31 research outputs found

    Investigating the Impact of Non-Hydrodynamically Connected Descaling Parameters in the Removal of Different Stages of Paraffin Deposits Using Multiple Nozzles in Petroleum Production Tubing

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    Despite the continued research efforts in understanding the erosional behaviors of multiple flat fan nozzles in the removal of different types of scale deposits from petroleum production tubing. The non-hydrodynamically connected descaling parameters such as stand-off distance, nozzle arrangement and chamber pressure have not been duly considered up to date. This research utilizes 3-flat fan high-pressure nozzles at a high injection pressure of 10 MPa to remove paraffin deposits at different growth stages from petroleum production tubing to evaluate the effects of the descaling parameters on scale removal. A stand-off distance of 25 mm, 50 mm and 75 mm; nozzle arrangement in novel orientations (triangle, diagonal & right-angle) involving 7-nozzles header and chamber pressures (in compression – 0.2 MPa and vacuum -8.0 x10-3 MPa) were utilized as the varying non-hydrodynamically connected parameters. Generally, the selection of both nozzle arrangement and chamber air concentration was found to be governed by the type and shape of the deposit in question while the scale removal capability was found to be reduced with an increase in stand-off distance due to poor jet contact. An average hollow shaped paraffin removal of 276 g, 259 g and 226 g were recorded at ambient condition across the respective stand-off distance of the three respective nozzles arrangements. While the introduction of 0.2 MPa compressed air significantly increased the respective removal of the early stage paraffin deposition to 342 g, 299 g and 277 g respectively. Also, more hollow shaped removal improvement of 366 g, 320 g and 288 g were achieved after suctioning the chamber by -0.008 MPa, while simultaneously pumping water at 10 MPa. The case of solid shaped paraffin signifying complete tubing blockage was not effective at ambient condition, with average paraffin removal of 99 g, 126 g and 112 g respectively. However, the introduction of compressed chamber air registered the best solid paraffin removal results of 235 g, 286 g and 256 g respectively. Whereas the suction operation recorded an average removal of 229 g, 270 g and 250 g of paraffin across the respective jet positions and nozzle configurations. This result provides a practical approach to the removal of organic scales deposits at varying descaling conditions of injection pressure, standoff distance and nozzle arrangement

    Immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) formulated with 2-phenoxyethanol in multidose vials given with routine vaccination in healthy infants: An open-label randomized controlled trial.

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    BACKGROUND: This open-label randomized controlled trial in infants compared safety, tolerability, and immunogenicity of the 13-valent pneumococcal conjugate vaccine (PCV13) formulated with the preservative 2-phenoxyethanol (2-PE) in a multidose vial (MDV) to the current PCV13 without 2-PE in a single-dose syringe (SDS). METHODS: Gambian infants were randomized 1:1 to receive PCV13 as either MDV or SDS at ages 2, 3, and 4months. Serotype-specific antipneumococcal antibody responses and opsonophagocytic activity ([OPA]; subset) were measured at age 5months. Noninferiority was declared if the lower bound of the 97.5% CI for the difference (MDV-SDS) in proportions of subjects achieving IgG concentrations ≥0.35μg/mL (primary endpoint) was greater than -10%. IgG geometric mean concentrations (GMCs) were noninferior if the lower limit of the two-sided 97.5% CI of the geometric mean ratio (MDV vs SDS) was greater than 0.5. Reactogenicity and other adverse events were collected. RESULTS: 500 participants were randomized and vaccinated; 489 (MDV: n=245; SDS: n=244) completed the trial. Noninferiority of MDV was demonstrated for all serotypes as measured by percentage of subjects achieving antibody responses above ≥0.35μg/mL. IgG GMCs (coprimary endpoint) also demonstrated noninferiority of MDV; OPA results supported these findings. Safety and tolerability were comparable between groups. CONCLUSIONS: PCV13 in MDV was safe and immunogenic when administered according to the routine schedule to infants. MDV was noninferior to SDS for all 13 pneumococcal serotypes. Comparable immunogenicity and safety profiles of PCV13 MDV and SDS suggest PCV13 MDV can help optimize vaccination in resource-limited settings. ClinicalTrials.gov NCT01964716 https://clinicaltrials.gov/ct2/show/NCT01964716

