Influence of extraction method and storage conditions on the volatile oil of wormwood (Artemisia absinthium L.)

 In order to determine the best extraction procedure for volatile oil composition studies in wormwood (Artemisia absinthium L.), several extraction techniques have been investigated. In pentane extracts obtained using microwave or ultrasound sources of radiation, no thermic degradations occurred, but high amounts of heavy oils and waxes resulted, causing trouble in the gas chromatographic analysis. Headspace extraction provided the most volatile constituents, but high molecular weight compounds were not extracted. Simultaneous distillation-extraction resulted in the most adequate extraction procedure for volatile oil composition studies since the required compounds were extracted with minimum degradations when the distillation time was no longer than 30 min. Freezing and drying processes did not greatly affect the percentage composition of wormwood volatile oil. Received: 29 June 1998 / Revised version: 8 October 1998     

Land prices and housing prices: the case of Spain

This research analyzes the Granger causality relation between land and housing prices in Spain. This relation is examined using Spanish provincial quarterly observations for the period 2005Q1–2010Q2. The results show that there is a bidirectional relationship between both markets. However, while the causality from the housing market to the land market is clear, the causality in the opposite direction, although statistically significant, is much weaker.     

Highly accurate 5-axis flank CNC machining with conical tools

A new method for 5-axis flank computer numerically controlled (CNC) machining is proposed. A set of tappered ball-end-mill tools (aka conical milling tools) is given as the input and the flank milling paths within user-defined tolerance are returned. Thespace of lines that admit tangential motion of an associated truncated cone along a general, doubly curved, free-form surface is explored. These lines serve as discrete positions of conical axes in 3D space. Spline surface fitting is used to generate a ruled surface that represents a single continuous sweep of a rigid conical milling tool. An optimization-based approach is then applied to globally minimize the error between the design surface and the conical envelope. The milling simulations are validated with physical experiments on two benchmark industrial datasets, reducing significantly the execution times while preserving or even reducing the milling error when compared to the state-of-the-art industrial software.     

Biolubricants and triboreactive materials for automotive applications

The research institution TEKNIKER has coordinated the EUROPEAN Project EREBIO, were different biodegradable lubricants have been formulated by FUCHS and BAM for heavy duty engines (GUASCOR), and passenger cars (RENAULT). In the frame of this article, it has been summarised the results obtained when developing biodegradable passenger car lubricants in combination with triboreactive materials.Replacing hydrocarbon-based oils with biodegradable products is one of the ways to reduce adverse effects on the ecosystem caused by the use of lubricants. The application of low or no sulphur, ash and phosphorous (lowSAP) ester- or polyglycol-based oils, intended for passenger car engine lubricants as substitutes for hydrocarbon-based oils, required the preparation of a composition of lubricants with comparable tribological and functional properties.The study is focussed on passenger car motor oils (PCMO) with reduced metal-organic additives. This is necessary in order to reduce the ash build-up in the after treatment system and therefore improve its efficiency and lifetime. High fuel efficiency and long drain intervals are requested, as well. To follow a line in a consequent way, these oils have to be biodegradable and non-toxic to the aqueous environment according to the directive EC/1999/45, coherent with other international standard. In a modern diesel or gasoline engine, the engine oils has to fulfil quite a number of different functions, such as lubricating and cooling the system, wear protection, soot and particle handling with less deposit tendency and so on.In the paper a study of the biodegradability, toxicity and the tribological properties has been carried out for new developed prototype engine bio-oils. Also, some different plasma sprayed triboreactive coatings have been deposited on cast iron piston rings, being studied also their tribological properties. Finally, the behaviour of the new bio-oils selected and plasma sprayed triboreactive coatings on piston rings have been screened in a real engine.     

The Role of Adsorbed and Subsurface Carbon Species for the Selective Alkyne Hydrogenation Over a Pd-Black Catalyst: An <Emphasis Type="Italic">Operando</Emphasis> Study of Bulk and Surface

The selective hydrogenation of propyne over a Pd-black model catalyst was investigated under operando conditions at 1 bar making use of advanced X-ray diffraction (bulk sensitive) and photo-electron spectroscopy (surface sensitive) techniques. It was found that the population of subsurface species controls the selective catalytic semi-hydrogenation of propyne to propylene due to the formation of surface and near-surface PdC_x that inhibits the participation of more reactive bulk hydrogen in the hydrogenation reaction. However, increasing the partial pressure of hydrogen reduces the population of PdC_x with the concomitant formation of a β-PdH_x phase up to the surface, which is accompanied by a lattice expansion, allowing the participation of more active bulk hydrogen which is responsible for the unselective total alkyne hydrogenation. Therefore, controlling the surface and subsurface catalyst chemistry is crucial to control the selective alkyne semi-hydrogenation.     

