Time-Dependent Propensity Score for Assessing the Effect of Vaccine Exposure on Pregnancy Outcomes through Pregnancy Exposure Cohort Studies

Women are advised to be vaccinated for influenza during pregnancy and may receive vaccine at any time during their pregnancy. In observational studies evaluating vaccine safety in pregnancy, to account for such time-varying vaccine exposure, a time-dependent predictor can be used in a proportional hazards model setting for outcomes such as spontaneous abortion or preterm delivery. Also, due to the observational nature of pregnancy exposure cohort studies and relatively low event rates, propensity score (PS) methods are often used to adjust for potential confounders. Using Monte Carlo simulation experiments, we compare two different ways to model the PS for vaccine exposure: (1) logistic regression treating the exposure status as binary yes or no; (2) Cox regression treating time to exposure as time-to-event. Coverage probability of the nominal 95% confidence interval for the exposure effect is used as the main measure of performance. The performance of the logistic regression PS depends largely on how the exposure data is generated. In contrast, the Cox regression PS consistently performs well across the different data generating mechanisms that we have considered. In addition, the Cox regression PS allows adjusting for potential time-varying confounders such as season of the year or exposure to additional vaccines. The application of the Cox regression PS is illustrated using data from a recent study of the safety of pandemic H1N1 influenza vaccine during pregnancy

Comparative Proteomic Analysis of saccharopolyspora spinosa SP06081 and PR2 strains reveals the differentially expressed proteins correlated with the increase of spinosad yield

<p>Abstract</p> <p>Background</p> <p><it>Saccharopolyspora spinosa </it>produces the environment-friendly biopesticide spinosad, a mixture of two polyketide-derived macrolide active ingredients called spinosyns A and D. Therefore considerable interest is in the improvement of spinosad production because of its low yield in wild-type <it>S. spinosa</it>. Recently, a spinosad-hyperproducing PR2 strain with stable heredity was obtained from protoplast regeneration of the wild-type <it>S. spinosa </it>SP06081 strain. A comparative proteomic analysis was performed on the two strains during the first rapid growth phase (RG1) in seed medium (SM) by using label-free quantitative proteomics to investigate the underlying mechanism leading to the enhancement of spinosad yield.</p> <p>Results</p> <p>In total, 224 proteins from the SP06081 strain and 204 proteins from the PR2 strain were unambiguously identified by liquid chromatography-tandem mass spectrometry analysis, sharing 140 proteins. A total of 12 proteins directly related to spinosad biosynthesis were identified from the two strains in RG1. Comparative analysis of the shared proteins revealed that approximately 31% of them changed their abundance significantly and fell in all of the functional groups, such as tricarboxylic acid cycles, glycolysis, biosynthetic processes, catabolic processes, transcription, translation, oxidation and reduction. Several key enzymes involved in the synthesis of primary metabolic intermediates used as precursors for spinosad production, energy supply, polyketide chain assembly, deoxysugar methylation, and antioxidative stress were differentially expressed in the same pattern of facilitating spinosad production by the PR2 strain. Real-time reverse transcriptase polymerase chain reaction analysis revealed that four of five selected genes showed a positive correlation between changes at the translational and transcriptional expression level, which further confirmed the proteomic analysis.</p> <p>Conclusions</p> <p>The present study is the first comprehensive and comparative proteome analysis of <it>S. spinosa </it>strains. Our results highlight the differentially expressed proteins between the two <it>S. spinosa </it>strains and provide some clues to understand the molecular and metabolic mechanisms that could lead to the increased spinosad production yield.</p

In Children with Nonalcoholic Fatty Liver Disease, Zone 1 Steatosis is Associated with Advanced Fibrosis

