Geometric Concentrations Research Articles

Thermo-economic optimization of a hybrid photovoltaic and thermoelectric power generator using overall performance index

A thermo-economic assessment of a hybrid concentrated photovoltaic–thermoelectric power generator (CPV–TEG) is performed based on the first law of thermodynamics and principles of costing. This study aims at estimating the optimum water-cooled CPV–TEG design parameters that yield the maximum overall performance. The influence of key parameters (such as direct normal irradiance (DNI), geometric concentration, thermoelectric figure of merit, temperature ratio of thermoelectric junction and heat sink thermal resistance) and their significance on the performance and cost of the system is examined. A performance measure known as the overall performance index (OPI) is used to evaluate the optimum design of the CPV–TEG system operating within the limits of allowable cell temperatures. OPI can incorporate several performance indicators that are crucial for performance estimation of a hybrid system by using a mass coefficient for each indicator based on its priority in the overall system performance. OPI accounts for three performance indicators of the CPV–TEG system, namely: energy efficiency, cost of the solar receiver (COSR) and levelized cost of energy (LCOE). The variation of the OPI provides an indication of the performance of the hybrid system under different design parameters and the selection of the appropriate design of the system to be at a point where the OPI is a maximum. Two scenarios are considered such that different mass coefficients are assigned to the performance indicators when evaluating the system performance. In the first scenario (performance case), energy efficiency is given the highest priority while for the second scenario (economic case), the cost of the solar receiver (CPV–TEG system) is given more emphasis. Optimization is performed for the water-cooled CPV–TEG design such that the PV temperature is kept below the maximum allowable cell temperature of 100 °C. LCOE of 0.0392 $ kWh−1 was obtained with an optimum OPI of 94.7% for the economic case.

CFD based simulation of indoor radon distribution from the use of different brands of decorative glazed tiles made in China

ABSTRACT The radon exhalation rates of the surface of 10 different brands of glazed tiles made in China are measured and assessed. The experimental results reveal that the values of radon exhalation rate from the surface of glazed tiles are in the range of 0.36–2.52 Bq·m2 h−1, with a mean of 1.48 Bq·m2 h−1. These measurements obtained in this study are much lower than the typical radon exhalation rate international reference value of soil, and are also within the range of the reported literatures. Meanwhile, these data are taken as input parameters of computational fluid dynamics (CFD) model for simulation comparative study. The different plane distribution of radon from the use of different brands of glazed tiles in the model residential room is simulated. The simulation results show that the distribution of radon concentration in different XY plane is un-even, and the values of radon concentrations in XY plane is decreasing with the increase of z height. Deducting the contribution of the worldwide typical outdoor radon concentration, the maximum mean radon concentration at z = 0.5 m height was found to be 6.03 Bq·m−3 in Brand ‘B.H’ which accounts for 13.40% of the worldwide geometric mean indoor radon concentration. Combined with the measurement and simulation results, it can be known that the use of glazed tiles is not the main source of indoor radon, but glazed tile with lower radon exhalation rate is still needed for health purpose.

Solar Parabolocilindrical Installations, Constructive Features and Calculation of Individual Parameters

The article gives a brief description of a solar parabolic-cylindrical installation and its main element, an optical concentrator. The analysis is based on the most simplified and sufficiently accurate methodology for calculating the coefficient of geometric concentration of parabolic-cylindrical mirrors. The cases of an ideal parabolic-cylindrical concentrator having a small aperture are considered. A variant of calculating the concentration coefficient of a parabolic cylindrical concentrator for cylindrical and flat receivers is presented

