Hexanol Concentration Research Articles

Aroma Potential of German Riesling Winegrapes during Late-Stage Ripening

The “aromatic maturity” of winegrapes is not fully understood, particularly during the later stages of ripening. The contribution of grapes to wine aroma has historically been challenging to determine, given most aroma compounds originate from nonvolatile precursors. In this study, an analytical approach previously developed for red winegrapes was adapted to assess the “aroma potential” of Riesling from two vineyards in Essenheim and Durbach, Germany, during the 2022 vintage, by extracting and hydrolyzing aroma precursors in an anoxic model wine matrix. Following sensory and chemical analyses of the hydrolysates using flash profiling and gas chromatography, a multiple factor analysis revealed vineyard- and ripening-dependent changes to aroma, even after total soluble solids had plateaued. As samples matured, green apple and fresh/vegetal aromas were prominent among the Durbach hydrolysates, likely due to persistent concentrations of hexanol. Hydrolysates from both vineyards nonetheless developed more pronounced citrus fruit, tropical fruit, and floral aromas, reflecting increased concentrations of various norisoprenoids and terpenoids. Findings suggest delaying harvest past technological maturity could confer greater aromatic intensity and complexity. The analytical approach used here appears promising for future studies on other grape varieties and other factors that could influence aroma, such as viticultural practices and environmental conditions.

The Composition of Volatiles and the Role of Non-Traditional LOX on Target Metabolites in Virgin Olive Oil from Autochthonous Dalmatian Cultivars.

The lipoxygenase pathway has a significant influence on the composition of the volatile components of virgin olive oil (VOO). In this work, the influence of the maturity index (MI) on the activity of the lipoxygenase enzyme (LOX) in the fruits of the autochthonous Dalmatian olive cultivars Oblica, Levantinka and Lastovka was studied. The analysis of the primary oxidation products of linoleic acid in the studied cultivars showed that LOX synthesises a mixture of 9- and 13-hydroperoxides of octadecenoic acid in a ratio of about 1:2, which makes it a non-traditional plant LOX. By processing the fruits of MI~3, we obtained VOOs with the highest concentration of desirable C6 volatile compounds among the cultivars studied. We confirmed a positive correlation between MI, the enzyme activity LOX and the concentration of hexyl acetate and hexanol in cultivars Oblica and Lastovka, while no positive correlation with hexanol was observed in the cultivar Levantinka. A significant negative correlation was found between total phenolic compounds in VOO and LOX enzyme activity, followed by an increase in the MI of fruits. This article contributes to the selection of the optimal harvest time for the production of VOOs with the desired aromatic properties and to the knowledge of the varietal characteristics of VOOs.

Influence of inclusion of grapevine leaves, rachis and peduncles during fermentation on the flavour and volatile composition ofVitis viniferacv. Shiraz wine

Background and Aims The presence of matter other than grapes (MOG) is common in the winemaking process when sorting equipment is not utilised. Experimental wines were made to examine the effect of MOG on the sensory profile and chemical composition of wine. Methods and Results A Shiraz wine made without MOG was compared to fermentations with grape leaves, grape stalks (rachis) and peduncles (the stalk connecting the bunch to the vine) added at amounts at or slightly above those found in a commercial harvest bin. Fifty-one volatile aroma compounds were quantified in the wines, and sensory descriptive analysis was applied. The wine made with leaves added was rated by the sensory panel similar to the Control and was significantly higher only in positive aromas such as ‘confectionery’ and ‘red fruit’ likely due to a higher concentration of hexanol and (Z)-3-hexen-1-ol. The addition of peduncles slightly enhanced ‘green’ aroma and flavour. The rachis treatment was high in ‘green capsicum/green stalks’ attributes, as well as astringency, and was high in methoxypyrazines. Conclusions The inclusion of different types of MOG during fermentation can alter the sensory profile and chemical composition of Shiraz wines in varying ways, including extraction of methoxypyrazines from the rachis, resulting in notable ‘green’ attributes. Significance of the Study The inclusion of MOG is unavoidable in common winemaking practices, especially with the use of mechanical harvesting. Determining the influence of MOG on the volatile composition of the finished wine is an important step in manipulating wine style.