Background & Aims Focal zone 1 steatosis, although rare in adults with nonalcoholic fatty liver disease (NAFLD), does occur in children with NAFLD. We investigated whether focal zone 1 steatosis and focal zone 3 steatosis are distinct subphenotypes of pediatric NAFLD. We aimed to determine associations between the zonality of steatosis and demographic, clinical, and histologic features in children with NAFLD. Methods We performed a cross-sectional study of baseline data from 813 children (age <18 years; mean age, 12.8 ± 2.7 years). The subjects had biopsy-proven NAFLD and were enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network. Liver histology was reviewed using the Nonalcoholic Steatohepatitis Clinical Research Network scoring system. Results Zone 1 steatosis was present in 18% of children with NAFLD (n = 146) and zone 3 steatosis was present in 32% (n = 244). Children with zone 1 steatosis were significantly younger (10 vs 14 years; P < .001) and a significantly higher proportion had any fibrosis (81% vs 51%; P < .001) or advanced fibrosis (13% vs 5%; P < .001) compared with children with zone 3 steatosis. In contrast, children with zone 3 steatosis were significantly more likely to have steatohepatitis (30% vs 6% in children with zone 1 steatosis; P < .001). Conclusions Children with zone 1 or zone 3 distribution of steatosis have an important subphenotype of pediatric NAFLD. Children with zone 1 steatosis are more likely to have advanced fibrosis and children with zone 3 steatosis are more likely to have steatohepatitis. To achieve a comprehensive understanding of pediatric NAFLD, studies of pathophysiology, natural history, and response to treatment should account for the zonality of steatosis

Application of Al/B/Fe2O3 Nano Thermite in Composite Solid Propellant

Hydroxyl-terminated polybutadiene (HTPB) propellant were prepared with different content of Al/B/Fe2O3 nano thermite, and the mechanical, thermal and energetic performances were studied. Al/B/Fe2O3 nano thermite exhibited good compatibility with HTPB and dioctyl sebacate (DOS) through differential scanning calorimetry (DSC) tests. Mechanical experiments show that the mechanical properties of HTPB propellant could be improved by the addition of a small quantity of Al/B/Fe2O3 nano thermite, compared with the absence of Al/B/Fe2O3 nano thermite. For example, with the addition of 3% Al/B/Fe2O3 nano thermite, the tensile strength and elongation of propellant had the increase of 15.3% and 32.1%, respectively. Thermal analysis indicated that the decomposition of ammonium perchlorate (AP) in HTPB propellant could be catalyzed by Al/B/Fe2O3 nano thermite, the high-temperature exothermic peak of AP was shifted to lower temperature by 70.8 °C when the content of Al/B/Fe2O3 nano thermite was 5%, and the heat released was enhanced by 70%. At the same time, the heat of explosion of HTPB propellant could also be enhanced by the addition of Al/B/Fe2O3 nano thermite. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th November 2015; Revised: 4th December 2015; Accepted: 30th December 2015 How to Cite: Deng, J., Li, G., Shen, L., Luo, Y. (2016). Application of Al/B/Fe2O3 Nano Thermite in Composite Solid Propellant. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1): 109-114. (doi:10.9767/bcrec.11.1.432.109-114) Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.432.109-11

Mechanical Properties of HTPE/Bu-NENA Binder and the Kinetics of Bu-NENA Evaporation

The correlation between the mechanical properties of hydroxyl-terminated polyether (HTPE)/N-butyl-N-(2-nitroxyethyl)nitramine (Bu-NENA) binders with different plasticization ratios (pl/po), varied from 0.9 to 1.5, have been studied. The very early stage of evaporation of Bu-NENA from the HTPE/Bu-NENA binder, with a pl/po ratio of 1.2, has been investigated. The results revealed that the pl/po ratio has strong influences on the mechanical properties. When the pl/po ratio was 1.2, the mechanical properties of the HTPE/Bu-NENA binder were satisfactory, the maximum tensile strength and the elongation at break being 2.39 MPa and 93.27%, respectively. The evaporation rate constant of Bu-NENA from HTPE/Bu-NENA binder with a pl/po ratio of 1.2 increased from 0.31·10–5 to 2.32·10–5 s–1 as the temperature was increased from 50 to 90 °C. The value of the activation energy of evaporation was 51.47 kJ/mol and its pre-exponential factor was 6.14·102 s–1

