10 research outputs found

    N2O decomposition and reduction on Co-MOR, Fe-MOR and Ni-MOR catalysts: in situ UV–vis DRS and operando FTIR investigation. An insight on the reaction pathways

    No full text
    Co-, Fe- or Ni-exchanged Na-MOR (Si/Al = 9.2) were prepared by ion-exchange method. The catalytic activity for N2O decomposition in the absence or in the presence of NO and for N2O reduction with CH4 in the absence of O2 (CRN2O), or in the presence of O2 (SCRN2O) was investigated. The catalytic measurements were performed in a flow apparatus with GC analysis of reactants and products. On Fe-MOR, in situ FTIR and UV–vis characterization evidenced coordinatively unsaturated sites (c.u.s.) Fe2+ arising from two families of Fe3+ dimers with different reducibility. Characterization and catalytic results combined with operando FTIR experiments gave an insight into the transition metal ion (tmi) species working during N2O abatement and into the reaction pathways. For N2O decomposition the activity order was Co-MOR > Fe-MOR in the absence of NO and Fe-MOR ≥ Co-MOR in the presence of NO, whereas Ni-MOR was always inactive. The decomposition occurred via redox mechanism passing through the formation of activated surface oxygen species, Oads *. The quasi-oxidic character of this activated oxygen in the Fe3+-O(1+δ)−—Fe(2+δ)+ intermediates with respect to the oxyl character of that in Co3+O‒ intermediates accounted for the lower activity and for the activity enhancement by NO addition to the feed of Fe-MOR with respect to Co-MOR. In Ni-MOR, both isolated or dimeric Ni2+ species were unable to be oxidized by N2O yielding Oads *. For N2O reduction, (CRN2O) and (SCRN2O), the activity order was Fe-MOR > Ni-MOR > Co-MOR. On all catalysts operando FTIR experiments revealed CHxOy intermediates (methoxy, formaldehyde and two types of formate species). The investigation of surface species changing the addition order of the reactants evidenced that the formation of CHxOy intermediates was favored on Co-MOR by pre-saturation with N2O, that yielded Co3+O− able to activate CH4, whereas on Ni-MOR by pre-saturation with CH4, that reduced Ni2+ dimers to Ni+ dimers, able to activate N2O. On Fe-MOR, the Fe2+ dimers formed during activation behaved as Co2+, whereas the Fe2+ dimers formed by reduction with CH4 behaved as Ni+ dimers. The formation and the stability of Oads * surface species were key factors for N2O decomposition and reduction pathways. These factors were affected by the mobility of the tmi electrons, that depends on the oxidation state, nuclearity and location in MOR framework of tmi. © 2018 Elsevier B.V

    N2O decomposition on CoOx, CuOx, FeOx or MnOx supported on ZrO2: The effect of zirconia doping with sulfates or K+ on catalytic activity

    No full text
    Zirconia doped with sulfates or K+ were prepared by impregnation with (NH4)2SO4, or KNO3 aqueous solutions. MeOx/ZrO2 and MeOx/doped-ZrO2 catalysts (Me=Co, Cu, Fe or Mn) were prepared by wet impregnation of zirconia and doped-zirconia supports. The effect of doping on MeOx properties was studied by XRD, UV-vis DRS, H2-TPR and FTIR and the influence of doping on the catalytic activity for N2O decomposition was investigated under ideal conditions (N2O in He) and under real reaction conditions (addition of NO, O2, and water vapour to the reactant mixture).Characterization results indicated that all samples contained mainly dispersed Men+ species interacting with the support. In MeOx/sulfated-ZrO2 the doping with electron-withdrawing sulfates stabilized the Men+ oxidation state. In CoOx/K-ZrO2 samples the doping with electron-releasing K+ increased the poly-nuclear CoOx reducibility. FTIR characterization suggested that the electron-donor capacity of Co2+ site had the order CoOx/sulfated-ZrO

    CoOx and FeOx supported on ZrO2 for the simultaneous abatement of NOx and N2O with C3H6 in the presence of O2