PHOTOCATALYTIC SOLAR OXIDATION OF ACESULFAME-K. EFFECT OF INITIAL pH, CATALYST DOSE AND OXIDANT CONCENTRATION

Aqueous acesulfame-K was oxidized in a pilot solar photocatalytic reactor, equipped with a compound parabolic collector (CPC). The reactor has an area of 0.40 m2 of CPC collectors with geometrical concentration ratio of 1 and a simple mechanical configuration. The experiments of photocatalytic oxidation of acesulfame-K were performed by treating 2 L of water with an initial concentration of 15 mg/L. The photocatalyst used was P25 (Aeroxide TiO2) from Evonik. One of the goals of the research work was to find a set of conditions to efficiently remove this emerging concern pollutant. Results allowed proposing a set of reaction conditions that lead to a high removal of acesulfame-K. In addition, the experimental design allowed determining the effect of initial pH as well as the impact of initial concentrations of photocatalyst and chemical oxidant. The removal efficiency of acesulfame-K and related UV-absorbing species reached values up to 96-99 % and there was not a quantifiable amount of intermediate products (analyzed as UV absorbing species). Despite reaction time was fixed in 3 h for all the experiments, oxidation efficiencies higher than 95 % were reached at 2 h of reaction or even before.

Monte-Carlo optical model coupled with Inverse Adding-Doubling for Building Integrated Photovoltaic smart window design and characterisation

Building Integrated Photovoltaic (BIPV) glazings are promising technologies with the benefits of electricity generation, solar shading and building energy savings. A new approach is to integrate BIPV windows with thermotropic materials such as Hydroxypropyl Cellulose (HPC) hydrogel, which offers adaptive advantages for the systems to respond to time-varying weather conditions but also enhances the PV electricity generation. To design such systems, knowledge of the temperature-dependent scattering properties of the selected thermotropic materials is of significance. In this study, a Building Integrated Photovoltaic (BIPV) smart window system consisting of a thermotropic membrane synthesised using HPC and gellan gum gelling agent for electricity generation and also solar control has been designed and investigated. An advanced optical model, which combines a Monte-Carlo ray-tracing technique with an Inverse Adding-Doubling (IAD) method, has been developed for characterising the thermotropic membrane in terms of angular scattering distribution under various membrane temperatures and HPC concentrations. Then the developed optical model has been validated by comparison with experimental measurements. Subsequently, the validated optical model has been used to design and optimise the proposed BIPV smart window. The effects of HPC concentration, geometric concentration ratio, thermotropic membrane thickness and glass refractive index on PV power outputs have been evaluated. Finally, a prototype of the BIPV smart window with a 6 wt% HPC membrane has been manufactured and tested under indoor conditions. From the experimental tests, it was found that the total transmittance of the double-pane glass sample with a 6 wt% HPC membrane layer decreases from approximately 90%to 14%, when the membrane temperature increases from 27 °C to 56 °C. The measured short-circuit current for the prototype BIPV smart window is up to 1.15 times higher than that of its counterpart system with a similar PV area but no membrane.

Optimization of the focusing characteristics of Fresnel zone plates fabricated with a femtosecond laser

In this research, amplitude Fresnel zone plates (FZPs) were fabricated on fused silica glass with femtosecond laser. The focusing characteristics including focal length, diffraction efficiency, geometric concentrator ratio, spot energy uniformity, depth of focus and resolution were studied by simulations and experiments. To optimize the focusing characteristics of FZP, we proposed an optimized machining process, an extended FZP and an fractal FZP. The optimized machining process increased the diffraction efficiency of the amplitude FZP from 6.96% to 8.14%, the extended FZP broke through the limit of minimum line width in processing and improved the resolution, and the fractal FZP increased the focus depth from 4 mm to 10 mm. In addition, we wrote a FZP on the end face of multi mode fiber, the divergent annular beam converged and formed an focus ring at the focal plane. This research will provide broad applications in fiber tweezers, beam coupling and optical communication.

Stretchable micro-scale concentrator photovoltaic module with 15.4% efficiency for three-dimensional curved surfaces

Stretchable photovoltaics are emerging power sources for collapsible electronics, biomedical devices, and buildings and vehicles with curved surfaces. Development of stretchable photovoltaics are crucial to achieve rapid growth of the future photovoltaic market. However, owing to their rigidity, existing thin-film solar cells based predominantly on silicon, compound semiconductors, and perovskites are difficult to apply to 3D curved surfaces, which are potential real-world candidates. Herein, we present a stretchable micro-scale concentrator photovoltaic module with a geometrical concentration ratio of 3.5×. When perfectly fitted on a 3D curved surface with a sharp curvature, the prototype module achieves an outdoor power conversion efficiency of 15.4% and the daily generated electricity yield improves to a maximum of 190% relative to a non-concentration stretchable photovoltaic module. Thus, this module design enables high areal coverage on 3D curved surfaces, while generating a higher electricity yield in a limited installation area.

