displaced cline in one blend component. There were differences between subspecies but these varied among transects and were small compared with variation between transects. We examined environmental variation within one transect and found a correlation between vegetation and cuticular composition, suggesting that environment influences the constitution of the cuticle, and hence natural selection may interact with mating signals in this species. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 78, 193−201.

Recent Advances in Sex Pheromone Studies on the White-Spotted Longicorn Beetle, Anoplophora malasiaca

Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae) male approached the female, touched her with his antennae or tarsi, and then held and mounted her by touching her elytra and pronotum with his palpae. Similar mating attempts by males were confirmed on a glass dummy treated with the solvent extract of female elytra, indicating the presence of a female sex pheromone perceptible by direct contact. When the extract was chromatographed on silica gel, only the hexane fraction showed a weak activity. The activity was apparently enhanced when polar fractions were subsequently mixed with this fraction Therefore, the sex pheromone consisted of hydrocarbons and polar compounds that operated synergistically. Among more than 40 hydrocarbons identified by GC-MS analysis, only saturated hydrocarbons induced the mating behavior in males. When 8 major authentic hydrocarbons were mixed together with the polar compounds, the blend induced a series of precopulative behaviors in males. Thus, these hydrocarbons were considered to be the components of the sex pheromone in this beetle. Sexual dimorphism was observed in the hydrocarbon profiles. Some hydrocarbons were common between the sexes while others were sexually specific. A blend of male hydrocarbons and female polar components was still active but the opposite combination was inactive. Therefore, polar female-specific components were critical for revealing the sex pheromonal activity.

Positive genetic correlation between female preference and offspring fitness.

In many species, females display preferences for extreme male signal traits, but it has not been determined if such preferences evolve as a consequence of females gaining genetic benefits from exercising choice. If females prefer extreme male traits because they indicate male genetic quality that will enhance the fitness of offspring, a genetic correlation will evolve between female preference genes and genes that confer offspring fitness. We show that females of Drosophila serrata prefer extreme male cuticular hydrocarbon (CHC) blends, and that this preference affects offspring fitness. Female preference is positively genetically correlated with offspring fitness, indicating that females have gained genetic benefits from their choice of males. Despite male CHCs experiencing strong sexual selection, the genes underlying attractive CHCs also conferred lower offspring fitness, suggesting a balance between sexual selection and natural selection may have been reached in this population.

Worker rank, reproductive status and cuticular hydrocarbon signature in the ant, Pachycondyla cf. inversa

Workers in de-queened colonies of the neotropical ant, Pachycondyla cf. inversa, form linear or near-linear dominance hierarchies by violent antennation and biting. In these rank orders, social status and ovarian activity are on average highly correlated. Whereas the presence of a fertile queen appears to be sufficient to prevent workers from laying eggs, fertile workers do not completely control reproduction by their nestmates, suggesting that workers are able to differentiate between an egg-laying queen and an egg-laying worker. Here we show that the composition of cuticular hydrocarbons of egg-laying workers is quantitatively and qualitatively different from that of non-laying workers and resembles the hydrocarbon blend of the queen but does not completely match it. Furthermore, using discriminant analysis, it was possible to distinguish workers with four different classes of ovarian development based only on their cuticular hydrocarbon profiles. Fertility-associated changes in cuticular hydrocarbons may play an important role in the behavioural regulation of reproduction in this ant.

Inert hydrocarbon-based refrigerants

This paper determines the flammability properties of two hydrocarbon blends, natural gas and propane–butane refrigerant, mixed with CF 3I and C 3F 7 H inerting agents. Four flammability envelopes are obtained allowing the determination of the minimum inerting concentrations and the maximum hydrocarbon to suppressant weight ratios for formulating non-flammable hydrocarbon refrigerants. These ratios are calculated from the slopes of lines drawn from the origin and tangent to the lower branches of the flammability envelopes. The flammability measurements are conducted using a tubular flow burner. The apparatus is convenient to operate, yields reproducible results without repetitive testing necessitated by explosion vessels. More importantly, the tubular flow burner applies a clear criterion for extinction avoiding the innate problems of the explosion vessels, which relate to the strength of the ignition source and the vessel size. The results indicate that it is not possible, using CF 3I or C 3F 7 H, to formulate a refrigerant mixture with a substantial hydrocarbon content. Specifically, inertion of the propane–butane blend considered in this study demands 87.7% and 94.2% by weight of CF 3I and C 3F 7 H, respectively. CF 3I displays similar inerting properties to those of CF 3Br. The higher inerting requirement for C 3F 7 H stems from the nature of this agent to decrease the lower flammability limit of the hydrocarbon blends.

