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Sample records for defects prevention study

  1. National Birth Defects Prevention Study (NBDPS)

    MedlinePlus

    ... taking multivitamins before their pregnancy. [ Read Summary ] Air Pollution and Congenital Heart Defects Many pregnant women, especially ... air quality standards to limit the amount of pollution in our air, we still do not know ...

  2. Laterality defects in the national birth defects prevention study 1998-2007 birth prevalence and descriptive epidemiology

    USDA-ARS?s Scientific Manuscript database

    Little is known epidemiologically about laterality defects. Using data from the National Birth Defects Prevention Study (NBDPS), a large multi-site case-control study of birth defects, we analyzed prevalence and selected characteristics in children born with laterality defects born from 1998 to 2007...

  3. Maternal autoimmune disease and birth defects in the National Birth Defects Prevention Study.

    PubMed

    Howley, Meredith M; Browne, Marilyn L; Van Zutphen, Alissa R; Richardson, Sandra D; Blossom, Sarah J; Broussard, Cheryl S; Carmichael, Suzan L; Druschel, Charlotte M

    2016-11-01

    Little is known about the association between maternal autoimmune disease or its treatment and the risk of birth defects. We examined these associations using data from the National Birth Defects Prevention Study, a multi-site, population-based, case-control study. Analyses included 25,116 case and 9897 unaffected control infants with estimated delivery dates between 1997 and 2009. Information on autoimmune disease, medication use, and other pregnancy exposures was collected by means of telephone interview. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for birth defects with five or more exposed cases; crude ORs and exact 95% CIs were estimated for birth defects with three to four exposed cases. Autoimmune disease was reported by 373 mothers (279 case and 94 control mothers). The majority of birth defects evaluated were not associated with autoimmune disease; however, a statistically significant association between maternal autoimmune disease and encephalocele was observed (OR, 4.64; 95% CI, 1.95-11.04). Eighty-two mothers with autoimmune disease used an immune modifying/suppressing medication during pregnancy; this was associated with encephalocele (OR, 7.26; 95% CI, 1.37-24.61) and atrial septal defects (OR, 3.01; 95% CI, 1.16-7.80). Our findings suggest maternal autoimmune disease and treatment are not associated with the majority of birth defects, but may be associated with some defects, particularly encephalocele. Given the low prevalence of individual autoimmune diseases and the rare use of specific medications, we were unable to examine associations of specific autoimmune diseases and medications with birth defects. Other studies are needed to confirm these findings. Birth Defects Research (Part A) 106:950-962, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  4. Paternal occupation and birth defects: findings from the National Birth Defects Prevention Study

    PubMed Central

    Desrosiers, Tania A.; Herring, Amy H.; Shapira, Stuart K.; Hooiveld, Mariette; Luben, Tom J.; Herdt-Losavio, Michele L.; Lin, Shao; Olshan, Andrew F.

    2013-01-01

    Objectives Several epidemiologic studies have suggested that certain paternal occupations may be associated with an increased prevalence of birth defects in offspring. Using data from the National Birth Defects Prevention Study, we investigated the association between paternal occupation and birth defects in a case-control study of cases comprising over 60 different types of birth defects (n = 9998) and non-malformed controls (n = 4066) with dates of delivery between 1997 and 2004. Methods Using paternal occupational histories reported by mothers via telephone interview, jobs were systematically classified into 63 groups based on shared exposure profiles within occupation and industry. Data were analyzed using Bayesian logistic regression with a hierarchical prior for dependent shrinkage to stabilize estimation with sparse data. Results Several occupations were associated with an increased prevalence of various birth defect categories, including: mathematical, physical and computer scientists; artists; photographers and photo processors; food service workers; landscapers and groundskeepers; hairdressers and cosmetologists; office and administrative support workers; sawmill workers; petroleum and gas workers; chemical workers; printers; material moving equipment operators; and motor vehicle operators. Conclusions Findings from this study might be used to identify specific occupations worthy of further investigation, and to generate hypotheses about chemical or physical exposures common to such occupations. PMID:22782864

  5. Paternal occupation and birth defects: findings from the National Birth Defects Prevention Study.

    PubMed

    Desrosiers, Tania A; Herring, Amy H; Shapira, Stuart K; Hooiveld, Mariëtte; Luben, Tom J; Herdt-Losavio, Michele L; Lin, Shao; Olshan, Andrew F

    2012-08-01

    Several epidemiological studies have suggested that certain paternal occupations may be associated with an increased prevalence of birth defects in offspring. Using data from the National Birth Defects Prevention Study, the authors investigated the association between paternal occupation and birth defects in a case-control study of cases comprising over 60 different types of birth defects (n=9998) and non-malformed controls (n=4066) with dates of delivery between 1997 and 2004. Using paternal occupational histories reported by mothers via telephone interview, jobs were systematically classified into 63 groups based on shared exposure profiles within occupation and industry. Data were analysed using bayesian logistic regression with a hierarchical prior for dependent shrinkage to stabilise estimation with sparse data. Several occupations were associated with an increased prevalence of various birth defect categories, including mathematical, physical and computer scientists; artists; photographers and photo processors; food service workers; landscapers and groundskeepers; hairdressers and cosmetologists; office and administrative support workers; sawmill workers; petroleum and gas workers; chemical workers; printers; material moving equipment operators; and motor vehicle operators. Findings from this study might be used to identify specific occupations worthy of further investigation and to generate hypotheses about chemical or physical exposures common to such occupations.

  6. Maternal intake of vitamin E and birth defects, National Birth Defects Prevention Study, 1997–2005

    PubMed Central

    Gilboa, Suzanne M.; Lee, Kyung A.; Cogswell, Mary E.; Traven, Flavia K.; Botto, Lorenzo D.; Riehle-Colarusso, Tiffany; Correa, Adolfo; Boyle, Coleen A.