Prediction of spot weld fatigue life using finite element approach

Resistant spot welding is predominantly used in automotive industry for joining sheet metal. Mostly automobile fatigue failure occurs in and around spot welding (80%). So, accurate prediction of the deformation, stresses and fatigue life of spot weld is necessary. In this work finite element model of spot weld and experimental study of coach peel test of spot welded low carbon steel sheets are presented. The property change in various zones of spot weld is found by nano-indentation test followed by inverse finite element modelling. Spot weld failure happens at the interface between nugget and heat affected zone due to the geometric stress concentration and property change that occurs during the welding process. Solid elements are successful in capturing the geometric stress concentration, but they increase the simulation cost and hence a model with combined shell and solid elements is used. For nugget solid elements are used and tore present all other parts of spot weld shell elements are used. Tensile and fatigue tests on coach peel specimen are done as per ASTM standardD903-98. The simulation results are found to be in close agreement with experimental results.

Vitamin D and Vitamin K Concentrations in Human Brain Tissue Are Influenced by Freezer Storage Time: The Memory and Aging Project

BackgroundVitamins D and K, which are present in human brain, may have a role in neurodegenerative disease. ObjectivesGiven the interest in measuring nutrient concentrations in archived brain samples, it is important to evaluate whether freezer storage time affects these concentrations. Therefore, we evaluated differences in vitamin D and vitamin K concentrations in human brain samples stored for various lengths of time. MethodsPostmortem brain samples were obtained from 499 participants in the Rush Memory and Aging Project (mean age 92 y, 72% female). Concentrations of vitamins D and K and their metabolites were measured in 4 regions (midtemporal cortex, midfrontal cortex, cerebellum, anterior watershed white matter) using LC-MS/MS and HPLC, respectively. The predominant forms were 25-hydroxycholecalciferol [25(OH)D3] and menaquinone-4 (MK4). ANOVA was used to determine if concentrations differed according to storage time. ResultsThe geometric mean of the mean 25(OH)D3 concentration (across 4 regions) in brains stored for 1.1 to 6.0 y did not differ from that in brains stored ≤1.0 y (all P ≥ 0.37), whereas 25(OH)D3 in brains stored >6.0 y was 31–40% lower (P ≤ 0.003). MK4 had similar results, with the geometric mean MK4 concentration in the brains stored ≥9.0 y being 48–52% lower than those in brains stored ≤1.0 y (P ≤ 0.012). The 25(OH)D3 and MK4 concentrations were positively correlated across all 4 regions (all Spearman ρ ≥ 0.79, P < 0.001). Conclusions25(OH)D3 and MK4 appear to be stable in brain tissue from older adults stored at -80°C for up to 6 and 9 y, respectively, but not longer. Freezer storage time should be considered in the design and interpretation of studies using archived brain tissue.

121. A Respiratory Syncytial Virus Prefusion F Protein (RSVPreF3) Candidate Vaccine Administered in Older Adults in a Phase I/II Randomized Clinical Trial Is Immunogenic