Highly sensitive PCR-based detection method specific for Aspergillus flavus in wheat flour

Aspergillus flavus is frequently found in food, producing a wide variety of toxins, aflatoxins being the most relevant in food safety. A specific PCR-based protocol for this species is described which allowed discrimination from other closely related species having different profiles of secondary metabolites from the Aspergillus Section Flavi, particularly A. parasiticus. The specific primers were designed on the multi-copy internal transcribed region of the rDNA unit (ITS1-5.8S-ITS2 rDNA) and were tested in a wide sample of related species and other fungal species commonly found in food. The PCR assay was coupled with a fungal enrichment and a DNA extraction method for wheat flour to enhance the sensitivity of the diagnostic protocol. The results indicated that the critical PCR amplification product was clearly observed for wheat flour contaminated by 10(2) spores after 16 h of incubation.     

Solvent‐free synthesis of glycerol carbonate and glycidol from 3‐chloro‐1,2‐propanediol and potassium (hydrogen) carbonate

BACKGROUND: An indirect solvent‐free synthetic approach for obtaining glycerol carbonate and glycidol from glycerol and CO₂ through their more reactive and easily synthesizable derivatives 3‐chloro‐1,2‐propanediol (HAL) and potassium (hydrogen) carbonate has been studied. RESULTS: The reaction is fast with source of carbonation and temperature having a strong influence on the results. A yield of 80% glycerol carbonate together with a simultaneous substantial production of glycidol (0.56 mol mol^?1 glycerol carbonate) are obtained using K₂CO₃ as the carbonation source at 80 °C, a reaction time of 30 min and a 3:1 HAL/K₂CO₃ molar ratio. A lower yield of glycerol carbonate (60%) is obtained from KHCO₃ after 50 min with the other experimental conditions remaining unchanged. In this case, glycidol formation is zero or insignificant. Glycerol is also obtained in high yields, although in much lower amounts from KHCO₃ (～0.59 mol mol^?1 glycerol carbonate independent of operating conditions) than from K₂CO₃ (0.84–1.1 mol mol^?1 glycerol carbonate, depending on experimental conditions). CONCLUSIONS: The proposed synthetic strategy overcomes the currently difficult direct reaction between glycerol and CO₂, leading to the simultaneous synthesis of two valuable chemicals: glycerol carbonate and glycidol. However, glycerol is also obtained in substantial amounts thus decreasing the overall yield of the process. Thus, methods for preventing its formation must be developed for industrial feasibility. Copyright © 2010 Society of Chemical Industry     

Characterization of poly (N‐vinyl formamide) by size exclusion chromatography–multiangle light scattering and asymmetric‐flow field‐flow fractionation–multiangle light scattering

The molar mass and the radius of gyration of three poly N‐vinyl formamide (polyNVF) synthesized in aqueous solution polymerization were characterized using two different fractionation techniques: size exclusion chromatography (SEC) and asymmetric‐flow field‐flow fractionation (AF4) coupled with a multiangle light scattering (MALS) and a refractive index (RI) detector. For the sake of comparison, the polymers were also characterized by MALS using the Zimm plot approach (no fractionation). The dn dc^?1 of the poly (N‐vinyl formamide) was measured (0.1564 mL g^?1) and it was found to be insensitive to the molar mass (in the range 150–450 kDa) and also to the eluents used (DDI water or mixed eluent DDI water/acetonitrile (80 : 20) at pH = 5.5). Interestingly, the concentrations of the samples injected in the SEC and AF4 should be different because concentrations in the range of 20–40 mg mL^?1 used for the AF4 caused overloading and anomalous elution in the SEC and hence misleading molar masses. At adequate concentrations in each fractionation equipment, the molar masses were in reasonable good agreement although AF4/MALS provided larger values than the other two techniques likely because samples were not filtered before injection. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42434.