Local solid particle behavior inside the upper zone of a circulating fluidized bed riser

The solid phase behavior is studied in the upper zone of a circulating fluidized bed riser with glass particle of mean diameter 107 μm, using a Phase Doppler Anemometer. Superficial gas velocities U_g > U_c are investigated covering the turbulent and the fast fluidization regimes and this for three static bed heights (H_s = 50 mm, H_s = 100 mm and H_s = 150 mm). The results show that the mean axial particle velocity lateral profile shapes found parabolic for H_s = 50 mm, devolve to a concave shape for H_s = 100 mm and H_s = 150 mm, creating a particles speeding zone between the core and the annulus zones. For both axial and transversal standard deviations of particle velocities in the core region, the values for the three static bed heights unite to form two stages of evolutions with U_g, where the transition velocity between these stages is found associated to the appearing of a significant entrainment of solid particles. At this transition velocity, the transversal movement originally directed toward the center riser, undergo a change toward the wall beginning near the wall and spreading into a large part of the section riser with increasing U_g. A discussion on the boundary between the turbulent and fast fluidization regimes is made based on these results.     

Bactericidal effect of saffron (Crocus sativus L.) on Salmonella enterica during storage

The presence of pathogenic bacteria in spices represents a public health risk as a possible cause of food contamination. Salmonella has been found in several spices and it has been involved in food-borne outbreaks, but this bacterium has not been reported as a contaminant of saffron (Crocus sativus L.). We examined a possible antibacterial effect of saffron using samples from Iran, Greece and Spain which were artificially contaminated with clinical isolates belonging to five different serovars of Salmonella. We detected a loss of viability during the room-temperature storage of the saffron samples, with bacteria being undetectable at day 16 except in the case of the DT104 strain of the Typhimurium serovar, in all of the samples, and of the Hadar serovar in the Iranian sample, both of which gave negative culture at day 32. The laboratory strain LT2 of the Typhimurium serovar was undetectable at day 4. To gain an insight into the basis for this bactericidal effect, we measured the inhibitory and bactericidal concentrations of safranal and crocin, the main compounds responsible for the flavouring and colouring capabilities of saffron. They were in the order of 8–16 mg/mL and 64–128 mg/mL for safranal and crocin, respectively. These data suggest that these compounds, and probably their chemical relatives, are involved in the antibacterial activity of saffron, and that this effect can significantly reduce the risk of food contamination with Salmonella by this spice.     

Expression and effect of resistin on bovine and rat granulosa cell steroidogenesis and proliferation

Resistin, initially identified in adipose tissue and macrophages, was implicated in insulin resistance. Recently, its mRNA was found in hypothalamo-pituitary axis and rat testis, leading us to hypothesize that resistin may be expressed in ovary. In this study, we determined in rats and cows 1) the characterization of resistin in ovary by RT-PCR, immunoblotting, and immunohistochemistry and 2) the effects of recombinant resistin (10, 100, 333, and 667 ng/ml) ± IGF1 (76 ng/ml) on steroidogenesis, proliferation, and signaling pathways of granulosa cells (GC) measured by enzyme immunoassay, [(3)H]thymidine incorporation, and immunoblotting respectively. We observed that resistin mRNA and protein were present in several bovine and rat ovarian cells. Nevertheless, only bovine GC abundantly expressed resistin mRNA and protein. Resistin treatment decreased basal but not IGF1-induced progesterone (P<0.05; whatever the dose) and estradiol (P<0.005; for 10 and 333 ng/ml) production by bovine GC. In rats, resistin (10 ng/ml) increased basal and IGF1-induced progesterone secretion (P<0.0001), without effect on estradiol release. We found no effect of resistin on rat GC proliferation. Conversely, in cows, resistin increased basal proliferation (P<0.0001; for 100-667 ng/ml) and decreased IGF1-induced proliferation of GC (P<0.0001; for 10-333 ng/ml) associated with a decrease in cyclin D2 protein level (P<0.0001). Finally, resistin stimulated AKT and p38-MAPK phosphorylation in both species, ERK1/2-MAPK phosphorylation in rats and had the opposite effect on the AMPK pathway (P<0.05). In conclusion, our results show that resistin is expressed in rat and bovine ovaries. Furthermore, it can modulate GC functions in basal state or in response to IGF1 in vitro.     

