Materials, Structures and Manufacturing: An Integrated Approach to Develop Expandable Structures

Membrane dominated space structures are lightweight and package efficiently for launch; however, they must be expanded (deployed) in-orbit to achieve the desired geometry. These expandable structural systems include solar sails, solar power arrays, antennas, and numerous other large aperture devices that are used to collect, reflect and/or transmit electromagnetic radiation. In this work, an integrated approach to development of thin-film damage tolerant membranes is explored using advanced manufacturing. Bio-inspired hierarchical structures were printed on films using additive manufacturing to achieve improved tear resistance and to facilitate membrane deployment. High precision, robust expandable structures can be realized using materials that are both space durable and processable using additive manufacturing. Test results show this initial work produced higher tear resistance than neat film of equivalent mass. Future research and development opportunities for expandable structural systems designed using an integrated approach to structural design, manufacturing, and materials selection are discussed

Identifying heterogeneous transgenerational DNA methylation sites via clustering in beta regression

This paper explores the transgenerational DNA methylation pattern (DNA methylation transmitted from one generation to the next) via a clustering approach. Beta regression is employed to model the transmission pattern from parents to their offsprings at the population level. To facilitate this goal, an expectation maximization algorithm for parameter estimation along with a BIC criterion to determine the number of clusters is proposed. Applying our method to the DNA methylation data composed of 4063 CpG sites of 41 mother–father-infant triads, we identified a set of CpG sites in which DNA methylation transmission is dominated by fathers, while at a large number of CpG sites, DNA methylation is mainly maternally transmitted to the offspring

Effects of phthalate exposure on asthma may be mediated through alterations in DNA methylation

Background: phthalates may increase the asthma risk in children. Mechanisms underlying this association remain to be addressed. This study assesses the effect of phthalate exposures on epigenetic changes and the role of epigenetic changes for asthma. In the first step, urine and blood samples from 256 children of the Childhood Environment and Allergic diseases Study (CEAS) were analyzed. Urine 5OH-MEHP levels were quantified as an indicator of exposure, and asthma information was collected. DNA methylation (DNA-M) was measured by quantitative PCR. In the screening part of step 1, DNA-M of 21 potential human candidate genes suggested by a toxicogenomic data were investigated in 22 blood samples. Then, in the testing part of step 1, positively screened genes were tested in a larger sample of 256 children and then validated by protein measurements. In step 2, we replicated the association between phthalate exposure and gene-specific DNA-M in 54 children in the phthalate contaminated food event. In step 3, the risk of DNA-M for asthma was tested in 256 children from CEAS and corroborated in 270 children from the Isle of Wight (IOW) birth cohort. Results: differential methylation in three genes (AR, TNF?, and IL-4) was identified through screening. Testing in 256 children showed that methylation of the TNF? gene promoter was lower when children had higher urine 5OH-MEHP values (??=??0.138, P?=?0.040). Functional validation revealed that TNF? methylation was inversely correlated with TNF? protein levels (??=??0.18, P?=?0.041). In an additional sample of 54 children, we corroborated that methylation of the TNF? gene promoter was lower when urine 5OH-MEHP concentrations were higher. Finally, we found that a lower methylation of 5?CGI region of TNF? was associated with asthma in 256 CEAS children (OR?=?2.15, 95% CI?=?1.01 to 4.62). We replicated this in 270 children from the IOW birth cohort study. Methylation of the CpG site cg10717214 was negatively associated with asthma, when children had ‘AA’ or ‘AG’ genotype of the TNF? single nucleotide rs1800610. Conclusions: effects of phthalate exposure on asthma may be mediated through alterations in DNA methylatio

Transgenerational and intergenerational epigenetic inheritance in allergic diseases