Saccharomyces bayanus Enhances Volatile Profile of Apple Brandies

Qualitative and quantitative profiles of volatiles in alcoholic beverages depend mainly on the quality of raw materials, yeasts used for fermentation, and processing technique. Saccharomyces bayanus is a yeast species which is not commonly used for the production of alcoholic beverages, but it is able to produce volatiles that add desirable aroma. Since there is little information regarding the application of that microorganism for the production of apple brandies and how it affects volatile profile of finished products, we decided to address that issue. The aim of the study was to determine the impact of S. bayanus on the profile of volatile compounds and sensory properties of apple spirits obtained from three apple cultivars (Topaz, Rubin, and Elise) in comparison to spirits obtained from fermentation carried out spontaneously or with Saccharomyces cerevisiae. Obtained brandies were analysed using gas chromatography–flame ionization detector (GC–FID), solid phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS) and sensorially. In our study, brandies produced from musts fermented by S. bayanus demonstrated the highest concentration of ethyl esters and increased concentrations of isoamyl acetate, 2-phenylethyl acetate, ethyl palmitate and hexanol. Moreover, our results support the hypothesis that non-Saccharomyces yeasts which are present during spontaneous fermentation and demonstrate higher β-glucosidase activities enhance aroma of alcoholic beverages through releasing aroma compounds from glycosidic forms, e.g., α-phellandrene, (E)-β-fanesene, (Z,E)-α-farnesene, α-farnesene, and farnesol. Considering results obtained in sensory analysis, we proved that S. bayanus is suitable for the production of apple brandies, improving their flavour. Brandies obtained from musts fermented by S. bayanus obtained the highest average range for “overall note” parameter in sensory analysis.

Enantioselective esterification of (R,S)-2-(4-methylphenyl) propionic acid via Novozym 435: Optimization and application

This paper reports on the resolution of ( R,S )-2-(4-methylphenyl) propionic acid (MPPA) enantiomers by enzymatic esterification in organic solvent. Novozym 435 (CALB) has the best catalytic performance compared with other lipases. Of the alcohols screened, n -hexanol is the best acyl acceptor and gives the highest enzyme activity and enantioselectivity in n -hexane. Response surface methodology (RSM) was used to evaluate the influence of the factors, such as temperature, enzyme amount, substrate concentration and reaction time on the substrate conversion ( c ) and enantiomeric excess (ee). The correlation coefficient R 2 for enantiomeric excess and the conversion are 0.9827 and 0.9910, respectively, indicating that can accurately predict the experimental results. By simulation and optimization, the optimal conditions were obtained, involving 600 mmol·L −1 MPPA concentration (0.60 mmol), 850 mmol·L −1 hexanol concentration (0.85 mmol), 58 mg enzyme amount, 75 °C temperature and 4.5 h reaction time, respectively. Under the optimized conditions, the experimental values of conversion and enantiomeric excess were 89.34% and 97.84%, respectively, which are in good agreement with the model predictions.

Takes Two to Tango: Choreography of the Coadsorption of CTAB and Hexanol at the Oil-Water Interface.

Mixed surfactant systems at the oil-water interface play a vital role in applications ranging widely from drug delivery to oil-spill remediation. Synergistic mixtures are superior emulsifiers and more effective at modifying surface tension than either component alone. Mixtures of surfactants with dissimilar polar head groups are of particular interest because of the additional degree of control they offer. The interplay of hydrophobic and electrostatic effects in these systems is not well understood, in part because of the difficulty in examining their behavior at the buried oil-water interface where they reside. Here, surface-specific vibrational sum frequency spectroscopy is utilized in combination with surface tensiometry and computational methods to probe the cooperative molecular interactions between a cationic surfactant cetyltrimethylammonium bromide (CTAB) and a nonionic alcohol (1-hexanol) that induce the two initially reluctant surfactants to coadsorb synergistically at the interface. A careful deuteration study of CTAB reveals that hexanol cooperates with CTAB such that both molecules preferentially orient at the interface for sufficiently large enough concentrations of hexanol. This work's methodology is unique and serves as a guide for future explorations of macroscopic properties in these complex systems. Results from this work also provide valuable insights into how interfacial ordering impacts surface tensiometry measurements for nonionic surfactants.