    2015-01-01

    Background In a recent study, high maternal periconceptional intake of vitamin E was found to be associated with risk of congenital heart defects (CHDs). To explore this association further, we investigated the association between total daily vitamin E intake and selected birth defects. Methods We analyzed data from 4,525 controls and 8,665 cases from the 1997–2005 National Birth Defects Prevention Study. We categorized estimated periconceptional energy-adjusted total daily vitamin E intake from diet and supplements into quartiles (referent, lowest quartile). Associations between quartiles of energy-adjusted vitamin E intake and selected birth defects were adjusted for demographic, lifestyle, and nutritional factors. Results We observed a statistically significant association with the third quartile of vitamin E intake (OR 1.17; 95% CI 1.01 – 1.35) and all CHDs combined. Among CHD sub-types, we observed associations with left ventricular outflow tract obstruction defects, and its sub-type, coarctation of the aorta and the third quartile of vitamin E intake. Among defects other than CHDs, we observed associations between anorectal atresia and the third quartile of vitamin E intake (OR 1.66; 95% CI 1.01 – 2.72) and hypospadias and the fourth quartile of vitamin E intake (OR 1.42; 95% CI 1.09 – 1.87). Conclusions Selected quartiles of energy-adjusted estimated total daily vitamin E intake were associated with selected birth defects. However, because these few associations did not exhibit exposure-response patterns consistent with increasing risk associated with increasing intake of vitamin E, further studies are warranted to corroborate our findings. PMID:24740457

  7. Birth defects, causal attributions, and ethnicity in the national birth defects prevention study.

    PubMed

    Case, Amy P; Royle, Marjorie; Scheuerle, Angela E; Carmichael, Suzan L; Moffitt, Karen; Ramadhani, Tunu

    2014-10-01

    In order to translate research findings into effective prevention strategies, it is important to understand people's beliefs about the causes of poor health outcomes. However, with the exception of knowledge and beliefs about folic acid supplementation, little is known regarding women's causal attributions women regarding birth defects. We employed Attribution Theory constructs to analyze open-text interview responses from 2,672 control mothers in the National Birth Defects Prevention Study who gave birth in 1997-2005. Common themes included use of alcohol, tobacco, illicit drugs, and medications during pregnancy. Stress and emotional upset were also suggested as possible causes of birth defects. Genetic- and heredity-related responses were more likely to be mentioned by Asian/Pacific Islander women compared to non-Hispanic Whites. Hispanic women were less likely to suggest several specific possible teratogens, such as paint, pesticides, or other chemicals, but were more likely to suggest events occurring during childbirth. Differences also emerged among ethnic groups for theoretical constructs, although most responses were categorized as controllable, changeable over time, and with an internal locus of causality.

  8. Maternal caffeine intake and risk of selected birth defects in the National Birth Defects Prevention Study.

    PubMed

    Browne, Marilyn L; Hoyt, Adrienne T; Feldkamp, Marcia L; Rasmussen, Sonja A; Marshall, Elizabeth G; Druschel, Charlotte M; Romitti, Paul A

    2011-02-01

    Caffeine intake is common during pregnancy, yet few epidemiologic studies have examined the association between maternal caffeine consumption and birth defects. Using data from the National Birth Defects Prevention Study (NBDPS), we examined the association between maternal caffeine consumption and anotia/microtia, esophageal atresia, small intestinal atresia, craniosynostosis, diaphragmatic hernia, omphalocele, and gastroschisis. The NBDPS is a multi-site population-based case-control study. The present analysis included 3,346 case infants and 6,642 control infants born from October 1997 through December 2005. Maternal telephone interview reports of demographic characteristics and conditions and exposures before and during pregnancy were collected. Odds ratios and 95% confidence intervals, adjusted for relevant covariates, were calculated to estimate the associations between maternal dietary caffeine intake (coffee, tea, soda, and chocolate) and maternal use of caffeine-containing medications and each defect. We observed small, statistically significant elevations in adjusted odds ratios ranging from 1.3 to 1.8 for total maternal dietary caffeine intake or specific types of caffeinated beverages and anotia/microtia, esophageal atresia, small intestinal atresia, and craniosynostosis; however, dose-response patterns were absent. Periconceptional use of caffeine-containing medications was infrequent and estimates were imprecise. We did not find convincing evidence of an association between maternal caffeine intake and the birth defects included in this study. The increasing popularity of caffeine-containing energy drinks and other caffeinated products may result in higher caffeine intake among women of childbearing age. Future studies should consider more detailed evaluation of such products. Copyright © 2010 Wiley-Liss, Inc.

  9. Laterality Defects in the National Birth Defects Prevention Study (1998–2007): Birth Prevalence and Descriptive Epidemiology

    PubMed Central

    Lin, Angela E.; Krikov, Sergey; Riehle-Colarusso, Tiffany; Frías, Jaime L.; Belmont, John; Anderka, Marlene; Geva, Tal; Getz, Kelly D.; Botto, Lorenzo D.

    2015-01-01

    Little is known epidemiologically about laterality defects. Using data from the National Birth Defects Prevention Study (NBDPS), a large multi-site case-control study of birth defects, we analyzed prevalence and selected characteristics in children born with laterality defects born from 1998 to 2007. We identified 517 nonsyndromic cases (378 heterotaxy, 73.1%; 139 situs inversus totalis [SIT], 26.9%) resulting in an estimated birth prevalence of 1.1 per 10,000 live births (95% confidence interval 1.0–1.2). Prevalence did not differ significantly across sites, over time, or by inclusion of pregnancy termination. Laterality defects were more common among preterm cases compared to term cases, and in children born to mothers who were non-white or younger than 20 years compared to white mothers or those age 25–29 years. The distribution of associated cardiac and extracardiac defects, excluding the expected heterotaxy anomalies, varied by type of laterality defect. Cases with heterotaxy were significantly more likely than those with SIT to have double outlet right ventricle, atrioventricular canal defects, pulmonary stenosis, non-tetralogy of Fallot pulmonary atresia with ventricular septal defect, totally and partially anomalous pulmonary venous return; also more likely to have orofacial clefts, esophageal atresia, bowel atresias, and omphalocele, though not reaching statistical significance. Relatively more common among cases with SIT were Dandy-Walker malformation, anotia/microtia, and limb deficiency. The similarity in the demographic characteristics of heterotaxy and SIT supports the hypothesis that they are part of a continuum of abnormal left-right axis patterning. These findings on laterality defects may help guide clinical care, future research, and prevention strategies. PMID:25099286

  10. Guidance for Preventing Birth Defects

    MedlinePlus

    ... Prevention. Commit to Healthy Choices to Help Prevent Birth Defects Language: English (US) Español (Spanish) Recommend on ... Tweet Share Compartir We know that not all birth defects can be prevented. But, we also know ...