It has become clear that early life (including in utero exposures) is a key window of vulnerability during which environmental exposures can alter developmental trajectories and initiate allergic disease development. However, recent evidence suggests that there might be additional windows of vulnerability to environmental exposures in the parental generation before conception or even in previous generations. There is evidence suggesting that information of prior exposures can be transferred across generations, and experimental animal models suggest that such transmission can be conveyed through epigenetic mechanisms. Although the molecular mechanisms of intergenerational and transgenerationational epigenetic transmission have yet to be determined, the realization that environment before conception can alter the risks of allergic diseases has profound implications for the development of public health interventions to prevent disease. Future research in both experimental models and in multigenerational human cohorts is needed to better understand the role of intergenerational and transgenerational effects in patients with asthma and allergic disease. This will provide the knowledge basis for a new approach to efficient intervention strategies aimed at reducing the major public health challenge of these conditions.publishedVersio

DEVELOPMENT AND EVALUATION OF A TIE-DOWN SYSTEM FOR THE REDESIGNED F-SHAPE CONCRETE TEMPORARY BARRIER

Often, temporary barriers are used in applications where it is desired that their deflection during vehicular impact be limited. One such application is in the installation of temporary barriers placed adjacent to the edge of a concrete bridge deck in order to maximize lane width. Acceptable tie-down systems for temporary barriers have previously been developed, but there are concerns when the barriers and tie-down systems are used on bridges that are reconstructed in stages and where very little tolerance in barrier deflection is allowable. Therefore, a rigid tie-down system was developed that minimizes barrier deflections. For this system, the original Kansas temporary barrier was redesigned in order to strengthen the barrier around the tie-down holes and to standardize the barriers for use in adjacent states and in various temporary and tied-down configurations. The tie-down anchor system fastened the traffic-side of the barriers to the concrete bridge deck with three 29-mm (1.125-in.) diameter ASTM A307 anchor bolts with heavy hex nuts and 76-mm (3-in.) x 76-mm (3-in.) x 13-mm (0.5-in.) thick washers. The research study included one full-scale vehicle crash test, using a 3⁄4-ton pickup truck. The full-scale test, with an impact speed of 99.8 km/hr (62.0 mph) and an impact angle of 25.3 degrees, was conducted and reported in accordance with the requirements specified in the National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. The safety performance of the tie-down anchor system for use with concrete bridge decks and the redesigned F-shape temporary concrete barrier was determined to be acceptable according to the Test Level 3 (TL-3) evaluation criteria specified in NCHRP Report No. 350

Evaluating the efficacy of breastfeeding guidelines on long-term outcomes for allergic disease

Background: WHO guidelines advocate breastfeeding for six months, and EAACI recommends exclusive breastfeeding for 4-6 months. However, evidence for breastfeeding to prevent asthma and allergic disease is conflicting. We examined whether following recommended breastfeeding guidelines alters the long-term risks of asthma, eczema, rhinitis, or atopy.Methods: The effect of non-exclusive (0, >0-6, >6 months), and exclusive breastfeeding (0, >0-4, >4 months) on repeated measures of asthma (10, 18 years), eczema, rhinitis, and atopy (1-or-2, 4, 10,18 years) risks were estimated in the IoW cohort (n=1456) using log-linear models with generalised estimating equations. The Food Allergy and Intolerance Research (FAIR) cohort (n=988), also from the IoW, was examined to replicate results.Results: Breastfeeding (any or exclusive) had no effect on asthma and allergic disease in the IoW cohort. In the FAIR cohort, any breastfeeding for >0-6 months protected against asthma at 10 years (RR=0.50, 95%CI=0.32-0.79, p=0.003) but not other outcomes, while exclusive breastfeeding for >4 months protected against repeated rhinitis (RR=0.36, 95%CI=0.18-0.71, p=0.003). Longer breastfeeding was protective against late-onset wheeze in the IoW cohort.Conclusion: The protective effects of non-exclusive and exclusive breastfeeding against long-term allergic outcomes were inconsistent between these co-located cohorts, agreeing with previous observations of heterogeneous effects. Although breastfeeding should be recommended for other health benefits, following breastfeeding guidelines did not appear to afford consistent protection against long-term asthma, eczema, rhinitis or atopy. Further research is needed into the long-term effects of breastfeeding on allergic disease