The front basitarsal brush in Pachycondyla apicalis and its role in hydrocarbon circulation

Worker postpharyngeal gland (PPG) chemistry of Pachycondyla apicalis constitutes a blend of hydrocarbons including alkanes, alkenes, and alkadienes, with 5,9-pentacosadiene, 5,9-heptacosadiene and 5,9-nonacosadiene as the major products as well as fatty acids. There is a large congruency between the PPG and cuticular hydrocarbons, however the latter had higher proportion of tricosane and pentacosane, but only traces of fatty acids. These ants have a well-developed cuticular hair brush on the front legs that they frequently pass through the mouth while grooming. Since these brushes have higher amounts of hydrocarbons than either the middle or hind legs, we hypothesized that they are involved in hydrocarbon circulation. We assessed the role of the front basitarsal brush in hydrocarbon circulation by isolating them from the buccal cavity, either by restraining the front legs or by blocking the mouth with glue. In both experiments, preventing contacts between the basitarsal brushes and the mouth for 24 hrs resulted in a considerable increase in hydrocarbon amounts in the brushes with a parallel decrease in the PPG. When the ants were kept alive for an additional 24 hrs after their legs were freed, hydrocarbon amounts in both the PPG and the front legs returned to normal. Analyses of crop content revealed the same hydrocarbons profile as in the PPG, but their amounts were very variable and there were no differences in amounts between the treatment and the control. We assume that part of the PPG hydrocarbons are cleared via the alimentary canal. Grooming behavior of ants restrained for 24 hrs and then freed was followed for four hours thereafter. There was a significant increase in total grooming during the first third and fourth hour, but not during the second. Grooming involving the front legs-mouth, and front legs-antennae, and the front and hind legs was especially intensive during the first hour. Grooming involving the hind legs – body was more intensive in the treated ants during the third hour following their release. We conclude that the front basitarsal brush is a site of hydrocarbon accumulation and that the PPG receives frequent charging during self-grooming.

Glass transition temperatures of hydrocarbon blends: Adhesives measured by differential scanning calorimetry and dynamic mechanical analysis

Glass transition temperatures of hydrocarbon blends: Adhesives measured by differential scanning calorimetry and dynamic mechanical analysis

Thermal diffusivity of rigid polyurethane foams blown with different hydrocarbons

The insulation properties of rigid polyurethane foams are characterized, amongst others, by the heat flow through the solid phase of the foam, which is one of the participants of the heat transfer. Dependence of the thermal diffusivity on the kind of hydrocarbon blowing agent was studied, where 1-dichloro-1-fluoroethane was used as a reference blowing agent. Application of a blend of hydrocarbons, with a boiling point in the range 28–63°C, was found to be particularly advantageous to obtain isotropic foams with satisfactory insulation properties. New environmentally-friendly agents, used for foaming of polyurethane, fulfil a double role. They have an influence on the composition of the gas phase within foam cells, and also on the foam morphology.

Glass transition temperatures of hydrocarbon blends: Adhesives measured by differential scanning calorimetry and dynamic mechanical analysis

A comparison of calculated and measured glass transition temperatures of a series of three-component hydrocarbon blends was performed. The blends were prepared as mixtures of an elastomer with different proportions of tackifying resin and oil. Glass transition temperature, Tg, was measured by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) at four measurement frequencies. Most of these blends had pressure-sensitive adhesive (PSA) properties, and were used to prepare a series of PSA tapes. The adhesion of the PSA tapes was shown to be strongly dependent on Tg. Tack of PSA tapes was measured at two different temperatures, and shown to be directly correlated to the blend Tg. Several predictive methods for blend Tg that are based on individual component Tgs were evaluated. The prediction of blend Tg is far more accurate if the individual component Tg values are determined by DMA instead of DSC. In addition, the Gordon-Taylor equation gave a significant improvement on predicted blend Tg when compared to the Fox equation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 826–832, 2000

Particulate carbon formation from hydrocarbon mixtures

Abstract Particulate carbon (soot) formation during near isothermal pyrolysis of some aromatic hydrocarbon mixtures diluted in helium for nominal temperature of 1473 K was investigated. An inhibition of soot particle formation takes place during pyrolysis of the model hydrocarbon mixtures. As a result, the mixture when pyrolyzed yields coarse soot compared with that produced during pyrolysis of the pure components. The Bureau of Mines Correlation Index (BMCI), hitherto having been a setting parameter for selection of the hydrocarbon mixture for carbon black production, does not take into account an inhibition effect of soot particle nucleation occurring during pyrolysis of hydrocarbon blends. The BMCI specifies the hydrocarbon mixture aromaticity level, that is the C/H ratio rather than a sooting tendency of the mixture and should not be used as a principal criterion in selection of the applicable feedstock for carbon black production. During pyrolysis of hydrocarbon mixtures containing acetylene, it was demonstrated that only acetylene generates soot particle nuclei, whereas the other components are consumed by heterogeneous growth of the particles. This observation might be considered as an experimental evidence contradicting the mechanism of soot formation through a PAH generation stage under conditions of the flat flame combustion.