BackgroundRSV causes significant disease burden in older adults, since reinfections are common and may lead to severe disease presentations while only supportive treatment is available. We present immunogenicity of different formulations of an investigational vaccine (RSVPreF3) in young and older adults.MethodsThis is a phase I/II, placebo-controlled, multi-country trial (NCT03814590). Healthy adults aged 18–40 years were randomized 1:1:1:1 to receive 2 doses of either Low-, Medium- or High-dose of RSVPreF3 non-adjuvanted vaccine or placebo, 2 months apart. Following favorable safety outcomes, adults aged 60–80 years were randomized 1:1:1:1:1:1:1:1:1:1 in a 2-step staggered manner to receive 1 of the 9 RSV vaccine formulations containing Low-, Medium- or High-dose of RSVPreF3, non-adjuvanted or adjuvanted with AS01E or AS01B, or placebo (same schedule). Humoral and cellular-mediated immune responses are assessed before and after each dose; results up to 1 month post-dose 1 are shown here.ResultsOf 48 adults aged 18–40 years and 1005 aged 60–80 years included in the exposed set, 42 and 933, respectively, were part of per-protocol set at 1 month post-dose 1. RSVPreF3 IgG geometric mean antibody concentrations were 8.4–13.5 and 7.2–12.8 fold-higher at 1 month post-dose 1 vs baseline in the 18–40- and 60–80-year-old vaccinees, respectively (Fig 1A). RSV-A neutralization activity significantly increased in all RSV vaccinees, geometric mean antibody titers being 7.5–13.7 and 5.6–9.9 fold-higher in 18–40- and 60–80-year-olds, respectively, at 1 month post-dose 1 vs baseline (Fig 1B). Geometric mean ratios of the fold increase between RSVPreF3 IgG antibody concentrations and RSV-A neutralizing antibody titers ranged between 0.9–1.1 in 18–40-year-old and 1.3–1.5 in 60–80-year-old vaccinees. A robust RSVPreF3-specific CD4+ T-cell response was elicited at 1 month post-dose 1 vs baseline in both 18–40- and 60–80-year-olds (Fig 2).Figure 1. RSVPreF3 IgG geometric mean antibody concentrations (GMCs, enzyme-linked immunosorbent assay, panel A), RSV-A neutralizing geometric mean antibody titers (GMTs, neutralization assay, panel B) Figure 2. RSVPreF3-specific CD4+ T-cells identified as expressing ≥2 markers among IL2, CD40L, TNF-□, IFN-□ (intracellular cytokine staining assay) ConclusionOne dose of RSVPreF3 candidate vaccine boosted humoral and cellular immune responses in all vaccinees. In older adults, higher humoral response, mostly neutralizing, was observed with increased RSVPreF3 antigen dosage and a tendency of higher cellular response was observed after adjuvanted formulations.FundingGlaxoSmithKline Biologicals SADisclosuresJavier Ruiz Guiñazú, MD MSc, GSK group of companies (Employee, Shareholder) Jelena Tica, PhD, GSK group of companies (Employee, Shareholder) Charles P. Andrews, MD, GSK group of companies (Scientific Research Study Investigator) Charles Fogarty, MD, GSK group of companies (Grant/Research Support) Edward Kerwin, MD, Amphastar (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)AstraZeneca (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Boehringer Ingelheim (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Chiesi (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Cipla (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)GSK group of companies (Employee, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Mylan (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Novartis (Employee, Advisor or Review Panel member, Research Grant or Support, Speaker’s Bureau)other around 40 pharmaceutical companies (Other Financial or Material Support, conducted multicenter clinical research trials)Pearl (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Sunovion (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Theravance (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau) Isabel Leroux-Roels, MD PhD, GSK group of companies (Scientific Research Study Investigator) Corinne Vandermeulen, MD PhD, GSK group of companies (Other Financial or Material Support, My university only received Grant/Research Support) Marie-Pierre David, MSc, GSK group of companies (Employee, Shareholder) Nancy Dezutter, PhD, PharmD, RPh, GSK group of companies (Employee, Shareholder) Nathalie De Schrevel, PhD, GSK group of companies (Employee) Laurence Fissette, MSc, GSK group of companies (Employee) Narcisa Mesaros, MD, MSc, GSK group of companies (Employee)

Characterization of an angular domain fluorescence optical projection tomography system for mesoscopic lymph node imaging.

Transmittance and fluorescence optical projection tomography can offer high-resolution and high-contrast visualization of whole biological specimens; however, applications are limited to samples exhibiting minimal light scattering. Our previous work demonstrated that angular-domain techniques permitted imaging of ∼1cm diameter noncleared lymph nodes because of their low scattering nature. Here, an angle-restricted transmittance/fluorescence system is presented and characterized in terms of geometric and fluorescence concentration reconstruction accuracy as well as spatial resolution, depth of focus, and fluorescence limits of detection. Using lymph node mimicking phantoms, results demonstrated promising detection and localization capabilities relevant for clinical lymph node applications.