  11. Next steps for birth defects research and prevention: The birth defects study to evaluate pregnancy exposures (BD-STEPS).

    PubMed

    Tinker, Sarah C; Carmichael, Suzan L; Anderka, Marlene; Browne, Marilyn L; Caspers Conway, Kristin M; Meyer, Robert E; Nembhard, Wendy N; Olney, Richard S; Reefhuis, Jennita

    2015-08-01

    The Birth Defects Study To Evaluate Pregnancy exposureS (BD-STEPS) is a population-based, multi-Center case-control study of modifiable risk factors for selected birth defects in the United States. BD-STEPS is the second major research effort of the Centers for Birth Defects Research and Prevention, which extends and expands the initial research effort, the National Birth Defects Prevention Study (NBDPS). BD-STEPS focuses on 17 categories of structural birth defects selected based on severity, prevalence, consistent ascertainment, and previous findings that warrant additional research. Cases are identified through existing birth defects surveillance programs; controls are from vital records or birth hospital logs from the same catchment area. BD-STEPS uses a standardized computer-assisted telephone interview to collect information from case and control mothers on topics including demographics, health conditions, and medication use. Following the maternal interview, selected Centers request permission to sample residual newborn screening blood spots from state repositories for genetic analyses. New components planned for BD-STEPS include linkages with external datasets and use of online questionnaires to collect in-depth information on selected exposures. BD-STEPS extends NBDPS by continuing to collect data on many exposures that were assessed in NBDPS, allowing data from both studies to be combined and providing an unprecedented sample size to analyze rare exposures. BD-STEPS expands upon NBDPS by collecting more detailed information on existing exposures as well as new exposures. The goal of BD-STEPS is to provide women and healthcare providers with information they need to make decisions to promote the healthiest pregnancy possible. © 2015 Wiley Periodicals, Inc.

  12. Maternal Exposure to Criteria Air Pollutants and Congenital Heart Defects in Offspring: Results from the National Birth Defects Prevention Study

    PubMed Central

    Luben, Thomas J.; Daniels, Julie L.; Fuentes, Montserrat; Richardson, David B.; Aylsworth, Arthur S.; Herring, Amy H.; Anderka, Marlene; Botto, Lorenzo; Correa, Adolfo; Gilboa, Suzanne M.; Langlois, Peter H.; Mosley, Bridget; Shaw, Gary M.; Siffel, Csaba; Olshan, Andrew F.

    2014-01-01

    Background: Epidemiologic literature suggests that exposure to air pollutants is associated with fetal development. Objectives: We investigated maternal exposures to air pollutants during weeks 2–8 of pregnancy and their associations with congenital heart defects. Methods: Mothers from the National Birth Defects Prevention Study, a nine-state case–control study, were assigned 1-week and 7-week averages of daily maximum concentrations of carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide and 24-hr measurements of fine and coarse particulate matter using the closest air monitor within 50 km to their residence during early pregnancy. Depending on the pollutant, a maximum of 4,632 live-birth controls and 3,328 live-birth, fetal-death, or electively terminated cases had exposure data. Hierarchical regression models, adjusted for maternal demographics and tobacco and alcohol use, were constructed. Principal component analysis was used to assess these relationships in a multipollutant context. Results: Positive associations were observed between exposure to nitrogen dioxide and coarctation of the aorta and pulmonary valve stenosis. Exposure to fine particulate matter was positively associated with hypoplastic left heart syndrome but inversely associated with atrial septal defects. Examining individual exposure-weeks suggested associations between pollutants and defects that were not observed using the 7-week average. Associations between left ventricular outflow tract obstructions and nitrogen dioxide and between hypoplastic left heart syndrome and particulate matter were supported by findings from the multipollutant analyses, although estimates were attenuated at the highest exposure levels. Conclusions: Using daily maximum pollutant levels and exploring individual exposure-weeks revealed some positive associations between certain pollutants and defects and suggested potential windows of susceptibility during pregnancy. Citation: Stingone JA, Luben TJ

  13. Maternal occupation and the risk of birth defects: an overview from the National Birth Defects Prevention Study.

    PubMed

    Herdt-Losavio, M L; Lin, S; Chapman, B R; Hooiveld, M; Olshan, A; Liu, X; DePersis, R D; Zhu, J; Druschel, C M

    2010-01-01

    To examine the association between a spectrum of 24 maternal occupations and 45 birth defects for hypothesis generating purposes. Cases of isolated and multiple birth defects (n = 8977) and all non-malformed live-born control births (n = 3833) included in the National Birth Defects Prevention Study (NBDPS) with estimated dates of delivery from 1 October 1997 through 31 December 2003 were included. A computer-assisted telephone interview with mothers was conducted. Occupational coding using the 2000 Standard Occupational Classification System and the 1997 North American Industry Classification System was completed for all jobs held by mothers. Jobs held from 1 month before pregnancy to the end of the third pregnancy month were considered exposures. Logistic regression models were run, adjusted for potential confounders. We also used a Bayesian approach to logistic regression. Approximately 72% of case mothers and 72% of control mothers in the NBDPS were employed. Several occupational groups were positively associated with one or more birth defects, including janitors/cleaners, scientists and electronic equipment operators. Using standard logistic regression, we found 42 (26 for Bayesian) significantly elevated risks of birth defects in offspring of working mothers. In addition, several other occupational groups were found to be negatively associated with one or more birth defects, including teachers and healthcare workers. Using standard logistic regression, we found 12 (11 for Bayesian) significantly reduced risks of birth defects among offspring of working women. Results from these analyses can be used for hypothesis generating purposes and guiding future investigations of occupational exposures and birth defects.