Comparison of Technology and New Developments with Hydrocarbon Blown Rigid Foams Shows a Clear Tendency to Cyclopentane/ Hydrocarbon Blends

Comparison of Technology and New Developments with Hydrocarbon Blown Rigid Foams Shows a Clear Tendency to Cyclopentane/ Hydrocarbon Blends

Cuticular hydrocarbons of termites of the Hawaiian Islands.

Seven species of termites (Isoptera) belonging to three families are found in the Hawaiian Islands. The Kalotermitidae include Neotermes connexus Snyder, Cryptotermes brevis (Walker), Cryptotermes cynocephalus Light, Incisitermes immigrans Snyder, and the recently introduced Incisitermes minor (Hagen). Zootermopsis angusticollis (Hagen), a native of the Pacific Coastal region of North America has become established on Maui and is the sole representative of the Termopsidae. The only rhinotermitid known to be established in the Hawaiian Islands is Coptotermes formosanus Shiraki. A closely related species, Coptotermes vastator Light, has been reported from the Hawaiian Islands, but not recently documented. Cuticular hydrocarbon mixtures were characterized for each of the established and introduced species, as well as for C. vastator from Guam. The diversity of the hydrocarbon mixtures was extreme. At least half the hydrocarbons of C. brevis, C. cynocephalus, I. immigrans, and N. connexus are olefins. C. formosanus and C. vastator make no olefins, but methyl-branched alkanes comprise ca. 95% and 85% of their hydrocarbon mixtures, respectively. Blends of abundant hydrocarbons are species-specific and can be used to identify a given taxon without the diagnostic castes, soldiers, or imagoes. Cuticular hydrocarbon mixtures appear to correlate with habitat requirements.

Comparison of Technology and New Developments with Hydrocarbon Blown Rigid Foams Shows a Clear Tendency to Cyclopentane/Hydrocarbon Blends

Rigid foams blown with hydrocarbons have shown a great progress since this technology was implemented in 1992 in Europe, and culminated, last year, in the introduction of blends of hydrocarbons and more particularly cyclopentane/isobutane. Also recently, other blends have found favor where the more complicated handling of butane may present some difficulties. In the hydrocarbon family, cyclopentane is the best option in terms of gas k-factor, but its high boiling point requires higher density and shot weights in cabinets to guarantee long term dimensional stability. The best cost option is provided by the iso-/n-pentane blend. However, the foams produced show inferior k-factor, although final energy consumption is not affected to the same degree. In general, the addition of another co-blowing hydrocarbon such as isobutane, isopentane or c-pentane negatively affects the insulation performance of the foam, but recent polyurethane system developments have allowed the retention of the same k-factor values as those of pure cyclopentane blown foams. This paper aims to compare the different hydrocarbon blowing agent alternatives introduced during the past period and includes theoretical cell gas modeling, creep performance and compressive strength ageing tests. These methods have been used to evaluate and predict, during the foam development phase, the short and long term dimensional stability of the foam. An attempt will be made to understand if the combination of all of them is necessary for getting reliable information. Results from cabinets foamed with these cyclopentane based hydrocarbon blends have confirmed the initial findings and are discussed. It is a further objective of this paper to give the OEMs the data that they require to select the optimum technology to answer their needs in terms of cost, processing performance and insulation value.

Mate recognition in the two-spot ladybird beetle, Adalia bipunctata: role of chemical and behavioural cues

On encountering a mature female, a male of the two-spot ladybird, Adalia bipunctata (L.), first palpated her elytra with his maxillary palps, then mounted her, extruded his penis and mated. Copulation never occurred between active males but males copulated with dummies bearing male elytra as frequently as with dummies with female elytra of their own species. Similarly, males attempted mating with immobilised conspecifics of both sexes. However elytra washed in chloroform failed to stimulate mating. Analysis of the chloroform extracts of the elytra revealed that male and female ladybirds are coated by the same blend of hydrocarbons among which 9- and 7-methyl tricosane are dominant. Our results are consistent with a role of these cuticulars hydrocarbons in species recognition and show that behaviour, in particular movement, is necessary for discrimination between males and females.