Metabolism of Odorant Molecules in Human Nasal/Oral Cavity Affects the Odorant Perception.

In this study, we examined the mode of metabolism of food odorant molecules in the human nasal/oral cavity in vitro and in vivo. We selected 4 odorants, 2-furfurylthiol (2-FT), hexanal, benzyl acetate, and methyl raspberry ketone, which are potentially important for designing food flavors. In vitro metabolic assays of odorants with saliva/nasal mucus analyzed by gas chromatography mass spectrometry revealed that human saliva and nasal mucus exhibit the following 3 enzymatic activities: (i) methylation of 2-FT into furfuryl methylsulfide (FMS); (ii) reduction of hexanal into hexanol; and (iii) hydrolysis of benzyl acetate into benzyl alcohol. However, (iv) demethylation of methyl raspberry ketone was not observed. Real-time in vivo analysis using proton transfer reaction-mass spectrometry demonstrated that the application of 2-FT and hexanal through 3 different pathways via the nostril or through the mouth generated the metabolites FMS and hexanol within a few seconds. The concentration of FMS and hexanol in the exhaled air was above the perception threshold. A cross-adaptation study based on the activation pattern of human odorant receptors suggested that this metabolism affects odor perception. These results suggest that some odorants in food are metabolized in the human nasal mucus/saliva, and the resulting metabolites are perceived as part of the odor quality of the substrates. Our results help improve the understanding of the mechanism of food odor perception and may enable improved design and development of foods in relation to odor.

Genetic dissection of hexanol content in soybean seed through genome-wide association analysis

Hexanol is a major compound contributing to the off-flavors (the bean-like odor) of soybean derived soymilk. The most effective way to reduce the off-flavors of soymilk is the screening and utilization of soybean cultivars with improved hexanol content. However, no genome-wide genetic analysis for this particular trait has been conducted to date. The objective of the present study was to dissect the genetic basis of hexanol content in soybean seed through genome-wide association analysis (GWAS). A total of 105 soybean accessions were analyzed for hexanol content in a three-year experiments and genotyped by sequencing using the specific locus amplified fragment sequencing (SLAF-seq) approach. A total of 25 724 single nucleotide polymorphisms (SNPs) were obtained with minor allele frequencies (MAF)>5%. GWAS showed that 25 quantitative trait nucleotides (QTNs) were significantly associated with the hexanol concentration in soybean seed. These identified QTNs distributed on different genomic regions of the 15 chromosomes. A total of 91 genes were predicted as candidate genes underlying the seed hexanol level and six candidates were predicted possibly underlying the seed hexanol by gene based association. In this study, GWAS has been proven to be an effective way to dissect the genetic basis of the hexanol concentration in multiple genetic backgrounds. The identified beneficial alleles and candidate genes might be valuable for the improvement of marker-assisted breeding efficiency for low hexanol level and help to explore possible molecular mechanisms underlying hexanol content in soybean seed.

Influence of hexanol as additive with Calophyllum Inophyllum biodiesel for CI engine applications

In the present work, an experiment on ternary blends made of n-hexanol, diesel and Calophyllum Inophyllum methyl ester was conducted to compare the emission, performance and combustion characteristics to that of pure diesel and Calophyllum Inophyllum methyl ester. In the present research work, all the ternary blends were prepared by keeping the diesel weight percentage as a constant at 50% by volume, the Calophyllum Inophyllum methyl ester and hexanol concentrations were varied by volume and the developed blends were used for the comprehensive analysis. The brake thermal efficiency was observed to be significantly higher for the hexanol blends; especially for 40% hexanol is closer to that of pure diesel at elevated brake mean effective pressures. Also, the brake specific fuel consumptions are observed to be lower than that of pure CIME. Emissions such as hydrocarbon, smoke opacity and carbon monoxide were found to be significantly lower than the diesel. However, the NOx and carbon dioxide emissions for alcohol blends remained marginally higher compared to diesel. A significant improvement in the combustion characteristics such as the in-cylinder pressures and net HRR figures were observed when compared to pure biodiesel. Therefore, from the results, it is recommended that the 30% and 40% of n-hexanol blends with further study can suitably be a potential alternative for pure diesel.

