Syngas biomethanation: In a transfer limited process, is CO inhibition an issue?

Syngas biomethanation is a promising technology in the process chain converting wastes to methane. However, gas-liquid mass transfer is a limiting factor of the biomethanation process. To reach high methane productivity, increasing the pressure is an interesting strategy to improve mass transfer. However, the CO content in the syngas raises concerns about a potential inhibition of the microorganisms. Therefore, the aim of the research was to assess the ability to work at high CO partial pressures. In this regard, a pressurized continuous stirred column with a working volume of 10L was implemented and a consortium adapted for syngas-biomethanation for 22 months was submitted to 100% CO and increasing pressure. No inhibition phenomenon was observed for logarithmic PCO as high as 1.8 bar (inlet pressure 5.0 bar), which was the first time that such a high CO partial pressure was tested in continuous mode. Mass transfer limitations allowed for the carboxydotrophic microorganisms to consume CO faster than it was transferred, allowing for the dissolved CO concentration to remain under inhibitory concentrations. These results question the habitual consensus that CO inhibition is a limiting factor of syngas biomethanation.

Syngas biomethanation: Study of process performances at high syngas flow rate in pressurized stirred column.

Syngas biomethanation is a promising technology for waste to energy conversion. However, it had not yet been tested at high syngas flow rates. The aim of this study was to assess the possibility for syngas biomethanation to reach high methane productivity at higher syngas inflow rate. A pressurized stirred column was implemented. The syngas inflow rate was gradually increased, and two different increase strategies were compared. The highest methane productivity achieved yet with syngas-biomethanation was obtained, with 23.2 LCH4/L/d, with high conversion efficiencies of 89% for H2 and 82% for CO. The mass transfer performances of the process were investigated, and the existence of a biological enhancement factor was observed. Considering an enhancement factor in bioprocesses is a pioneering concept that could change the way we design bioreactor to improve mass transfer. The high methane productivity obtained in this study paves the way for the process industrialization.

"Biomethanation of syngas by enriched mixed anaerobic consortium in pressurized agitated column".

In a circular economy approach, heterogeneous wastes can be upgraded to energy in the form of syngas via pyrogasification, and then to methane via biomethanation. Working at high pressure is a promising approach to intensify the process and to reduce gas-liquid transfer limitations. However, raising the pressure could lead to reaching the CO inhibition threshold of the microorganisms involved in syngas-biomethanation. To investigate the impact on pressure on the process, a 10L continuous stirred tank reactor working at 4 bars and 55 °C was implemented. Syngas (40% CO, 40% H2, 20% CO2) biomethanation was performed successfully and methane productivity as high as 6.8 mmolCH4/Lreactor/h with almost full conversion of CO (97%) and H2 (98%) was achieved. CO inhibition was investigated and carboxydotrophs appeared less resistant to high CO exposition than methanogens.

Dynamic observation of the biodegradation of lignocellulosic tissue under solid-state anaerobic conditions.

The solid-state anaerobic digestion (SS-AD) of wheat straw was characterized under low inoculated batch tests during 244 days. High levels of degradation of the cellulose (52%±1) and hemicelluloses (55%±2) were observed at the final stages and associated to a methane yield of 204±16 NmL gTS(-1). Ultrastructural observations, using transmission electronic microscopy, indicated that microorganisms degraded wheat straw from the central to the outer tissue (i.e. parenchyma to epidermis), depending on cell chemical, physical accessibility and the degree of lignification. Furthermore, major degradation of sclerenchyma secondary walls was observed. The bioaccessibility of lignocellulosic structures of wheat straw is mainly limited by the external waxy layer (cuticle), tertiary cell walls, high silica content and access to the cell lumen.

Substrate milling pretreatment as a key parameter for Solid-State Anaerobic Digestion optimization.