    Hepatitis B Co-Infection is Associated with Poorer Survival of HIV-Infected Patients on Highly Active Antiretroviral Therapy in West Africa

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    Background: Hepatitis B has been reported to be high in HIV-infected African populations. However, the impact of this co-infection on the survival of HIV-infected Africans on long-term highly active antiretroviral therapy (HAART) remains poorly characterised. We investigated the impact of HBV/HIV co-infection on survival of HIV infected patients undergoing antiretroviral therapy in a West African population. Methods: This was a clinic-based cohort study of HIV-infected adults enrolled in Nigeria, West Africa. Study subjects (9,758) were screened for hepatitis B and hepatitis C at HAART initiation. Kaplan-Meier survival and Cox proportional hazards models were used to estimate probability of survival and to identify predictors of mortality respectively, based on hepatitis B surface antigen status. All patients had signed an informed written consent before enrolment into the study; and we additionally obtained permission for secondary use of data from the Harvard institutional review board. Results: Patients were followed up for a median of 41 months (interquartile range: 30–62 months) during which, 181 (1.9%) patients died. Most of the deaths; 143 (79.0%) occurred prior to availability of Tenofovir. Among those that were on antiretroviral therapy, hepatitis B co-infected patients experienced a significantly lower survival than HIV mono-infected patients at 74 months of follow up (94% vs. 97%; p=0.0097). Generally, hepatitis B co-infection: HBsAg-positive/HIV-positive (Hazards Rate [HR]; 1.5: 95% CI 1.09–2.11), co-morbid tuberculosis (HR; 2.2: 95% CI 1.57–2.96) and male gender (HR; 1.5: 95% CI 1.08–2.00) were significantly predictive of mortality. Categorising the patients based on use of Tenofovir, HBV infection failed to become a predictor of mortality among those on Tenofovir-containing HAART. Conclusions: HBsAg-positive status was associated with reduced survival and was an independent predictor of mortality in this African HIV cohort on HAART. However, Tenofovir annulled the impact of HBV on mortality of HIV patients in the present study cohort

    Patient Retention and Adherence to Antiretrovirals in a Large Antiretroviral Therapy Program in Nigeria: A Longitudinal Analysis for Risk Factors

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    Substantial resources and patient commitment are required to successfully scale-up antiretroviral therapy (ART) and provide appropriate HIV management in resource-limited settings. We used pharmacy refill records to evaluate risk factors for loss to follow-up (LTFU) and non-adherence to ART in a large treatment cohort in Nigeria.We reviewed clinic records of adult patients initiating ART between March 2005 and July 2006 at five health facilities. Patients were classified as LTFU if they did not return >60 days from their expected visit. Pharmacy refill rates were calculated and used to assess non-adherence. We identified risk factors associated with LTFU and non-adherence using Cox and Generalized Estimating Equation (GEE) regressions, respectively. Of 5,760 patients initiating ART, 26% were LTFU. Female gender (p < 0.001), post-secondary education (p = 0.03), and initiating treatment with zidovudine-containing (p = 0.004) or tenofovir-containing (p = 0.05) regimens were associated with decreased risk of LTFU, while patients with only primary education (p = 0.02) and those with baseline CD4 counts (cell/ml(3)) >350 and <100 were at a higher risk of LTFU compared to patients with baseline CD4 counts of 100-200. The adjusted GEE analysis showed that patients aged <35 years (p = 0.005), who traveled for >2 hours to the clinic (p = 0.03), had total ART duration of >6 months (p<0.001), and CD4 counts >200 at ART initiation were at a higher risk of non-adherence. Patients who disclosed their HIV status to spouse/family (p = 0.01) and were treated with tenofovir-containing regimens (p < or = 0.001) were more likely to be adherent.These findings formed the basis for implementing multiple pre-treatment visit preparation that promote disclosure and active community outreaching to support retention and adherence. Expansion of treatment access points of care to communities to diminish travel time may have a positive impact on adherence
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