Catalytic gasification of biomass (Miscanthus) enhanced by CO2 sorption

The main objective of this work concerns the coupling of biomass gasification reaction and CO₂ sorption. The study shows the feasibility to promote biomass steam gasification in a dense fluidized bed reactor with CO₂ sorption to enhance tar removal and hydrogen production. It also proves the efficiency of CaO-Ca₁₂Al₁₄O₃₃/olivine bi-functional materials to reduce heavy tar production. Experiments have been carried out in a fluidized bed gasifier using steam as the fluidizing medium to improve hydrogen production. Bed materials consisting of CaO-based oxide for CO₂ sorption (CaO-Ca₁₂Al₁₄O₃₃) deposited on olivine for tar reduction were synthesized, their structural and textural properties were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and temperature-programmed reduction (TPR) methods, and the determination of their sorption capacity and stability analyzed by thermogravimetric analysis (TGA). It appears that this CaO-Ca₁₂Al₁₄O₃₃/olivine sorbent/catalyst presents a good CO₂ sorption stability (for seven cycles of carbonation/decarbonation). Compared to olivine and Fe/olivine in a fixed bed reactor for steam reforming of toluene chosen as tar model compound, it shows a better hydrogen production rate and a lower CO₂ selectivity due to its sorption on the CaO phase. In the biomass steam gasification, the use of CaO-Ca₁₂Al₁₄O₃₃/olivine as bed material at 700 °C leads to a higher H₂ production than olivine at 800 °C thanks to CO₂ sorption. Similar tar concentration and lighter tar production (analyzed by HPLC/UV) are observed. At 700 °C, sorbent addition allows to halve tar content and to eliminate the heaviest tars.

Measurement of the 1H(γ, p)π0 reaction using a novel nucleon spin polarimeter

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(γ, p)π0 in the range 0.4<Eγ<1.4  GeV validates the technique and provides essential new data to constrain the excitation spectrum of the nucleon.

Extended Spectrum Beta-Lactamase-ProducingKlebsiella pneumoniaeOutbreaks During a Third Generation Cephalosporin Restriction Policy

In spite of the adoption of third generation cephalosporin restriction policies, two independent outbreaks by Extended Spectrum Beta-Lactamase (ESBL)-producing Klebsiella pneumoniae occurred in two different wards (Neonatal Intensive Care Unit, NICU and Neurosurgery) of a teaching hospital in Rome, Italy. In the former 19 infected neonates were reported, whereas in the latter there were 10 infected patients. In both wards no differences were observed in the mortality rates in periods of outbreak and those with no outbreak. Molecular typing on a total of 19 isolated strains was carried out and restriction patterns were compared. The PFGE showed that nine isolates responsible for infection in the NICU were all included in three closely related clusters. In Neurosurgery nine strains out of ten were strictly related and part of an outbreak occurring between August-December 2003, while one isolate was temporarily (February 2003) and genetically (seven band differences) unrelated to the outbreak strains. When ESBL producing K. pneumoniae clusters from the two wards (NICU vs Neurosurgery) were compared, they appeared to be completely different both for their genotype pattern and plasmid type or presence, thus demonstrating cross transmission by two different genotypes.

Gut-associated bacterial microbiota in paediatric patients with inflammatory bowel disease

BACKGROUND

Clinical and experimental observations in animal models indicate that intestinal commensal bacteria are involved in the initiation and amplification of inflammatory bowel disease (IBD). No paediatric reports are available on intestinal endogenous microflora in IBD.

AIMS

To investigate and characterise the predominant composition of the mucosa-associated intestinal microflora in colonoscopic biopsy specimens of paediatric patients with newly diagnosed IBD.

METHODS

Mucosa-associated bacteria were quantified and isolated from biopsy specimens of the ileum, caecum and rectum obtained at colonoscopy in 12 patients with Crohn's disease, 7 with ulcerative colitis, 6 with indeterminate colitis, 10 with lymphonodular hyperplasia of the distal ileum and in 7 controls. Isolation and characterisation were carried out by conventional culture techniques for aerobic and facultative-anaerobic microorganisms, and molecular analysis (16S rRNA-based amplification and real-time polymerase chain reaction assays) for the detection of anaerobic bacterial groups or species.

RESULTS

A higher number of mucosa-associated aerobic and facultative-anaerobic bacteria were found in biopsy specimens of children with IBD than in controls. An overall decrease in some bacterial species or groups belonging to the normal anaerobic intestinal flora was suggested by molecular approaches; in particular, occurrence of Bacteroides vulgatus was low in Crohn's disease, ulcerative colitis and indeterminate colitis specimens.

CONCLUSION

This is the first paediatric report investigating the intestinal mucosa-associated microflora in patients of the IBD spectrum. These results, although limited by the sample size, allow a better understanding of changes in mucosa-associated bacterial flora in these patients, showing either a predominance of some potentially harmful bacterial groups or a decrease in beneficial bacterial species. These data underline the central role of mucosa-adherent bacteria in IBD.