  14. The Association Between Reported Venlafaxine Use in Early Pregnancy and Birth Defects, National Birth Defects Prevention Study, 1997–2007

    PubMed Central

    Polen, Kara ND; Rasmussen, Sonja A; Riehle-Colarusso, Tiffany; Reefhuis, Jennita

    2015-01-01

    Background Few epidemiologic studies have investigated the use of venlafaxine (Effexor®), an antidepressant used to treat major depression and anxiety disorders in adults, during pregnancy. Our objective was to determine whether use of venlafaxine during pregnancy is associated with specific birth defects. Methods We used data from the National Birth Defects Prevention Study (NBDPS), a population-based, case-control study in the United States. Our analysis included mothers with pregnancies affected by one of 30 selected birth defects (cases) and babies without birth defects (controls) with estimated dates of delivery between 1997–2007. Exposure was any reported use of venlafaxine from one month preconception through the third month of pregnancy. We calculated adjusted odds ratios (aORs) and 95% Fisher’s Exact confidence intervals (CIs) for 24 birth defect groups for which at least 400 case mothers were interviewed. Our adjusted analyses controlled for maternal age and race-ethnicity. Results Among the 27,045 NBDPS participants who met inclusion criteria, 0.17% (14/8,002) of control mothers and 0.40% (77/19,043) of case mothers reported any use of venlafaxine from one month preconception through the third month of pregnancy. Statistically significant associations were found for anencephaly, atrial septal defect (ASD) secundum or ASD not otherwise specified, coarctation of the aorta, cleft palate, and gastroschisis. Conclusions Our data suggest associations between periconceptional use of venlafaxine and some birth defects. However, sample sizes were small, confidence intervals were wide, and additional studies are needed to confirm these results. PMID:23281074

  15. Association between reported venlafaxine use in early pregnancy and birth defects, national birth defects prevention study, 1997-2007.

    PubMed

    Polen, Kara N D; Rasmussen, Sonja A; Riehle-Colarusso, Tiffany; Reefhuis, Jennita

    2013-01-01

    Few epidemiologic studies have investigated the use of venlafaxine (Effexor XR capsules, Product Monograph, Wyeth, Montreal, Canada), an antidepressant used to treat major depression and anxiety disorders in adults, during pregnancy. Our objective was to determine whether use of venlafaxine during pregnancy is associated with specific birth defects. We used data from the National Birth Defects Prevention Study (NBDPS), a population-based, case-control study in the United States. Our analysis included mothers with pregnancies affected by one of 30 selected birth defects (cases) and babies without birth defects (controls) with estimated dates of delivery between 1997 and 2007. Exposure was any reported use of venlafaxine from 1 month preconception through the third month of pregnancy. We calculated adjusted odds ratios (aORs) and 95% Fisher Exact confidence intervals (CIs) for 24 birth defect groups for which at least 400 case mothers were interviewed. Our adjusted analyses controlled for maternal age and race/ethnicity. Among the 27,045 NBDPS participants who met inclusion criteria, 0.17% (14/8002) of control mothers and 0.40% (77/19,043) of case mothers reported any use of venlafaxine from 1 month preconception through the third month of pregnancy. Statistically significant associations were found for anencephaly, atrial septal defect (ASD) secundum, or ASD not otherwise specified, coarctation of the aorta, cleft palate, and gastroschisis. Our data suggest associations between periconceptional use of venlafaxine and some birth defects. However, sample sizes were small, CIs were wide, and additional studies are needed to confirm these results. Copyright © 2012 Wiley Periodicals, Inc.

  16. Association between maternal occupational exposure to organic solvents and congenital heart defects, National Birth Defects Prevention Study, 1997–2002

    PubMed Central

    Gilboa, SM; Desrosiers, TA; Lawson, CC; Lupo, PJ; Riehle-Colarusso, T; Stewart, PA; van Wijngaarden, E; Waters, MA; Correa, A

    2015-01-01

    Objective To examine the relation between congenital heart defects (CHDs) in offspring and estimated maternal occupational exposure to chlorinated solvents, aromatic solvents, and Stoddard solvent during the period from one month before conception through the first trimester. Methods The study population included mothers of infants with simple, isolated CHDs and mothers of control infants who delivered from 1997 through 2002 and participated in the National Birth Defects Prevention Study. Two methods to assess occupational solvent exposure were employed: an expert consensus-based approach and a literature-based approach. Multiple logistic regression was used to calculate adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between solvent classes and CHDs. Results 2,951 control mothers and 2,047 CHD case mothers were included. Using the consensus-based approach, associations were observed for exposure to any solvent and any chlorinated solvent with perimembranous ventricular septal defects (OR 1.6; 95% CI 1.0 to 2.6 and OR 1.7; 95% CI 1.0 to 2.8 respectively). Using the literature-based approach, associations were observed for: any solvent exposure with aortic stenosis (OR 2.1; 95% CI 1.1 to 4.1); and Stoddard solvent exposure with d-transposition of the great arteries (OR 2.0; 95% CI 1.0 to 4.2), right ventricular outflow tract obstruction defects (OR 1.9; 95% CI 1.1 to 3.3), and pulmonary valve stenosis (OR 2.1; 95% CI 1.1 to 3.8). Conclusions We found evidence of associations between occupational exposure to solvents and several types of CHDs. These results should be interpreted in light of the potential for misclassification of exposure. PMID:22811060

  17. Maternal Occupational Pesticide Exposure and Risk of Congenital Heart Defects in the National Birth Defects Prevention Study

    PubMed Central

    Rocheleau, Carissa M.; Bertke, Stephen J.; Lawson, Christina C.; Romitti, Paul A.; Sanderson, Wayne T.; Malik, Sadia; Lupo, Philip J.; Desrosiers, Tania A.; Bell, Erin; Druschel, Charlotte; Correa, Adolfo; Reefhuis, Jennita