Thermoreversible gelation and self-assembly behavior of dibenzylidene sorbitol in ternary solvent mixtures

The self-assembly behavior of 1,3:2,4-dibenzylidene-D-sorbitol (DBS) in ternary solvents has been systematically investigated for the use of kerosene gel in the aerospace propulsion. DBS forms a yield viscoelastic gels in a wide range of kerosene/hexanol/DMSO solvent concentrations despite the fact that DBS is incapable of gelling kerosene fuel. The gelation behavior of DBS in the solvent mixture is predicted using the Hansen solubility parameters. The polar parameter (δP) and hydrogen bonding (δH) parameter lie in the range of 1.96 ≤ δP ≤ 4.30 J0.5cm−1.5 and 3.40 ≤ δH ≤ 7.30 J0.5cm−1.5 respectively for the formation of gel in kerosene/hexanol/DMSO system. The phase transition temperature (Tf) of DBS gel is determined using temperature sweep measurement and predicted using modified Friedrich (MF) relation which is found be in close agreement with an average deviation of ± 10 °C. However, the deviation becomes larger when δP > 4.30 and δH > 7.30, in other words, with increase in the solvent polarity. As the solvent polarity or concentration of hexanol increases in the mixture, the gels exhibit a low Tf and $$ {G}_{max}^{\prime } $$ value because of the hindrance of self-assembling ability of DBS due to the intermolecular hydrogen bonding between DBS and solvents. The viscoelastic behavior of DBS gels is investigated using the oscillation sweep measurements and the storage modulus G′ is found to be higher than the loss modulus G″ for larger stress amplitude and frequency, indicating a solid-like nature of the gels. Furthermore, the microstructure analysis shows the presence of 3D nano-fibrillar morphology, which further depends on the solvent polarity. Microstructure changes from ‘rope-like’ fiber aggregate (Hex100; CH = 88 wt%) to a ‘web-like’ structures (Hex25; CH = 25 wt%), when the CH is decreased in the solvent mixture.

Application of artificial neural network‐based generic model control to multivariable processes

AbstractThe present study focuses on the application of a purely data‐driven artificial neural network (ANN)‐based generic model controller (GMC) for multiple‐input and multiple‐output systems with relative degree one or more. The approach is based on development of an ANN model relating the time‐derivatives of the outputs of the order equal to their relative degree with the past measured values of input and output variables and formulation of a constrained optimization problem to satisfy GMC performance objectives. Two variants of a multivariable semi‐batch reactor (SBR) control problem for esterification reaction of maleic anhydride with hexanol to form hexylmonoester of maleic acid are considered without and with consideration of coolant dynamics (SBR1 and SBR2, respectively). Hexanol concentration and reactor temperature are considered as the outputs, and the coolant and feed flow rates are considered as the manipulated inputs. The present study illustrates that the proposed multivariable ANN‐based GMC exhibits setpoint tracking and disturbance rejection performance similar to the exact model‐based GMC for both the reactors, and the ANN‐based GMC input profiles are smoother and closer to the nominal input profiles compared with GMC controller, although no process information is used other than the output measurements in the proposed approach. © 2017 Curtin University and John Wiley & Sons, Ltd.

Optimization of enzymatic esterification of dihydrocaffeic acid with hexanol in ionic liquid using response surface methodology