Compensated compactness and corrector stress tensor for the Einstein equations in $\mathbb T^2$ symmetry

We consider the Einstein equations in \mathbb T^2 symmetry, either for vacuum spacetimes or coupled to the Euler equations for a compressible fluid, and we introduce the notion of \mathbb T^2 areal flows on \mathbb T^3 with finite total energy. By uncovering a hidden structure of the Einstein equations, we establish a compensated compactness framework which allows us to solve the global evolution problem for vacuum spacetimes as well as for self-gravitating compressible fluids. We study the stability and instability of such flows and prove that, when the initial data are well-prepared, any family of \mathbb T^2 areal flows is sequentially compact in a natural topology. In order to handle general initial data we propose a ‘‘relaxed’’ notion of \mathbb T^2 areal flows endowed with a corrector stress tensor (as we call it) which is a bounded measure generated by geometric oscillations and concentrations propagating at the speed of light. This generalizes a result for vacuum spacetimes in: Le Floch B. and P. G. LeFloch, Arch. Rational Mech. Anal. 233 (2019), 45–86.

Graphene as a pre-illumination cooling approach for a concentrator photovoltaic (CPV) system

The concentrator photovoltaic (CPV) system has a high potential in increasing the power output, propelling further the concentration ratio generating excessive heat that significantly deteriorates the solar cell efficiency and reliability. To thoroughly exploit graphene as a pre-illumination cooling technique for a solar cell, we experimentally characterized screen printed graphene coating (GC) physicochemical characterizations to observe the attenuation of light across a wide wavelength range with different GC thicknesses on a low iron-glass. The thermal and electrical characterizations were further executed to observe the performance of GC on a concentrated CPV system. Based on these comprehensive experimental characterizations, the concept of utilizing graphene as a neutral density (ND) filter for focal spot CPV system is shown to reduce the device temperature significantly by 20% and 12% for GC6.3 (6.3 μm thickness) and GC2.2 (2.2 μm thickness) in comparison with the infrared filter, respectively. It has been observed that GC6.3 increased the cell efficiency by about 12% at 8 suns compared to the base case at 400 W/m2 producing 7 suns. It has been ascertained that the introduction of graphene as the ND filter component improved the solar cell efficiency instead of just reducing the geometrical concentration ratio. Further, even the most susceptible single-junction solar cell under a concentration ratio of ≈20 suns with no cooling aid has shown an excellent cell efficiency. Therefore, our approach envisages its application for non-CPV and high and ultrahigh CPV system incorporated with a triple-junction solar cell eliminate the use of external heat sinks or other cooling arrangements.

Immunogenicity of pneumococcal vaccination in HIV infected individuals: A systematic review and meta-analysis