    2015-01-01

    BACKGROUND Congenital heart defects (CHDs) are common birth defects, affecting approximately 1% of live births. Pesticide exposure has been suggested as an etiologic factor for CHDs, but previous results were inconsistent. METHODS We examined maternal occupational exposure to fungicides, insecticides, and herbicides for 3328 infants with CHDs and 2988 unaffected control infants of employed mothers using data for 1997 through 2002 births from the National Birth Defects Prevention Study, a population-based multisite case-control study. Potential pesticide exposure from 1 month before conception through the first trimester of pregnancy was assigned by an expert-guided task-exposure matrix and job history details self-reported by mothers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression. RESULTS Maternal occupational exposure to pesticides was not associated with CHDs overall. In examining specific CHD subtypes compared with controls, some novel associations were observed with higher estimated pesticide exposure: insecticides only and secundum atrial septal defect (OR =1.8; 95% CI, 1.3–2.7, 40 exposed cases); both insecticides and herbicides and hypoplastic left heart syndrome (OR =5.1; 95% CI, 1.7–15.3, 4 exposed cases), as well as pulmonary valve stenosis (OR =3.6; 95% CI, 1.3–10.1, 5 exposed cases); and insecticides, herbicides, and fungicides and tetralogy of Fallot (TOF) (OR =2.2; 95% CI, 1.2–4.0, 13 exposed cases). CONCLUSION Broad pesticide exposure categories were not associated with CHDs overall, but examining specific CHD subtypes revealed some increased odds ratios. These results highlight the importance of examining specific CHDs separately. Because of multiple comparisons, additional work is needed to verify these associations. PMID:26033688

  18. Are epidemiological approaches suitable to study risk/preventive factors for human birth defects?

    PubMed Central

    Oberg, Anna Sara

    2015-01-01

    Birth defects are a major cause of infant morbidity and mortality and contribute substantially to long-term disability. One out of every 33 babies is born with some type of birth defect. Despite decades of research on environmental, behavioral and genetic risk factors, the vast majority of birth defects still occur without known cause. It is possible that birth defects are largely stochastic (and unavoidable) events, at which efforts to investigate their causes would be futile and unjustified. In this commentary we argue for the continued research into risk/preventive factors of human birth defects, and outline why epidemiological studies are suitable for such endeavors. First we discuss what factors to target (genetic or environmental) and how to define the pertinent research questions. Then we present a short review of both epidemiological contributions in the past and approaches to advance the field in the future. After considering also their limitations, we conclude that modern epidemiologic approaches are invaluable to advance our understanding of risk factors for human birth defects, and that interdisciplinary collaborations will also be essential to further our knowledge. PMID:25722958

  19. Maternal Antihypertensive Medication Use and Congenital Heart Defects: Updated Results From the National Birth Defects Prevention Study.

    PubMed

    Fisher, Sarah C; Van Zutphen, Alissa R; Werler, Martha M; Lin, Angela E; Romitti, Paul A; Druschel, Charlotte M; Browne, Marilyn L

    2017-05-01

    Previous NBDPS (National Birth Defects Prevention Study) findings from 1997 to 2003 suggested that maternal antihypertensive use was associated with congenital heart defects (CHDs). We re-examined associations between specific antihypertensive medication classes and specific CHDs with additional NBDPS data from 2004 to 2011. After excluding mothers missing hypertension information or who reported pregestational diabetes mellitus, a multiple birth, or antihypertensive use but no hypertension, we compared self-reported maternal exposure data on 10 625 CHD cases and 11 137 nonmalformed controls. We calculated adjusted odds ratios [95% confidence intervals] to estimate the risk of specific CHDs associated with antihypertensive use during the month before conception through the third month of pregnancy, controlling for maternal age, race/ethnicity, body mass index, first trimester cigarette smoking, and NBDPS site. Overall, 164 (1.5%) case mothers and 102 (0.9%) control mothers reported early pregnancy antihypertensive use for their hypertension. We observed increased risk of 4 CHD phenotypes, regardless of antihypertensive medication class reported: coarctation of the aorta (2.50 [1.52-4.11]), pulmonary valve stenosis (2.19 [1.44-3.34]), perimembranous ventricular septal defect (1.90 [1.09-3.31]), and secundum atrial septal defect (1.94 [1.36-2.79]). The associations for these phenotypes were statistically significant for mothers who reported β-blocker use or renin-angiotensin system blocker use; estimates for other antihypertensive medication classes were generally based on fewer exposed cases and were less stable but remained elevated. Our results support and expand on earlier NBDPS findings that antihypertensive medication use may be associated with increased risk of specific CHDs, although we cannot completely rule out confounding by underlying disease characteristics. © 2017 American Heart Association, Inc.

  20. Maternal exposures in the National Birth Defects Prevention Study: Time trends of selected exposures.

    PubMed

    Dawson, April L; Razzaghi, Hilda; Arth, Annelise; Canfield, Mark A; Parker, Samantha E; Reefhuis, Jennita

    2015-08-01

    Our objective was to describe time trends in selected pregnancy exposures in the National Birth Defects Prevention Study (NBDPS). We analyzed data from the NBDPS, a multi-site case-control study of major birth defects, for mothers of live-born infants without birth defects (controls), with an expected date of delivery (EDD) from 1998 to 2011. Mothers from the 10 participating centers across the United States were interviewed by phone between 6 weeks and 2 years after the EDD. We focused on maternal race/ethnicity and five maternal risk factors: obesity, use of folic acid-containing multivitamins, opioid analgesics, selective serotonin reuptake inhibitors, and loratadine because of their prevalence of use and some reports of associations with major birth defects. Prevalence time trends were examined using the Kendall's τβ test statistic. The exposure trend analysis included 11,724 control mothers with EDDs from 1998 to 2011. We observed a significant increase in obesity prevalence among control mothers, as well as use of selective serotonin reuptake inhibitors and loratadine. We also observed an increase in periconceptional use of folic acid-containing multivitamins. Some of the time trends varied by race/ethnicity. No remarkable trend in the overall use of opioid analgesics was observed. The racial/ethnic distribution of mothers changed slightly during the study period. Long-term, population-based case-control studies continue to be an effective way to assess exposure-birth defects associations and provide guidance to health care providers. However, investigators examining rare outcomes covering many years of data collection need to be cognizant of time trends in exposures. © 2015 Wiley Periodicals, Inc.