Synthesis and Characterization of Multifunctional Two-Component Waterborne Polyurethane Coatings: Fluorescence, Thermostability and Flame Retardancy

Fluorescent and flame-retardant two-component waterborne polyurethane coatings were synthesized using 1,5-dihydroxy naphthalene, a halogen-free polyphosphate and a hydrophilic curing agent, and their properties were systematically characterized. The average particle sizes and zeta potential values were below 170 nm and −30 mV. Meanwhile, the multifunctional two-component waterborne polyurethane coatings had strong fluorescence intensities. When comparing with the coatings with 0.5 wt % 1,5-dihydroxy naphthalene, the coatings with 1.0 wt % 1,5-dihydroxy naphthalene had a stronger microphase separation. Interestingly, the thermostability of the multifunctional coatings was remarkably improved through 1.0 wt % 1,5-dihydroxy naphthalene, and besides it belonged to nonflammable materials. Additionally, all of the coating films passed the solvent resistance testing. These samples with different amounts of 1,5-dihydroxy naphthalene are environmental friendly, especially applications that require transparent and fluorescent coatings

Oxidation mechanism of perfluorooctanoic acid-functionalized aluminum metastable intermolecular composites regulated by Preignition reactions interface fuel-oxidizer ratio

PFOA-functionalized Al Metastable Intermolecular Composites (MICs) refer to the system using aluminum nanoparticles as fuel and PFOA as oxidant. Aluminum is the most widely used metal fuel in energetic materials. Al NPs are widely used because they are relatively cheap, easily accessible, nontoxic, excellent in thermodynamic performance. Fluorine has higher density and stronger oxidation capacity than oxygen element. PFOA has a high fluorine content (68.8%). PFOA-functionalized Al MICs mixed the high calorific value of aluminum and oxidizing fluorine in nano-sized. In this paper, PFOA-functionalized Al MICs with different PIR interface fuel-oxidizer ratios were prepared by electrostatic spray. The microstructure of the MICs was characterized by TEM. PFOA is uniformly coated on the Al NPs. The composition of MIC system was analyzed by FTIR and XRD. The combustion performance of MICs was tested by laser ignition, and the decomposition mechanism of PFOA-functionalized Al MICs was studied by DSC-TG. Results show that the exothermic process and activation energy of MICs are affected by the Preignition reactions (PIR) interface fuel-oxidizer ratios. The ignition and combustion processes of MICs and pressurization rate increase with the increase of oxidizer, and the burning rate decreases with the increase of oxidizer

Research on Mechanical Properties and Sensitivity of a Novel Modified Double-Base Rocket Propellant Plasticized by Bu-NENA

The research and development of rocket propellants with a high solid content and superior mechanical and security performance is urgently needed. In this paper, a novel extruded modified double-base (EMDB) rocket propellant plasticized by N-butyl-N-nitratoethyl nitramine (Bu-NENA) was prepared to overcome this challenge. The results indicated that Bu-NENA decreased the mechanical sensitivity successfully, contributing to the mechanical properties against traditional nitroglycerin (NG) based EMDB propellants, while hexogen (RDX), which is beneficial to propellant energy, was not conducive to the elongation and sensitivity of the propellants. By contrast with the blank group (NG-based EMDB propellant, R0), the elongation of the optimized propellant at −40 °C was promoted by 100% from 3.54% to 7.09%. Moreover, the β-transition temperature decreased from −33.8 °C to −38.1 °C due to superior plasticization by Bu-NENA, which represents a better toughness. The friction sensitivity dropped by 100% from 46% to 0%. Simultaneously, the height for 50% probability of explosion (H50) increased by 87.2% from 17.2 cm to 32.2 cm. The results of this research could be used to predict a potential prospect in tactical weapons