The effect of milling pretreatment on performances of Solid-State Anaerobic Digestion (SS-AD) of raw lignocellulosic residue is still controverted. Three batch reactors treating different straw particle sizes (milled 0.25 mm, 1 mm and 10 mm) were followed during 62 days (6 sampling dates). Although a fine milling improves substrate accessibility and conversion rate (up to 30% compared to coarse milling), it also increases the risk of media acidification because of rapid and high acids production during fermentation of the substrate soluble fraction. Meanwhile, a gradual adaptation of microbial communities, were observed according to both reaction progress and methanogenic performances. The study concluded that particle size reduction affected strongly the performances of the reaction due to an increase of substrate bioaccessibility. An optimization of SS-AD processes thanks to particle size reduction could therefore be applied at farm or industrial scale only if a specific management of the soluble compounds is established.

Storm-induced transfer of particulate trace metals to the deep-sea in the Gulf of Lion (NW Mediterranean Sea).

In order to calculate budgets of particulate matter and sediment-bound contaminants leaving the continental shelf of the Gulf of Lion (GoL), settling particles were collected in March 2011 during a major storm, using sediment traps. The collecting devices were deployed in the Cap de Creus submarine canyon, which represents the main export route. Particulate matter samples were analyzed to obtain mass fluxes and contents in organic carbon, Al, Cr, Co, Ni, Cu, Zn, Cd, Pb and La, Nd and Sm. The natural or anthropogenic origin of trace metals was assessed using enrichment factors (EFs). Results are that Zn, Cu and Pb appeared to be of anthropogenic origin, whereas Ni, Co and Cr appeared to be strictly natural. The anthropogenic contribution of all elements (except Cd) was refined by acid-leaching (HCl 1 N) techniques, confirming that Zn, Cu and Pb are the elements that are the most enriched. However, although those elements are highly labile (59-77%), they do not reflect severe enrichment (EFs <4). Most particles originate from the Rhone River. This has been confirmed by two different tracing procedures using rare earth elements ratios and concentrations of acid-leaching residual trace metals. Our results hence indicate that even in this western extremity of the GoL, storm events mainly export Rhone-derived particles via the Cap de Creus submarine canyons to the deep-sea environments. This export of material is significant as it represents about a third of the annual PTM input from the Rhone River.

Dynamic effect of total solid content, low substrate/inoculum ratio and particle size on solid-state anaerobic digestion.

Among all the process parameters of solid-state anaerobic digestion (SS-AD), total solid content (TS), inoculation (S/X ratio) and size of the organic solid particles can be optimized to improve methane yield and process stability. To evaluate the effects of each parameter and their interactions on methane production, a three level Box-Behnken experimental design was implemented in SS-AD batch tests degrading wheat straw by adjusting: TS content from 15% to 25%, S/X ratio (in volatile solids) between 28 and 47 and particle size with a mean diameter ranging from 0.1 to 1.4mm. A dynamic analysis of the methane production indicates that the S/X ratio has only an effect during the start-up phase of the SS-AD. During the growing phase, TS content becomes the main parameter governing the methane production and its strong interaction with the particle size suggests the important role of water compartmentation on SS-AD.

French Brittany macroalgae screening: composition and methane potential for potential alternative sources of energy and products.

Macroalgae are biomass resources that represent a valuable feedstock to be used entirely for human consumption or for food additives after some extractions (mainly colloids) and/or for energy production. In order to better develop the algal sector, it is important to determine the capacity of macroalgae to produce these added-values molecules for food and/or for energy industries on the basis of their biochemical characteristics. In this study, ten macroalgae obtained from French Brittany coasts (France) were selected. The global biochemical composition (proteins, lipids, carbohydrates, fibers), the presence and characteristics of added-values molecules (alginates, polyphenols) and the biochemical methane potential of these algae were determined. Regarding its biochemical composition, Palmaria palmata is interesting for food (rich in nutrients) and for anaerobic digestion (0.279 LCH4/gVS). Saccharina latissima could be used for alginate extraction (242 g/kgTS, ratio between mannuronic and guluronic acid M/G=1.4) and Sargassum muticum for polyphenol extraction (19.8 g/kgTS).

The French OQALI survey on dairy products: comparison of nutrient contents and other nutrition information on labels among types of brands.