BackgroundThe objective of this systematic review and meta-analysis was to summarise the literature regarding the immunogenicity of pneumococcal conjugate vaccines (PCV) and pneumococcal polysaccharide vaccines (PPSV) in adult people living with HIV (PLWH) in the era of advanced combination antiretroviral therapy (cART).MethodsThe systematic review protocol was published online (PROSPERO ID: CRD 42020153137). We searched Medline (Ovid), EMBASE (Ovid), and the Global Health Library for publications from 2000 to June 11, 2020. We included all studies in adult PLWH that reported vaccine immunogenicity outcomes. The primary outcome was seroconversion rate (SCR) after PCV, PPSV and PCV/PPSV combined. For random-effects meta-analysis, we included studies defining SCR as a ≥ 2-fold increase in IgG from baseline, and reporting SCR for serotypes 6B, 14, or overall SCR, 1–3 months after vaccination.FindingsOur search identified 1597 unique studies, of which 115 were eligible for full-text assessment. Of these, 39 met the inclusion criteria (11 RCTs; 28 cohort studies). A high degree of heterogeneity was observed. Nineteen studies were included in the meta-analysis. Pooled overall SCRs were 42% (95% CI 30–56%), 44% (95% CI 33–55%) and 57% (95% CI 50–63%) for PLWH who received PPSV, PCV or a combination of PCV/PPSV, respectively. Compared to PPSV alone, a combination of PCV/PPSV yielded higher SCRs (OR 2.24 95% CI 1.41- 3.58), whereas we did not observe a significant difference in SCR between PCV and PPSV23 alone. There were no statistically significant differences in geometric mean post-vaccination antibody concentrations between vaccination schedules. Vaccination at higher CD4 cell counts improved immunogenicity in 8/21 studies, especially when PCV was administered. No studies assessed the long-term immunogenicity of PCV followed by PPSV23. Quality of evidence ranged from poor (n = 19) to good quality (n = 7). A limited number of pneumococcal serotypes was assessed in the majority of studies.InterpretationWe show that the recommended immunisation schedule consisting of a combination of PCV13/PPSV23, is immunogenic in PLWH in the era of advanced cART. However, the durability of this vaccination schedule remains unknown and must be addressed in future research. Vaccination with PCV should be delayed until immunological recovery (CD4>200) in recently diagnosed PLWH for optimal immunogenicity. The evidence gathered here supports wide implementation of the combination of PCV/PPSV23 for all PLWH. We recommend reassessment of this strategy once higher-valent PCVs become available.FundingHMGG is funded by a public research grant of ZonMw (project number 522004005).

Gestational exposure to organophosphate esters (OPEs) and maternal blood pressure during pregnancy: The HOME Study

Background: After the phase-out of polybrominated diphenyl ethers, exposure to organophosphate esters (OPEs), which are potential endocrine disruptors, is ubiquitous. No study has examined the associations between gestational exposure to OPEs and blood pressure and the risk of pregnancy-induced hypertensive diseases.Methods: We used data from 333 women who had liveborn singletons without congenital abnormalities in the Health Outcomes and Measures of the Environment (HOME) Study, a prospective birth cohort. We quantified maternal urinary OPE metabolites at 16 weeks of gestation. Outcomes included the highest maternal blood pressure measurement at ≥20 weeks of gestation and pregnancy-induced hypertensive diseases (gestational hypertension, preeclampsia, and eclampsia) from medical chart review. We used linear regression and modified Poisson regression with covariate adjustment to estimate the associations of exposure with blood pressure and the risk of pregnancy-induced hypertensive diseases, respectively.Results: Diphenyl phosphate (DPHP) had the highest geometric mean urinary concentrations (1.65 µg/g creatinine), followed by bis(1,3-dichloro-2-propyl) phosphate (BDCIPP; 0.76 µg/g creatinine), bis(2-chloroethyl) phosphate (BCEP; 0.70 µg/g creatinine), and dibutyl phosphate (DBUP; 0.25 µg/g creatinine). There were 29 (8.7%) women diagnosed with pregnancy-induced hypertensive diseases. Average systolic and diastolic blood pressure, measured at an average of 31 weeks gestation (range: 20-41), were 117±13 and 72±9 mmHg, respectively. None of the urinary OPE metabolites were significantly associated with the highest maternal blood pressure at ≥20 weeks of gestation, nor were they strongly associated with an increased risk of pregnancy-induced hypertensive diseases. The relative risk (RR; 95% confidence interval) of pregnancy-induced hypertensive diseases by a 10-fold increase in exposure was 1.31 (0.66, 2.59) for DPHP, 1.36 (0.51, 3.67) for BDCIPP, 0.63 (0.16, 2.39) for BCEP and 2.13 (0.78, 5.77) for DBUP.Conclusion: This study suggests no associations between maternal urinary OPE metabolite concentrations and blood pressure or an increased risk of pregnancy-induced hypertensive diseases during pregnancy.