BackgroundDeveloping an efficient lipophilization reaction system for phenolic derivatives could enhance their applications in food processing. Low solubility of phenolic acids reduces the efficiency of phenolic derivatives in most benign enzyme solvents. The conversion of phenolic acids through esterification alters their solubility and enhances their use as food antioxidant additives as well as their application in cosmetics.ResultsThis study has shown that lipase-catalyzed esterification of dihydrocaffeic acid with hexanol in ionic liquid (1-butyl-3-methylimidazoliumbis (trifluoromethylsulfonyl) imide) was the best approach for esterification reaction. In order to achieve the maximum yield, the process was optimized by response surface methodology (RSM) based on a five-level and four independent variables such as: dosage of enzyme; hexanol/dihydrocaffeic acid mole ratio; temperature and reaction time. The optimum esterification condition (Y = 84.4%) was predicted to be obtained at temperature of 39.4 °C, time of 77.5 h dosage of enzyme at 41.6% and hexanol/dihydrocaffeic acid mole ratio of 2.1.ConclusionFinally, this study has produced an efficient enzymatic esterification method for the preparation of hexyl dihydrocaffeate in vitro using a lipase in an ionic liquid system. Concentration of hexanol was the most significant (p < 0.05) independent variable that influenced the yield of hexyl dihydrocaffeate.Graphical abstractSynthesis of different Hexyl dihydrocaffeates in ionic liquid

Butanol is cytotoxic to Lactococcus lactis while ethanol and hexanol are cytostatic.

Lactic acid bacteria currently used extensively by the dairy industry have a superior tolerance towards short-chain alcohols, which makes them interesting targets for use in future bio-refineries. The mechanism underlying the alcohol tolerance of lactic acid bacteria has so far received little attention. In the present study, the physiological alcohol stress response of Lactococcus lactis subsp. cremoris MG1363 towards the primary, even-chain alcohols ethanol, butanol and hexanol, was characterized. The alcohol tolerance of L. lactis was found to be comparable to those reported for highly alcohol-resistant lactic acid bacteria. Combined results from alcohol survival rate, live/dead staining, and a novel usage of the β-galactosidase assay, revealed that while high concentrations of ethanol and hexanol were cytostatic to L. lactis, high concentrations of butanol were cytotoxic, causing irreparable damages to the cell membrane.

VOLATILE COMPOUNDS IN GOLDEN DELICIOUS APPLE FRUIT (Malus domestica) DURING COLD STORAGE

Biosynthesis of volatile compounds (VC), as well as activity of related enzymes (lipoxygenase LOX, alcohol acyltransferase AAT, and alcohol dehydrogenase ADH), and fatty acids (palmitic, stearic, oleic, linoleic and linolenic acids) were assessed in Golden Delicious fruit apples (Malus domestica Borkh.) during 1 ºC storage at different atmosphere conditions. Three atmosphere conditions were used: 21 % O2 and &gt; 1 % CO2 (Regular Atmosphere, RA), 3 % CO2 and 2 % O2 (Controlled Atmosphere, CA), and CA, with 7 d under RA conditions (CA + RA), to evaluate the effect of shorts periods under air storage. CA conditions inhibited the production of butyl acetate and hexyl acetate esters, and increased hexanol concentration. Production of the branched ester 2-methyl butyl acetate did not decrease under CA conditions. As a result of 7 d under RA, butyl acetate and hexyl acetate in CA + RA increased, mainly after one month of storage. Storage under CA conditions inhibited LOX and AAT activity at some stages whereas ADH activity increased during CA storage. LOX activity showed high correlation with production of aldehydes (r2 = 0.85) and cis-2-hexenal (r2 = 0.94), during storage of apples under CA conditions. Good correlation was found between AAT activity and total esters and butyl acetate content under CA storage of apples (r2 = 0.92 and r2 = 0.93, respectively). While most fatty acids increased in concentration during RA and CA storage, linolenic acid content decreased. No correlation between volatile compounds content and fatty acid production was found.

Butanol and hexanol production in Clostridium carboxidivorans syngas fermentation: Medium development and culture techniques

Clostridium carboxidivorans was grown on model syngas (CO:H2:CO2 [70:20:10]) in a defined nutrient medium with concentrations of nitrogen, phosphate and trace metals formulated to enhance production of higher alcohols. C. carboxidivorans was successfully grown in a limited defined medium (no yeast extract, no MES buffer and minimal complex chemical inputs) using an improved fermentation protocol. Low partial pressure of CO in the headspace, coupled with restricted mass transfer for CO and H2, was required for successful fermentation. In the absence of substrate inhibition (particularly from CO), growth limitation increased production of alcohols, especially butanol and hexanol. Concentrations of butanol (over 1.0g/L), hexanol (up to 1.0g/L) and ethanol (over 3.0g/L) were achieved in bottle fermentations. Minimal medium and controlled supply of CO and H2 should be used in characterizing candidate butanol and hexanol producing strains to select for commercial potential.