  1. Maternal exposures in the National Birth Defects Prevention Study: time trends of selected exposures

    PubMed Central

    Dawson, April L.; Razzaghi, Hilda; Arth, Annelise; Canfield, Mark A.; Parker, Samantha E.; Reefhuis, Jennita

    2015-01-01

    Background Our objective was to describe time trends in selected pregnancy exposures in the National Birth Defects Prevention Study (NBDPS). Methods We analyzed data from the NBDPS, a multi-site case-control study of major birth defects, for mothers of live-born infants without birth defects (controls), with an expected date of delivery (EDD) from 1998 –2011. Mothers from the 10 participating centers across the United States were interviewed by phone between six weeks and two years after the EDD. We focused on maternal race/ethnicity and five maternal risk factors: obesity, use of folic acid-containing multivitamins, opioid analgesics, selective serotonin reuptake inhibitors (SSRIs), and loratadine because of their prevalence of use and some reports of associations with major birth defects. Prevalence time trends were examined using the Kendall’s τβ test statistic. Results The exposure trend analysis included 11,724 control mothers with EDDs from 1998–2011. We observed a significant increase in obesity prevalence among control mothers, as well as use of SSRIs and loratadine. We also observed an increase in periconceptional use of folic acid-containing multivitamins. Some of the time trends varied by race/ethnicity. No remarkable trend in the overall use of opioid analgesics was observed. The racial/ethnic distribution of mothers changed slightly during the study period. Conclusions Long-term, population-based case-control studies continue to be an effective way to assess exposure-birth defects associations and provide guidance to health care providers. However, investigators examining rare outcomes covering many years of data collection need to be cognizant of time trends in exposures. PMID:25884728

  2. Diabetes and obesity-related genes and the risk of neural tube defects in the national birth defects prevention study.

    PubMed

    Lupo, Philip J; Canfield, Mark A; Chapa, Claudia; Lu, Wei; Agopian, A J; Mitchell, Laura E; Shaw, Gary M; Waller, D Kim; Olshan, Andrew F; Finnell, Richard H; Zhu, Huiping

    2012-12-15

    Few studies have evaluated genetic susceptibility related to diabetes and obesity as a risk factor for neural tube defects (NTDs). The authors investigated 23 single nucleotide polymorphisms among 9 genes (ADRB3, ENPP1, FTO, LEP, PPARG, PPARGC1A, SLC2A2, TCF7L2, and UCP2) associated with type 2 diabetes or obesity. Samples were obtained from 737 NTD case-parent triads included in the National Birth Defects Prevention Study during 1999-2007. Log-linear models were used to evaluate maternal and offspring genetic effects. After application of the false discovery rate, there were 5 significant maternal genetic effects. The less common alleles at the 4 FTO single nucleotide polymorphisms showed a reduction of NTD risk (for rs1421085, relative risk (RR) = 0.73 (95% confidence interval (CI): 0.62, 0.87); for rs8050136, RR = 0.79 (95% CI: 0.67, 0.93); for rs9939609, RR = 0.79 (95% CI: 0.67, 0.94); and for rs17187449, RR = 0.80 (95% CI: 0.68, 0.95)). Additionally, maternal LEP rs2071045 (RR = 1.31, 95% CI: 1.08, 1.60) and offspring UCP2 rs660339 (RR = 1.32, 95% CI: 1.06, 1.64) were associated with NTD risk. Furthermore, the maternal genotype for TCF7L2 rs3814573 suggested an increased NTD risk among obese women. These findings indicate that maternal genetic variants associated with glucose homeostasis may modify the risk of having an NTD-affected pregnancy.

  3. The National Birth Defects Prevention Study: A review of the methods.

    PubMed

    Reefhuis, Jennita; Gilboa, Suzanne M; Anderka, Marlene; Browne, Marilyn L; Feldkamp, Marcia L; Hobbs, Charlotte A; Jenkins, Mary M; Langlois, Peter H; Newsome, Kimberly B; Olshan, Andrew F; Romitti, Paul A; Shapira, Stuart K; Shaw, Gary M; Tinker, Sarah C; Honein, Margaret A

    2015-08-01

    The National Birth Defects Prevention Study (NBDPS) is a large population-based multicenter case-control study of major birth defects in the United States. Data collection took place from 1998 through 2013 on pregnancies ending between October 1997 and December 2011. Cases could be live born, stillborn, or induced terminations, and were identified from birth defects surveillance programs in Arkansas, California, Georgia, Iowa, Massachusetts, New Jersey, New York, North Carolina, Texas, and Utah. Controls were live born infants without major birth defects identified from the same geographical regions and time periods as cases by means of either vital records or birth hospitals. Computer-assisted telephone interviews were completed with women between 6 weeks and 24 months after the estimated date of delivery. After completion of interviews, families received buccal cell collection kits for the mother, father, and infant (if living). There were 47,832 eligible cases and 18,272 eligible controls. Among these, 32,187 (67%) and 11,814 (65%), respectively, provided interview information about their pregnancies. Buccal cell collection kits with a cytobrush for at least one family member were returned by 19,065 case and 6,211 control families (65% and 59% of those who were sent a kit). More than 500 projects have been proposed by the collaborators and over 200 manuscripts published using data from the NBDPS through December 2014. The NBDPS has made substantial contributions to the field of birth defects epidemiology through its rigorous design, including case classification, detailed questionnaire and specimen collection, large study population, and collaborative activities across Centers. © 2015 Wiley Periodicals, Inc.

  4. The National Birth Defects Prevention Study: a review of the methods

    PubMed Central

    Reefhuis, Jennita; Gilboa, Suzanne M.; Anderka, Marlene; Browne, Marilyn L.; Feldkamp, Marcia L.; Hobbs, Charlotte A.; Jenkins, Mary M.; Langlois, Peter H.; Newsome, Kimberly B.; Olshan, Andrew F.; Romitti, Paul A.; Shapira, Stuart K.; Shaw, Gary M.; Tinker, Sarah C.; Honein, Margaret A.