Per- and Polyfluoroalkyl Substances (PFAS) Concentrations in Serum and Drinking Water in Pregnant Women from the Greater Cincinnati Area HOME Study

Background: The occurrence, fate, and transport of PFAS in the environment is understood, but the contribution of drinking water to serum PFAS concentrations in humans is poorly defined. Methods: We examined data from a prospective pregnancy and birth cohort (HOME Study) in Cincinnati, Ohio. We quantified PFOA and PFOS in sera of 227 pregnant women at 16 weeks gestation between 2003 and 2006. Tap water was collected from the participants’ homes within one month of blood collection. We mapped serum and tap water PFAS concentrations using ArcGIS and examined clustering via spatial hotspot analyses for each participant. Results: The median (range) of PFOA serum concentration in pregnant HOME Study participants between 2003-2006 was 5.4 (0.5-24.5) ng/ml, which is over twice the geometric mean serum concentration of 2.4 ng/l as measured in a representative sample of pregnant women in NHANES 2003 and 2004. Median PFOA drinking water concentrations in samples collected from participants’ homes were 3.7 ng/l in 2003, 4.5 ng/l in 2004, 6.4 ng/l in 2005 and 11.0 ng/l in 2006. For each doubling of water PFOA concentration, serum PFOA increased by 0.6 ng/l (95% CI: 0.02, 1.20) after adjusting for water source type (bottled/filtered vs tap water). For every doubling of water PFOS, serum PFOS increased 0.95 ng/l (95%CI: -0.10, 2.00).Conclusions: Drinking water is an important contributing source of PFAS exposure in pregnant women. This research adds to the literature, helping to delineate the relationship between drinking water and circulating serum concentrations of PFAS in pregnant women.The views expressed in this abstract are those of the authors and do not necessarily reflect the views or policies of the U.S. EPA.

Prenatal urinary phthalates and postpartum metabolic health in Women from Mexico City

Studies have reported associations between phthalates, a family of ubiquitous environmental contaminants, and metabolic complications of pregnancy, but no study has considered these outcomes beyond pregnancy. We examined associations of prenatal phthalates exposure with postpartum metabolic health biomarkers in the PROGRESS cohort.The longitudinal PROGRESS cohort includes 948 pregnant women recruited during the second trimester from 2007 to 2011. We quantified 15 phthalate metabolites from spot urines collected during the second and third trimesters. Maternal metabolic health biomarkers were fasting blood measures of glycemia [glucose, insulin, %glycated hemoglobin (HbA1C%)] and lipids (total, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) cholesterol, and triglycerides], collected at 48 and 72 months postpartum. We used linear mixed models, weighted quantile sum regression, and Bayesian Kernel Machine Regression to estimate associations of geometric mean urinary phthalate metabolite concentrations (between 2nd/3rd trimesters) and metabolic health biomarkers.In multivariable-adjusted linear mixed models, each doubling of mean urinary mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) was associated with 0.12 uIU/L greater plasma insulin (95%CI: 0.0, 0.25) and 0.06% greater HbA1C% (95%CI: 0.03, 0.09). Mixtures analyses indicated that phthalate mixtures were positively associated with plasma insulin and HbA1c% and MECPTP and diisobutyl phthalate metabolites were the primary drivers. Mediation analyses found that greater gestational weight retention (GWR) mediated 29% of the observed association between urinary MECPTP and plasma insulin. No mediation by GWR was observed for HbA1C%.We found that prenatal MECPTP concentrations were positively associated with plasma insulin and HbA1C% up to 72 months postpartum. In previous analyses of this cohort, we found that prenatal MECPTP was associated with greater GWR and blood pressure. Collectively, these findings suggest that exposure to di-2-ethylhexyl terephthalate, parent compound of MECPTP, may contribute to poorer metabolic health among women. GWR may be one mediator of later metabolic dysfunction; other underlying mechanisms and clinical implications are unknown.