BACKGROUND: Depending on their spending power, consumers may choose foodstuffs from more or less expensive types of brands (national, retailer, economy-line retailer or discount brands). The present study, on dairy products, assesses the nutritional composition and the frequencies of labelled nutrition parameters, according to types of brands. METHODS: The 1646 most consumed dairy products were collected. Nutrient contents and other labelled nutrition parameters provided on the packaging (i.e. nutrition and health claims, nutrition guidelines such as guideline daily amounts, consumption advice and information on added vitamins and minerals) were captured in the French branded product composition database (OQALI). RESULTS: Significant differences between brands were found for energy, protein, fat, saturates, carbohydrate, sugars, dietary fibre, calcium and sodium, in four of six dairy groups studied, but not systematically. National brands and retailer brands provided more detailed nutrition labelling and more frequent nutrition claims than cheaper brands. More retailer brand products provided nutrition guidelines and consumption advice than the other branded products. National brand products more frequently contained added vitamins and minerals and more frequently bore health claims. CONCLUSIONS: Nutrient contents of the cheaper brands of dairy products did not vary systematically from more expensive ones. However, national brands and retailer brands products provided more nutrition information on labels than the cheaper ones. There should be more detailed studies comparing different types of brands regarding labelling practices for nutrient contents and other nutrition information about foodstuffs to help prepare public health recommendations, adapted to all consumers, regardless of their income.

A restricted cubic spline approach to assess the association between high fat fish intake and red blood cell EPA + DHA content.

BACKGROUND AND AIMS: Fish, especially fatty fish, are the main contributor to eicosapentaenoic (EPA) and docosahexaenoic (DHA) intake. EPA and DHA concentrations in red blood cells (RBC) has been proposed as a cardiovascular risk factor, with <4% and >8% associated with the lowest and greatest protection, respectively. The relationship between high fat fish (HFF) intake and RBC EPA + DHA content has been little investigated on a wide range of fish intake, and may be non-linear. We aimed to study the shape of this relationship among high seafood consumers. METHODS AND RESULTS: Seafood consumption records and blood were collected from 384 French heavy seafood consumers and EPA and DHA were measured in RBC. A multivariate linear regression was performed using restricted cubic splines to consider potential non-linear associations. Thirty-six percent of subjects had an RBC EPA + DHA content lower than 4% and only 5% exceeded 8%. HFF consumption was significantly associated with RBC EPA + DHA content (P [overall association] = 0.021) adjusted for sex, tobacco status, study area, socioeconomic status, age, alcohol, other seafood, meat, and meat product intakes. This relationship was non-linear: for intakes higher than 200 g/wk, EPA + DHA content tended to stagnate. Tobacco status and fish contaminants were negatively associated with RBC EPA + DHA content. CONCLUSION: Because of the saturation for high intakes, and accounting for the concern with exposure to trace element contaminants, intake not exceeding 200 g should be considered.

Scriptaid and 5-aza-2'deoxycytidine enhanced expression of pluripotent genes and in vitro developmental competence in interspecies black-footed cat cloned embryos.

Somatic cell nuclear transfer offers the possibility of preserving endangered species including the black-footed cat, which is threatened with extinction. The effectiveness and efficiency of somatic cell nuclear transfer (SCNT) depends on a variety of factors, but 'inappropriate epigenetic reprogramming of the transplanted nucleus is the primary cause of the developmental failure of cloned embryos. Abnormal epigenetic events such as DNA methylation and histone modifications during SCNT perturb the expression of imprinted and pluripotent-related genes that, consequently, may result in foetal and neonatal abnormalities. We have demonstrated that pregnancies can be established after transfer of black-footed cat cloned embryos into domestic cat recipients, but none of the implanted embryos developed to term and the foetal failure has been associated to aberrant reprogramming in cloned embryos. There is growing evidence that modifying the epigenetic pattern of the chromatin template of both donor cells and reconstructed embryos with a combination of inhibitors of histone deacetylases and DNA methyltransferases results in enhanced gene reactivation and improved in vitro and in vivo developmental competence. Epigenetic modifications of the chromatin template of black-footed cat donor cells and reconstructed embryos with epigenetic-modifying compounds enhanced in vitro development, and regulated the expression of pluripotent genes, but these epigenetic modifications did not improve in vivo developmental competence.