Electrochemical analysis of proton and electron transfer equilibria of the reducible moieties in humic acids

Humic substances play a key role in biogeochemical and pollutant redox reactions. The objective of this work was to characterize the proton and electron transfer equilibria of the reducible moieties in different humic acids (HA). Cyclic voltammetry experiments demonstrated that diquat and ethylviologen mediated electron transfer between carbon working electrodes and HA. These compounds were used also to facilitate attainment of redox equilibria between redox electrodes and HA in potentiometric E(h) measurements. Bulk electrolysis of HA combined with pH-stat acid titration demonstrated that electron transfer to the reducible moieties in HA also resulted in proton uptake, suggesting decreasing reduction potentials E(h) of HA with increasing pH. This was confirmed by potentiometric E(h)-pH titrations of HA at different redox states. E(h) measurements of HA samples prereduced to different redox states by bulk electrolysis revealed reducible moieties in HA that cover a wide range of apparent standard reduction potentials at pH 7 from E(h)(0)* = +0.15 to -0.3 V. Modeling revealed an overall increase in the relative abundance of reducible moieties with decreasing E(h). The wide range of HA is consistent with its involvement in numerous environmental electron transfer reactions under various redox conditions.     

Quantifying the effect of heat stress on daily milk yield and monitoring dynamic changes using an adaptive dynamic model

Automation and use of robots are increasingly being used within dairy farming and result in large amounts of real time data. This information provides a base for the new management concept of precision livestock farming. From 2003 to 2006, time series of herd mean daily milk yield were collected on 6 experimental research farms in the Netherlands. These time series were analyzed with an adaptive dynamic model following a Bayesian method to quantify the effect of heat stress. The effect of heat stress was quantified in terms of critical temperature above which heat stress occurred, duration of heat stress periods, and resulting loss in milk yield. In addition, dynamic changes in level and trend were monitored, including the estimation of a weekly pattern. Monitoring comprised detection of potential outliers and other deteriorations. The adaptive dynamic model fitted the data well; the root mean squared error of the forecasts ranged from 0.55 to 0.99 kg of milk/d. The percentages of potential outliers and signals for deteriorations ranged from 5.5 to 9.7%. The Bayesian procedure for time series analysis and monitoring provided a useful tool for process control. Online estimates (based on past and present only) and retrospective estimates (determined afterward from all data) of level and trend in daily milk yield showed an almost yearly cycle that was in agreement with the calving pattern: most cows calved in winter and early spring versus summer and autumn. Estimated weekly patterns in terms of weekday effects could be related to specific management actions, such as change of pasture during grazing. For the effect of heat stress, the mean estimated critical temperature above which heat stress was expected was 17.8 ± 0.56°C. The estimated duration of the heat stress periods was 5.5 ± 1.03 d, and the estimated loss was 31.4 ± 12.2 kg of milk/cow per year. Farm-specific estimates are helpful to identify management factors like grazing, housing and feeding, that affect the impact of heat stress. The effect of heat stress can be decreased by modifying these factors.     

Iron deficiency enhances bioactive phenolics in lemon juice

BACKGROUND This study was designed to describe the phenolic status of lemon juice obtained from fruits of lemon trees differing in iron (Fe) nutritional status. Three types of Fe(III) compound were used in the experiment, namely a synthetic chelate and two complexes derived from natural polymers of humic and lignine nature. RESULTS All three Fe(III) compounds were able to improve the Fe nutritional status of lemon trees, though to different degrees. This Fe(III) compound effect led to changes in the polyphenol content of lemon juice. Total phenolics were decreased (～33% average decrease) and, in particular, flavanones, flavones and flavonols were affected similarly. CONCLUSION Iron‐deficient trees showed higher phenolic contents than Fe(III) compound‐treated trees, though Fe deficiency had negative effects on the yield and visual quality of fruits. However, from a human nutritional point of view and owing to the health‐beneficial properties of their bioavailable phenolic compounds, the nutritional quality of fruits of Fe‐deficient lemon trees in terms of phenolics was higher than that of fruits of Fe(III) compound‐treated lemon trees. Moreover, diosmetin‐6,8‐di‐C‐glucoside in lemon juice can be used as a marker for correction of Fe deficiency in lemon trees. Copyright © 2011 Society of Chemical Industry     