Epidemiology of drinking water contaminants: inferring exposure through population biomarkers

Background: In using drinking water contamination as an exposure indicator for environmental epidemiology, it is important to know how important an exposure route is drinking water. If the water concentrations contribute a low proportion of total intake, they are of little value in etiological studies of that contaminant. But can nevertheless be of use if the goal of the study is the estimate the effect of the drinking water component specifically, for example to underpin setting drinking water standards. The main focus of this talk is a study of perfluoro-octanoic acid (PFOA) exposure where drinking water is the overwhelming route of exposure. Methods: In the Mid-Ohio Valley approximately 80,000 people were exposed to PFOA contaminated drinking water for many years and many health effects were studied in these “C8 studies”. Most of the exposure came from 6 district water supplies with varying degrees of contamination. Within each district the water distribution led to fairly uniform concentrations but these varied over time. Over 60,000 people provided blood samples and PFOA measures in serum provided another metric for assessing exposure by water distribution area which integrated intake for each community. Water concentrations and serum concentrations were both collected in these communities Results: Geometric mean serum concentrations for PFOA ranged from 10 to 200 ng/ml by district, reflecting differences in water concentration, and these mean values have been used to assess the evidence of associations with several outcomes including cholesterol and thyroid hormones. Discussion: PFOA has the advantage of a very long half life in serum, about 3 years. Food related intake is significant as an exposure route in most communities. Where the water concentrations are high enough to dominate exposure, biomonitoring offers an efficient alternative to water measurements to assess exposure, integrating intake over recent years. Keywords: Water, water quality, biomarkers, perfluoro-octanoic acid, environmental epidemiology

Notched fatigue of additive manufactured metals under axial and multiaxial loadings, Part I: Effects of surface roughness and HIP and comparisons with their wrought alloys

Additive manufacturing (AM) technology has grown significantly in recent years, as an alternative manufacturing technique to conventional fabrication methods. However, fatigue behavior of AM metals is still not well understood, limiting their applications for critical load carrying components. This is particularly true when component-like features such as geometrical stress concentrations such as notches exist, or complex service loading conditions such as shear or multiaxial stresses are present. In this work notched fatigue behavior of AM metals under axial, torsion, and combined axial-torsion loadings are investigated and contrasted with their wrought counterparts, using two common AM metals, Ti-6Al-4V and 17-4 PH stainless steel. Different post fabrication heat treatments and surface roughness conditions were included. Part I of this two-part publication presents the fatigue test results and comparative analyses. In Part II, both crack initiation (i.e. critical plane-based method) and crack growth (i.e. fracture mechanics-based method) approaches to life predictions are used for predictive analysis and comparisons with the experimental results presented in part I.

Consumption of multiple micronutrients or small-quantity lipid-based nutrient supplements containing iodine at the recommended dose during pregnancy, compared with iron and folic acid, does not affect women's urinary iodine concentration in rural Malawi: a secondary outcome analysis of the iLiNS DYAD trial.

Inadequate iodine intake during pregnancy increases the risk of neonatal morbidity and mortality. We aimed to evaluate whether prenatal supplements containing iodine affect urinary iodine concentrations (UIC) of pregnant women in Malawi. A randomised controlled trial. Pregnant women (n 1391) were assigned to consume 60 mg/d Fe and 400 µg/d folic acid (IFA) or 18 vitamins and minerals including 250 µg/d iodine (MMN) or 20 g/d small-quantity lipid-based nutrient supplements (SQ-LNS) with similar nutrient contents as MMN group, plus macronutrients (LNS) until childbirth. In a sub-study (n 317), we evaluated group geometric mean urinary iodine concentration (UIC) (µg/L) at 36 weeks of gestation controlling for baseline UIC and compared median (baseline) and geometric mean (36 weeks) UIC with WHO cut-offs: UIC < 150, 150-249, 250-499 and ≥500 reflecting insufficient, adequate, above requirements and excessive iodine intakes, respectively. Mangochi District, Malawi. Women ≤20 weeks pregnant. Groups had comparable background characteristics. At baseline, overall median (Q1, Q3) UIC (319 (167, 559)) suggested iodine intakes above requirements. At 36 weeks, the geometric mean (95 % CI) UIC of the IFA (197 (171, 226)), MMN (212 (185, 243)) and LNS (220 (192, 253)) groups did not differ (P = 0·53) and reflected adequate intakes. In this setting, provision of supplements containing iodine at the recommended dose to pregnant women with relatively high iodine intakes at baseline, presumably from iodised salt, has no impact on the women's UIC. Regular monitoring of the iodine status of pregnant women in such settings is advisable. Clinicaltrials.gov identifier: NCT01239693.