Discontinuity induced angular distribution of photon plasmon coupling.

Metal-dielectric transitions are important structures that can display a host of optical characteristics including excitation of plasmons. Metal-dielectric discontinuities can furthermore support plasmon excitation without a severe condition on the incident angle of the exciting photons. Using a semi-infinite thin gold film, we study surface plasmon (SP) excitation and the associated electromagnetic near-field distribution by recording the resulting plasmon interference patterns. In particular, we measure interference periods involving SPs at the scanable metal/air interface and the buried metal/glass one. Supported by optical near-field simulations and experiments, we demonstrate that the metal/glass surface plasmon is observable over a wide range of incident angles encompassing values above and below the critical incident angle. As a result, it is shown that scanning near-field microscopy can provide quantitative evaluation of the real part of the buried surface plasmon wavevector.

Nutritional quality and labelling of ready-to-eat breakfast cereals: the contribution of the French observatory of food quality.

BACKGROUND/OBJECTIVES: To assess developments in the nutritional quality of food products in various food groups in France, an Observatory of Food Quality (Oqali) was created in 2008. To achieve its aims, Oqali built up a new database to describe each specific food item at the most detailed level, and also included economic parameters (market share and mean prices). The objective of this paper is to give a detailed analysis of the monitoring of the ready-to-eat breakfast cereals (RTEBCs) sector in order to show the benefits of the Oqali database. SUBJECTS/METHODS: Analysis was limited to products with nutritional information on labels. Packaging was provided by manufacturers or retailers, or obtained by buying products in regular stores. Economic parameters were obtained from surveys on French food consumption and data from consumer purchase panels. The breakfast cereal sector was divided into 10 categories and 5 types of brand. Oqali has developed anonymous indicators to describe product characteristics for each category of RTEBC and each type of brand by cross-referencing nutritional values with economic data. Packaging-related data were also analysed. The major nutritional parameters studied were energy, protein, fat, saturated fat, carbohydrates, sugars, fibre and sodium. Analysis was performed on the basis of descriptive statistics, multivariate statistics and a Kruskal-Wallis test. RESULTS: For the RTEBC, there is large variability in nutrient content throughout the sector, both within and between product categories. There is no systematic relation between brand type and nutritional quality within each product category, and the proportion of brand type within each product category is different. Nutritional labels, claims and pictograms are widespread on packages but vary according to the type of brand. CONCLUSIONS: These findings form the basis for monitoring developments in the nutritional composition and packaging-related data for breakfast cereals in the future. The final objective is to expand the approach illustrated here to all food sectors progressively.

Derivation of cat embryonic stem-like cells from in vitro-produced blastocysts on homologous and heterologous feeder cells.

The domestic cat is a focal mammalian species that is used as a model for developing assisted reproductive technologies for preserving endangered cats and for studying human diseases. The generation of stable characterized cat embryonic stem cells (ESC) lines to use as donor nuclei may help to improve the efficiency of interspecies somatic cell nuclear transfer for preserving endangered cats and allow the creation of knockout cell lines to generate knockout cats for studying function of specific genes related to human diseases. It will also enable the possibility of producing gametes in vitro from ESC of endangered cats. In the present study, we report the generation of cat embryonic stem-like (cESL) cells from blastocysts derived entirely in vitro. We generated 32 cESL cell lines from 331 in vitro derived blastocysts from which inner cell masses were isolated by immunosurgery or by a mechanical method. Inhibition of cat dermal fibroblast (CDF) proliferation after exposure to mitomycin-C was both dose and time dependent, where doses of 30 to 40 microg/mL for 5 h were most efficient. These dosages were higher than that required to inhibit cell proliferation of mouse fetal fibroblasts (MFF; 10 microg/mL for 2.5 h). Mitomycin-C did not significantly increase necrosis of cells from either species, and had an anti-proliferative effect at concentrations below cytotoxicity. A clear species-specific relationship between feeder layers and derivation of cESL cell lines was observed, where higher numbers of cESL cell lines were generated on homologous cat feeder layers (n = 26) than from those derived on heterologous mouse feeder layers (n = 6). Three cESL cell lines generated from immunosurgery and cultured on CDF maintained self-renewal and were morphologically undifferentiated for nine and twelve passages (69-102 days). These lines showed a tightly packed dome shaped morphology, exhibited alkaline phosphatase activity and immuno-expression of the pluripotent marker OCT-4 and surface marker SSEA-1. Primary colonies at P0 to P3 and cat blastocysts expressed transcription factors OCT-4, NANOG and SOX-2 and the proto-oncogene C-MYC. However, expression was at levels significantly lower than in vitro produced blastocysts. During culture, cESL colonies spontaneously differentiated into fibroblasts, cardiomyocytes, and embryoid bodies. Development of techniques to prevent differentiation of cESL cells will be essential for maintaining defined cell lines.