Gross organic phosphorus mineralization rates can be assessed in a Ferralsol using an isotopic dilution method

Mineralization of organic phosphorus (Po) may be of great importance for plant nutrition in soils containing very little available inorganic phosphorus (Pi). Gross organic P mineralization rates can be quantified by an isotopic dilution method using 33P labeling of soil. However, its application remains a challenge in tropical soils in which the concentration of phosphate ions in the soil solution is below the detection limit of traditional colorimetric methods. This limitation can potentially be overcome by the hexanol concentration method, which uses hexanol to concentrate the blue-colored phosphomolybdate complex from large volumes. We applied the isotopic dilution method in combination with the hexanol concentration method to a Ferralsol from the highlands of Madagascar which had been preincubated in the presence or absence of plant residues for 90days before the start of the experiment. The limits of detection (DL) and quantification (QL) of the gross Po mineralization rate were 0.2 and 0.7mgPkg−1soilday−1, respectively. Basal gross Po mineralization rates after 7days of incubation were 0.8±0.5 and 1.7±0.2mgPkg−1soilday−1 in non-amended and residue-amended soils, respectively. These rates are plausible, suggesting that the isotopic dilution method is applicable in highly weathered tropical soils with Pi concentrations in the soil solution below the detection limit of traditional colorimetric methods. Net Po mineralization which sustains the plant available P pool remains to be quantified. Gross and net Po mineralization rates should now be assessed in highly weathered soils under a range of land uses.

Effect of increased irrigation and additional nitrogen fertilisation on the concentration of green aroma compounds inVitis viniferaL. Merlot fruit and wine

Background and Aims Green aroma compounds are considered undesirable when present at a high concentration in red wines. This study aimed to understand the effect of two irrigation levels and a higher than standard nitrogen fertilisation on the concentration of both 3-isobutyl-2-methoxypyrazine (IBMP) and six C6 compounds during fruit development. Methods and Results Fruit samples were collected biweekly during the 2009 and 2010 seasons in a commercial Vitis vinifera L. Merlot vineyard in California, USA, where two irrigation levels (70 and 100% of crop evapotranspiration) and a higher than standard nitrogen fertilisation dose were implemented. The higher irrigation level and additional nitrogen promoted canopy growth and decreased fruit exposure, resulting in increased concentration of IBMP during fruit maturation. The concentration of the six measured C6 compounds, however, was not affected. Deficit irrigation increased fruit colour, quercetin glycosides and phenol-free glucose glycosides (i.e. aroma precursors), and decreased vine yield. The two irrigation levels did not differ on the sensory vegetal perception of the wines, but the additional application of nitrogen fertiliser at fruitset enhanced it. Significance of the Study These findings confirm previous work showing that vineyard management practices influence fruit and wine concentration of IBMP, and demonstrate for the first time that the same practices have no significant impact on the concentration of six C6 compounds in grapes or on the concentration of hexanol in wines. Grapegrowers aiming to minimise IBMP concentration in fruit at harvest would probably benefit from a reduced application of water and nitrogen to the vineyard.

Can the isotopic exchange kinetic method be used in soils with a very low water extractable phosphate content and a high sorbing capacity for phosphate ions?