    No full text
    MeOx/ZrO2 (Me = Co and Fe) catalysts were studied for the simultaneous selective catalytic reduction of NO and N2O in the presence of O2 using C3H6 as reducing agent (SCRsim). To give a better insight in the simultaneous process we investigated the reactions related to SCRsim (SCRN2O, SCRNO, N2O decomposition and C3H6 combustion) as well as the abatements in the absence of O2 (CRsim, CRN2O, CRNO). Catalytic results showed that, in the presence of O2 excess, CoOx/ZrO2 and FeOx/ZrO2 catalysts were scarcely active and unselective for the separate NO and N2O abatements with C3H6 and are ineffective for their simultaneous abatement. Because C3H6 preferentially reacted with O2, NO was poorly reduced and N2O was abated, at a temperature above that of complete C3H6 conversion, via both SCRN2O and decomposition. Conversely, in the absence of O2 in the feed, on both catalysts NO and N2O were efficiently reduced by C3H6, but undesired by-products formed. The activity for SCRsim strongly depended on the C3H6/O2 feeding ratio. With suitable feeding mixture O2 was completely consumed and the residual propene efficiently and simultaneously reduced NO and N2O, with negligible formation of by-products. In hydrothermal conditions both catalysts were slightly and reversibly deactivated. Characterization by XRD, UV–vis DRS and FTIR after catalytic experiments showed that dispersed Co2+ and Fe3+ species were stable on zirconia surface and that no significant segregation phenomena occurred in hydrothermal conditions

    Cephalometric effects of the elastodontic appliance in managing skeletal Class II division 1 cases

    Get PDF
    Abstract Aim The aim of the study was to evaluate the cephalometric effects of the elastodontic appliance (EA) in the management of patients presenting with a skeletal Class II/1 malocclusion. Methods Twenty Class II patients treated using the EA (Group EA) were compared with 20 Class II untreated children (Group C). Cephalograms were compared at the start (T0) and after 24 months (T1) after which time, skeletal, dental, and aesthetic variables were evaluated. A statistical evaluation was conducted by applying an unpaired t-test for normally distributed variables. Results From T0 to T1, the EA group showed a significant increase in lower facial height (LFH), in mandibular length (Co-Gn), in the upper incisor and cranial plane angle (1 + SN) and in the distance between a true vertical line (TVL)-soft tissue B (B') and TVL-soft tissue Pogonion (Pog') points. From T0 to T1, group C showed a significant decrease in SN-occlusal plane (PO) (p < 0.01), of SN-mandibular plane (Go-Me) (p < 0.01) and of total gonial (N-Go-Me) angles (p < 0.05); a significant reduction of the distance between TVL-upper incisor (1+), TVL-lower lip (Li), and TVL-Pog' was shown. No statistical differences were observed between the groups in dental and aesthetic outcomes, except for a skeletal increase in LFH (p < 0.05) and in Co-Gn length (p < 0.05), which was statistically significant in the EA group. Conclusion In Class II growing patients, the EA induces minor skeletal effects, compared to untreated control patients

    The burden of bacteremia and invasive diseases in children aged less than five years with fever in Italy