Pretreatment methods to improve sludge anaerobic degradability: a review.

This paper presents a review of the main sludge treatment techniques used as a pretreatment to anaerobic digestion. These processes include biological (largely thermal phased anaerobic), thermal hydrolysis, mechanical (such as ultrasound, high pressure and lysis), chemical with oxidation (mainly ozonation), and alkali treatments. The first three are the most widespread. Emphasis is put on their impact on the resulting sludge properties, on the potential biogas (renewable energy) production and on their application at industrial scale. Thermal biological provides a moderate performance increase over mesophilic digestion, with moderate energetic input. Mechanical treatment methods are comparable, and provide moderate performance improvements with moderate electrical input. Thermal hydrolysis provides substantial performance increases, with a substantial consumption of thermal energy. It is likely that low impact pretreatment methods such as mechanical and thermal phased improve speed of degradation, while high impact methods such as thermal hydrolysis or oxidation improve both speed and extent of degradation. While increased nutrient release can be a substantial cost in enhanced sludge destruction, it also offers opportunities to recover nutrients from a concentrated water stream as mineral fertiliser.

Combined thermophilic aerobic process and conventional anaerobic digestion: effect on sludge biodegradation and methane production.

The efficiency of hyper-thermophilic (65 degrees Celsius) aerobic process coupled with a mesophilic (35 degrees Celsius) digester was evaluated for the activated sludge degradation and was compared to a conventional mesophilic digester. For two Sludge Retention Time (SRT), 21 and 42 days, the Chemical Oxygen Demand (COD) solubilisation and biodegradation processes, the methanisation yield and the aerobic oxidation were investigated during 180 days. The best results were obtained at SRT of 44 days; the COD removal yield was 30% higher with the Mesophilic Anaerobic Digestion/Thermophilic Aerobic Reactor (MAD-TAR) co-treatment. An increase of the sludge intrinsic biodegradability is also observed (20-40%), showing that the unbiodegradable COD in mesophilic conditions becomes bioavailable. However, the methanisation yield was quite similar for both processes at a same SRT. Finally, such a process enables to divide by two the volume of digester with an equivalent efficiency.

[Allergic asthma due to sausage mould]. / Asthme allergique à la "fleur de saucisson"

INTRODUCTION: Chronic cough is a common reason for consultation in respiratory medicine. The three most frequent causes of chronic cough are asthma, postnasal drip syndrome or rhinosinusitis, and gastro-oesophageal reflux disease. CASE REPORT: We describe a case of chronic cough related to occupational asthma with sensitivity to dry sausage mould (Penicillium nalgiovensis) in a worker in a semi-industrial pork butchers. The diagnosis was based on the history of symptoms, positive skin prick-tests, spirometry, a normal pulmonary CT-scan, and a favourable outcome after avoidance of the allergen. It was notified as a case of occupational disease. CONCLUSION: A diagnosis of asthma should be considered in a worker exposed to dry sausage mould presenting with respiratory symptoms like chronic cough without evidence of hypersensitivity pneumonitis. Skin prick-tests and allergen avoidance are useful in the diagnosis.

Birth of domestic cat kittens of predetermined sex after transfer of embryos produced by in vitro fertilization of oocytes with flow-sorted sperm.