The isotopic exchange kinetic (IEK) method allows assessing the rate of orthophosphate ions (Pi) exchange between the solid phase and the solution of the soil with time. However, two challenges have to be tackled when using this technique in soils with a very low water extractable Pi concentration (CP) and with a high sorbing capacity for Pi. The first is that current colorimetric methods do not allow quantifying Pi concentrations lower than 10μgP L−1. While the second challenge is that a significant fractionation between P isotopes may occur in the soil solution system in the presence of soils with high Pi sorption capacity. We assessed here: i) whether concentrating the blue phosphomolybdate complex (BPMC) in hexanol prior to its measurement would allow to lower the detection and quantification limits of Pi, ii) whether a significant isotopic fractionation between 32Pi and 33Pi could occur during IEK experiments conducted in the presence of high Pi sorbing substrates (e.g., pure goethite or Malagasy soils) and iii) whether the IEK method when used in conjunction with the hexanol concentration of the BPMC to measure CP would detect changes in Pi isotopic exchangeability in a ferralsol cropped with upland rice following the input of manure or water soluble fertilizer. The detection and quantification limits of the BPMC concentrated by hexanol were 0.3 and 0.8μgPL−1, respectively, using a cell of 10cm length for the colorimetric measurement. The IEK conducted on Pi amended goethite and on Malagasy soils with 32Pi and 33Pi did not show any systematic isotopic fractionation between both isotopes, suggesting that in these soils 31Pi and 32Pi or 33Pi have a similar behavior during isotopic exchange. The analysis of the soils sampled in the field experiment showed a significant increase in the amount of Pi isotopically exchangeable after 1min only after the application of water soluble P. This increase was paralleled by increases in rice yield and P export by grains demonstrating an increased P availability in this treatment. In conclusion, the IEK method can be used in low P and high Pi sorbing soils as the hexanol concentration method allows measuring very low CP and as the different P isotopes have a similar behavior in the soil/solution system. The IEK experiments conducted in the presence of goethite, however, point out to the necessity of taking into account the dispersion of particles for a proper interpretation of the isotopic data.

Granulomes hépatiques pseudo-sarcoidosiques et carcinome hépato-cellulaire : à propos d’un cas et revue de la littérature

Fusarium solani pisi cutinase microencapsulated in reversed micelles of AOT (bis(2-ethylhexyl) sodium sulfosuccinate) was used to catalyse the alcoholysis of butyl acetate (acyl donor) with hexanol. In the present study the stability of cutinase is evaluated comparatively with the initial activity in order to obtain a set of conditions to fully optimise the system. The start conditions were selected based on a synergy of the results assigned in previous work, where relevant parameters for the cutinase activity, such as temperature, buffer molarity, pH, amount of water, surfactant, hexanol and butyl acetate concentrations were studied. Using a 2(5−1) factorial design expanded further to a central composite design (CCD), the effects of each factor mentioned above (with exception of temperature and acetate concentration) on the stability were calculated and the interactions were determined. The surface methodology applied to the results showed that cutinase, incubated at 40°C retained a high activity level (90%) after 3 days when microencapsulated at W0 (molar ratio of water to surfactant) 2.7. The W0 values in the range 5–8 led to optimal-specific activities with lower stability. A hexanol concentration of 500–600 mm was essential to prevent deactivation and at the same time allowed relatively high initial rates. A pH value of 8.0–8.55 and a buffer molarity of 200 mm were suitable for both activity and stability. Cutinase in AOT reversed micelles has been usually reported to be very sensitive to temperature, however, in this work, at an incubation temperature of 40°C, cutinase displayed half-lives significantly greater than previously stated. The main reasons for this are the presence of hexanol and the reduced water content that promote a stabilisation of cutinase structure inside the micelles. The thermostability experiments performed with the selected conditions led to a half-life of 53 days, confirming the model predictions.

Shape controlled synthesis of iron–cobalt alloy magnetic nanoparticles using soft template method

Fe x Co 1 − x alloy nanoparticles of spherical ( x = 0.25, 0.68, 0.85), hollow spherical ( x = 0.60) and sheet like ( x = 0.60) shapes were prepared at room temperature by reduction of iron chloride tetrahydrate and cobalt chloride hexahydrate with sodium borohydride, using N-Cetyl-N,N,N-trimethyl ammonium bromide (CTAB)/water/hexanol system as soft template. The size and shapes of nanostructures were found to depend on the concentrations of CTAB and hexanol in water. Composition and shape dependence of magnetic properties of spherical, hollow spherical and sheet like Fe x Co 1 − x alloy nanostructures were discussed. The highest saturation magnetization of 235 emu/g with a coercivity of 160 Oe was obtained for spherical Fe 0.68Co 0.32 nanoparticles.