Factors influencing the production of volatile phenols by wine lactic acid bacteria

This work aimed to evaluate the effect of certain factors on the production of volatile phenols from the metabolism of p-coumaric acid by lactic acid bacteria (LAB) (Lactobacillus plantarum, L. collinoides and Pediococcus pentosaceus). The studied factors were: pH, L-malic acid concentration, glucose and fructose concentrations and aerobic/anaerobic conditions. It was found that, in the pH range of 3.5 to 4.5, the higher the pH the greater the production of volatile phenols. This behaviour is correlated with the effect of pH on bacterial growth. Increasing levels of L-malic acid in the medium diminished the production of 4-vinylphenol (4VP) and stimulated the production of 4-ethylphenol (4EP) by L. plantarum NCFB 1752 and L. collinoides ESB 99. The conversion of 4VP into 4EP by the activity of the vinylphenol reductase may be advantageous to the cells in the presence of L-malic acid, presumably due to the generation of NAD+, a cofactor required by the malolactic enzyme. Relatively high levels of glucose (20 g/L) led to an almost exclusive production of 4VP by L. plantarum NCFB 1752, while at low concentrations (≤ 5 g/L), 4EP is mainly or solely produced. Part of the glucose may be diverted to the production of mannitol as an alternative pathway to regenerate NAD+. This is corroborated by the experiments done with fructose, a compound that can be used as an electron acceptor by some bacteria becoming reduced to mannitol. In anaerobiosis, the reduction of 4VP into 4EP is clearly favoured, which is consistent with the need to increase the availability of NAD+ in these conditions. This study shows that the amount and the ratio 4VP/4EP produced by LAB are greatly affected by certain environmental and medium composition factors. The behaviour of the bacteria seems to be driven by the intracellular NAD+/NADH balance.     

Multiresidue determination of carcinogenic polycyclic aromatic hydrocarbons in honey by solid-phase extraction and high-performance liquid chromatography

An analytical procedure based on solid-phase extraction, using ethyl acetate as the elution solvent, and high-performance liquid chromatography with fluorescence and diode array detection was developed for the identification and quantification of polycyclic aromatic hydrocarbons (PAHs) in honey. The method has been optimized and validated in accordance with Commission Regulation 333/2007 and Commission Decision 2002/657/EC. This method allows the identification of the 15 PAHs that should be monitored in food matrices, as proposed in 2002 by the Scientific Committee on Food and later by the European Union in the Commission Recommendation 2005/108/EC, because of their genotoxic and carcinogenic properties. The results of the validation study were in agreement with quality criteria described in European legislation in terms of sensitivity, accuracy, and ruggedness, and the method was applied to the analysis of 42 honey samples (21 from Spain and 21 from other regions). The honey samples were not contaminated by PAHs at detectable levels and thus could be marketed without health risk.     

Phylogenetic distribution of fungal mycosporines within the Pucciniomycotina (Basidiomycota)

The synthesis of the UV Absorbing compounds named mycosporines (MYCs) has been detected in a few basidiomycetous yeast groups. Conspicuous accumulation of mycosporine-glutaminol-glucoside (MGG) in yeasts requires photo-induction and its photoprotective function has been postulated. The distribution of the ability to produce MYCs appeared to be related to the yeast taxonomic affiliation. In view of the potential significance of MYCs in yeast taxonomy, we here studied the distribution of this trait among dimorphic basidiomycetes of the Pucciniomycotina. Of the 94 fungal species (377 strains and 33 genera) tested, almost half were MYC-positive and MGG was the main compound produced. MGG synthesis was observed for representatives of five of seven Pucciniomycotina classes, indicating that this trait is widely distributed in this group. MGG detection proved useful for the differentiation of species of the polyphyletic genera, such as Rhodotorula and Sporobolomyces, that are phylogenetically separated. MGG quantification and UV tolerance studies in Cystobasidiomycetes supported the idea that the habitat of origin of each strains is important in the level of MGG synthesis and that MYCs have a photoprotective function in yeasts. The taxonomic value of this trait in fungal systematics is discussed.