Our goals were to: (1) determine if domestic cat sperm could be sorted to high purity by flow cytometry after overnight shipment of cooled samples; (2) evaluate the efficiency with which sorted sperm could be used to generate cat embryos in vitro; and (3) determine if live kittens of predetermined sex could be produced after transfer of embryos derived by IVF using sorted sperm. Semen samples (n=5) from one male were extended in electrolyte-free solution and shipped overnight at 4 degrees C to the sorting facility. Samples were adjusted to 75x10(6)sperm/mL and stained with Hoechst 33342. After 1h at 34.5 degrees C, samples were adjusted to 50x10(6)sperm/mL with 4% egg yolk TALP+0.002% food dye and sorted by high-speed flow cytometry. Later resort analysis confirmed purities of 94% and 83% for X- and Y-chromosome bearing sperm, respectively. Sorted sperm were centrifuged, re-suspended in TEST yolk buffer and shipped overnight to the IVF laboratory. After IVF of in vivo matured oocytes with X-chromosome bearing sperm, cleavage frequency was 62% (54/87). After IVF of IVM oocytes with control, X- or Y-chromosome bearing sperm, the incidence of cleavage was 42% (48/115), 33% (40/120), and 35% (52/150), respectively, and blastocyst development was 53% (21/40), 50% (11/22), and 55% (23/42), respectively (P>0.05). On Day 2, 45 embryos produced by IVF of in vivo matured oocytes with X-chromosome bearing sperm were transferred to the oviduct of four Day 1 recipients, three of which subsequently delivered litters of one, four, and seven female kittens, respectively. In conclusion, we confirmed that sperm sorting technology can be applied to domestic cats and established that kittens of predetermined sex can be produced.

Io volcanism seen by new horizons: a major eruption of the Tvashtar volcano.

Jupiter's moon Io is known to host active volcanoes. In February and March 2007, the New Horizons spacecraft obtained a global snapshot of Io's volcanism. A 350-kilometer-high volcanic plume was seen to emanate from the Tvashtar volcano (62 degrees N, 122 degrees W), and its motion was observed. The plume's morphology and dynamics support nonballistic models of large Io plumes and also suggest that most visible plume particles condensed within the plume rather than being ejected from the source. In images taken in Jupiter eclipse, nonthermal visible-wavelength emission was seen from individual volcanoes near Io's sub-Jupiter and anti-Jupiter points. Near-infrared emission from the brightest volcanoes indicates minimum magma temperatures in the 1150- to 1335-kelvin range, consistent with basaltic composition.

[Medical treatment in peripheral arterial disease: a professional practice study in 262 patients]. / Traitement médical de l'artériopathie oblitérante des membres inférieurs: étude de pratique professionnelle chez 262 patients.

PURPOSE: Antiplatelet agents (APA), statins and angiotensin converting enzyme inhibitors (ACEI) are effective to reduce the risk of cardio-vascular events in patients with peripheral arterial disease (PAD). Few data are available on the actual prescription of these drugs in outpatients and on the effect of hospital care on the level of prescription. METHODS: Retrospective study of patients hospitalized with a confirmed diagnosis of PAD over a one-year period. Comparison of medical treatments on admission and on discharge. RESULTS: 262 patients were included. Mean age was 73 +/- 11 years, and 29% of the patients were women. APA were present in 64% on admission and in 83% when discharged (P < 0.0001). A statin was present in 29% on admission and in 38% when discharged (P = 0.001). ACEI were present in 27% on admission and in 32% when discharged (P= 0.02). A vasodilator was present in 47% on admission and 52% when discharged (P = 0.1). 35% of the patients had isolated PAD. Compared to the patients with associated clinical coronary or cerebro-vascular disease, they were less frequently discharged on statins (respectively 26 and 45%, p = 0.003) and on ACEI (respectively 23 et 38%, P = 0.016) whereas APA were equally prescribed (respectively 82 and 84%, P= 0.7). CONCLUSION: APA were prescribed to a majority of outpatients and the level of prescription was further improved when patients were discharged from the hospital. Statins and ACEI were insufficiently prescribed. On the other hand, vasodilator therapy remained still largely prescribed, despite the lack of any strong effect on morbidity and survival.