    No full text
    Background: Invasive diseases (ID) caused by Streptococcus pneumoniae (S. pneumoniae), Haemophilus influenzae (H. influenzae), and Neisseria meningitidis are a major public health problem worldwide. Comprehensive data on the burden of bacteremia and ID in Italy, including data based on molecular techniques, are needed. Methods: We conducted a prospective, multi-centre, hospital-based study (GSK study identifier: 111334) to assess the burden of bacteremia and ID among children less than five years old with a fever of 39 °C or greater. Study participation involved a single medical examination, collection of blood for polymerase chain reaction (PCR) and blood culture, and collection of an oropharyngeal swab for colonization analysis by PCR. Results: Between May 2008 and June 2009, 4536 patients were screened, 944 were selected and 920 were enrolled in the study. There were 225 clinical diagnoses of ID, 9.8 % (22) of which were bacteremic. A diagnosis of sepsis was made for 38 cases, 5.3 % (2) of which were bacteremic. Among the 629 non-ID diagnoses, 1.6 % (10) were bacteremic. Among the 34 bacteremic cases, the most common diagnoses were community-acquired pneumonia (15/34), pleural effusion (4/34) and meningitis (4/34). S. pneumoniae was the most frequently detected bacteria among bacteremic cases (29/34) followed by H. influenzae (3/34). Ninety percent (27/30) of bacteremic patients with oropharyngeal swab results were colonized with the studied bacterial pathogens compared to 46.1 % (402/872) of non-bacteremic cases (p < 0.001). PCV7 (7-valent pneumococcal conjugate vaccine) vaccination was reported for 55.9 % (19/34) of bacteremic cases. S. pneumoniae serotypes were non-vaccine serotypes in children who had been vaccinated. Mean duration of hospitalization was longer for bacteremic cases versus non-bacteremic cases (13.6 versus 5.8 days). Conclusions: These results confirm that S. pneumoniae is one of the pathogens frequently responsible for invasive disease

    IL-23 secreted by myeloid cells drives castration-resistant prostate cancer

    Get PDF
    Patients with prostate cancer frequently show resistance to androgen-deprivation therapy, a condition known as castration-resistant prostate cancer (CRPC). Acquiring a better understanding of the mechanisms that control the development of CRPC remains an unmet clinical need. The well-established dependency of cancer cells on the tumour microenvironment indicates that the microenvironment might control the emergence of CRPC. Here we identify IL -23 produced by myeloid-derived suppressor cells (MDSCs) as a driver of CRPC in mice and patients with CRPC. Mechanistically, IL-23 secreted by MDSCs can activate the androgen receptor pathway in prostate tumour cells, promoting cell survival and proliferation in androgen-deprived conditions. Intra-tumour MDSC infiltration and IL-23 concentration are increased in blood and tumour samples from patients with CRPC. Antibody-mediated inactivation of IL-23 restored sensitivity to androgen-deprivation therapy in mice. Taken together, these results reveal that MDSCs promote CRPC by acting in a non-cell autonomous manner. Treatments that block IL-23 can oppose MDSC-mediated resistance to castration in prostate cancer and synergize with standard therapies

    Breakthrough Cancer Pain: Preliminary Data of The Italian Oncologic Pain Multisetting Multicentric Survey (IOPS-MS)

    No full text
    Introduction: An ongoing national multicenter survey [Italian Oncologic Pain multiSetting Multicentric Survey (IOPS-MS)] is evaluating the characteristics of breakthrough cancer pain (BTP) in different clinical settings. Preliminary data from the first 1500 cancer patients with BTP enrolled in this study are presented here. Methods: Thirty-two clinical centers are involved in the survey. A diagnosis of BTP was performed by a standard algorithm. Epidemiological data, Karnofsky index, stage of disease, presence and sites of metastases, ongoing oncologic treatment, and characteristics of background pain and BTP and their treatments were recorded. Background pain and BTP intensity were measured. Patients were also questioned about BTP predictability, BTP onset (≤10 or >10 min), BTP duration, background and BTP medications and their doses, time to meaningful pain relief after BTP medication, and satisfaction with BTP medication. The occurrence of adverse reactions was also assessed, as well as mucosal toxicity. Results: Background pain was well controlled with opioid treatment (numerical rating scale 3.0 ± 1.1). Patients reported 2.5 ± 1.6 BTP episodes/day with a mean intensity of 7.5 ± 1.4 and duration of 43 ± 40 min; 977 patients (65.1%) reported non-predictable BTP, and 1076 patients (71.7%) reported a rapid onset of BTP (≤10 min). Higher patient satisfaction was reported by patients treated with fast onset opioids. Conclusions: These preliminary data underline that the standard algorithm used is a valid tool for a proper diagnosis of BTP in cancer patients. Moreover, rapid relief of pain is crucial for patients’ satisfaction. The final IOPS-MS data are necessary to understand relationships between BTP characteristics and other clinical variables in oncologic patients. Funding: Molteni Farmaceutici, Italy
    corecore