    2015-01-01

    Background The National Birth Defects Prevention Study (NBDPS) is a large population-based multi-center case-control study of major birth defects in the United States. Methods Data collection took place from 1998 through 2013 on pregnancies ending between October 1997 and December 2011. Cases could be live born, stillborn or induced terminations, and were identified from birth defects surveillance programs in Arkansas, California, Georgia, Iowa, Massachusetts, New Jersey, New York, North Carolina, Texas and Utah. Controls were live born infants without major birth defects identified from the same geographical regions and time periods as cases via either vital records or birth hospitals. Computer-assisted telephone interviews were completed with women between 6 weeks and 24 months after the estimated date of delivery. After completion of interviews, families received buccal cell collection kits for the mother, father and infant (if living). Results There were 47,832 eligible cases and 18,272 eligible controls. Among these, 32,187 (67%) and 11,814 (65%) respectively, provided interview information about their pregnancies. Buccal cell collection kits with a cytobrush for at least one family member were returned by 19,065 case and 6,211 control families (65% and 59% of those who were sent a kit). More than 500 projects have been proposed by the collaborators and over 200 manuscripts published using data from the NBDPS through December 2014. Conclusion The NBDPS has made substantial contributions to the field of birth defects epidemiology through its rigorous design, including case classification, detailed questionnaire and specimen collection, large study population, and collaborative activities across Centers. PMID:26033852

  5. Risk factors for isolated biliary atresia, National Birth Defects Prevention Study, 1997-2002.

    PubMed

    The, Natalie S; Honein, Margaret A; Caton, Alissa R; Moore, Cynthia A; Siega-Riz, Anna Maria; Druschel, Charlotte M

    2007-10-01

    Biliary atresia is a rare birth defect that affects 1 in 12,000 to 1 in 19,500 live births. We used data from the National Birth Defects Prevention Study, a multistate case-control study, to identify potential risk factors for isolated biliary atresia (no additional unrelated major birth defects diagnosed). Infants were identified from eight states from 1997 to 2002, with clinical information abstracted from medical records. Potential risk factors assessed include: demographic factors, seasonality, preterm birth, maternal smoking, maternal alcohol use, maternal illicit drug use, maternal health, maternal medication use, maternal vitamin use, and maternal nutrition. Infants of non-Hispanic black mothers were more likely to have biliary atresia than infants of non-Hispanic white mothers (adjusted odds ratio (aOR) = 2.29, 95% confidence interval (CI) 1.07-4.93) and infants conceived during the spring season were more likely to have biliary atresia than infants conceived in winter (aOR = 2.33, 95%CI 1.05-5.16). Low intakes of vitamin E, copper, phosphorus, and beta tocopherol were associated with the occurrence of isolated biliary atresia (borderline significance). Low iron intake had a borderline inverse association with biliary atresia. While this analysis provides support for previous reports of a possible association between seasonal variation and the occurrence of biliary atresia, more data are needed to evaluate whether the seasonal variation is related to infectious agents. The role of nutrients in the development of biliary atresia remains unclear. Further studies of genetic, infectious, and nutrient exposures and the association of biliary atresia are warranted. 2007 Wiley-Liss, Inc

  6. Impact of Time to Maternal Interview on Interview Responses in the National Birth Defects Prevention Study

    PubMed Central

    Tinker, Sarah C.; Gibbs, Cassandra; Strickland, Matthew J.; Devine, Owen J.; Crider, Krista S.; Werler, Martha M.; Anderka, Marlene T.; Reefhuis, Jennita

    2013-01-01

    Prenatal exposures often are assessed using retrospective interviews. Time from exposure to interview may influence data accuracy. We investigated the association of time to interview (TTI) with aspects of interview responses in the National Birth Defects Prevention Study, a population-based case-control study of birth defects in 10 US states. Mothers completed a computer-assisted telephone interview 1.5–24 months after their estimated date of delivery. Proxy metrics for interview quality were whether certain exposures were reported, whether the start month of reported medication use or illness was reported, or whether responses were missing. Interaction by case status was assessed. Interviews were completed with 30,542 mothers (22,366 cases and 8,176 controls) who gave birth between 1997 and 2007. Mothers of cases were interviewed later than were mothers of controls (11.7 months vs. 9.5 months, respectively). In adjusted analyses, having a TTI that was greater than 6 months was associated with only a few aspects of interview responses (e.g., start month of pseudoephedrine use). Interaction by case-control status was observed for some exposures; mothers of controls had a greater reduction in interview quality with increased TTI in these instances (e.g., report of morning sickness, start month of acetaminophen use and ibuprofen use). The results suggest that TTI might impact interview responses; however, the impact may be minimal and specific to the type of exposure. PMID:23645625

  7. Association between antibiotic use among pregnant women with urinary tract infections in the first trimester and birth defects, National Birth Defects Prevention Study 1997 to 2011.

    PubMed

    Ailes, Elizabeth C; Gilboa, Suzanne M; Gill, Simerpal K; Broussard, Cheryl S; Crider, Krista S; Berry, Robert J; Carter, Tonia C; Hobbs, Charlotte A; Interrante, Julia D; Reefhuis, Jennita

    2016-11-01

    Previous studies noted associations between birth defects and some antibiotics (e.g., nitrofurantoin, sulfonamides) but not others (e.g., penicillins). It is unclear if previous findings were due to antibiotic use, infections, or chance. To control for potential confounding by indication, we examined associations between antibiotic use and birth defects, among women reporting urinary tract infections (UTIs). The National Birth Defects Prevention Study is a multi-site, population-based case-control study. Case infants/fetuses have any of over 30 major birth defects and controls are live-born infants without major birth defects. We analyzed pregnancies from 1997 to 2011 to estimate the association between maternally reported periconceptional (month before conception through the third month of pregnancy) use of nitrofurantoin, trimethoprim-sulfamethoxazole, or cephalosporins and specific birth defects, among women with periconceptional UTIs. Women with periconceptional UTIs who reported penicillin use served as the comparator. Periconceptional UTIs were reported by 7.8% (2029/26,068) of case and 6.7% (686/10,198) of control mothers. Most (68.2% of case, 66.6% of control mothers) also reported antibiotic use. Among 608 case and 231 control mothers reporting at least one periconceptional UTI and certain antibiotic use, compared with penicillin, nitrofurantoin use was associated with oral clefts in the offspring (adjusted odds ratio, 1.97 [95% confidence interval, 1.10-3.53]), trimethoprim-sulfamethoxazole use with esophageal atresia (5.31 [1.39-20.24]) and diaphragmatic hernia (5.09 [1.20-21.69]), and cephalosporin use with anorectal atresia/stenosis (5.01 [1.34-18.76]). Periconceptional exposure to some antibiotics might increase the risk for certain birth defects. However, because individual birth defects are rare, absolute risks should drive treatment decisions.Birth Defects Research (Part A) 106:940-949, 2016.© 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals

  8. Prenatal Nitrate Intake from Drinking Water and Selected Birth Defects in Offspring of Participants in the National Birth Defects Prevention Study

    PubMed Central

    Weyer, Peter J.; Romitti, Paul A.; Mohanty, Binayak P.; Shinde, Mayura U.; Vuong, Ann M.; Sharkey, Joseph R.; Dwivedi, Dipankar; Horel, Scott A.; Kantamneni, Jiji; Huber, John C.; Zheng, Qi; Werler, Martha M.; Kelley, Katherine E.; Griesenbeck, John S.; Zhan, F. Benjamin; Langlois, Peter H.; Suarez, Lucina; Canfield, Mark A.

    2013-01-01

    Background: Previous studies of prenatal exposure to drinking-water nitrate and birth defects in offspring have not accounted for water consumption patterns or potential interaction with nitrosatable drugs. Objectives: We examined the relation between prenatal exposure to drinking-water nitrate and selected birth defects, accounting for maternal water consumption patterns and nitrosatable drug exposure. Methods: With data from the National Birth Defects Prevention Study, we linked addresses of 3,300 case mothers and 1,121 control mothers from the Iowa and Texas sites to public water supplies and respective nitrate measurements. We assigned nitrate levels for bottled water from collection of representative samples and standard laboratory testing. Daily nitrate consumption was estimated from self-reported water consumption at home and work. Results: With the lowest tertile of nitrate intake around conception as the referent group, mothers of babies with spina bifida were 2.0 times more likely (95% CI: 1.3, 3.2) to ingest ≥ 5 mg nitrate daily from drinking water (vs. < 0.91 mg) than control mothers. During 1 month preconception through the first trimester, mothers of limb deficiency, cleft palate, and cleft lip cases were, respectively, 1.8 (95% CI: 1.1, 3.1), 1.9 (95% CI: 1.2, 3.1), and 1.8 (95% CI: 1.1, 3.1) times more likely than control mothers to ingest ≥ 5.42 mg of nitrate daily (vs. < 1.0 mg). Higher water nitrate intake did not increase associations between prenatal nitrosatable drug use and birth defects. Conclusions: Higher water nitrate intake was associated with several birth defects in offspring, but did not strengthen associations between nitrosatable drugs and birth defects. Citation: Brender JD, Weyer PJ, Romitti PA, Mohanty BP, Shinde MU, Vuong AM, Sharkey JR, Dwivedi D, Horel SA, Kantamneni J, Huber JC Jr., Zheng Q, Werler MM, Kelley KE, Griesenbeck JS, Zhan FB, Langlois PH, Suarez L, Canfield MA, and the National Birth Defects Prevention Study

  9. Next steps for birth defects research and prevention: The Birth Defects Study To Evaluate Pregnancy exposureS (BD-STEPS)

    PubMed Central

    Tinker, Sarah C.; Carmichael, Suzan L.; Anderka, Marlene; Browne, Marilyn L.; Caspers Conway, Kristin M.; Meyer, Robert E.; Nembhard, Wendy N.; Olney, Richard S.; Reefhuis, Jennita

    2015-01-01

    Background The Birth Defects Study To Evaluate Pregnancy exposureS (BD-STEPS) is a population-based, multi-Center case-control study of modifiable risk factors for selected birth defects in the United States. BD-STEPS is the second major research effort of the Centers for Birth Defects Research and Prevention, which extends and expands the initial research effort, the National Birth Defects Prevention Study (NBDPS). Methods BD-STEPS focuses on 17 categories of structural birth defects selected based on severity, prevalence, consistent ascertainment, and previous findings that warrant additional research. Cases are identified through existing birth defects surveillance programs; controls are from vital records or birth hospital logs from the same catchment area. BD-STEPS usess a standardized computer-assisted telephone interview to collect information from case and control mothers on topics including demographics, health conditions, and medication use. Following the maternal interview, selected Centers request permission to sample residual newborn screening blood spots from state repositories for genetic analyses. New components planned for BD-STEPS include linkages with external datasets and use of online questionnaires to collect in-depth information on selected exposures. Results BD-STEPS extends NBDPS by continuing to collect data on many exposures that were assessed in NBDPS, allowing data from both studies to be combined and providing an unprecedented sample size to analyze rare exposures. BD-STEPS expands upon NBDPS by collecting more detailed information on existing exposures as well as new exposures. Conclusions The goal of BD-STEPS is to provide women and healthcare providers with information they need to make decisions to promote the healthiest pregnancy possible. PMID:25846741

  10. Communicating (birth defects) prevention information to a hmong population in Wisconsin: a study of cultural relevance.

    PubMed

    Viste, Jane

    2007-01-01

    Compelling research from the early 1990s indicated a strong correlation between the consumption of the B-vitamin folic acid and the prevention of a serious birth defect (neural tube defect) in infants. This article examines numerous challenges the author faced when attempting to produce a culturally relevant folic acid brochure for Hmong women of childbearing age in LaCrosse, Wisconsin, part of a broad folic acid education program. An immediate challenge arose from the traditional Hmong belief that birth defects can be either a curse or a gift, "preassigned" in a former life and therefore not preventable. Other challenges that were addressed included language, acculturation and nutrition, literacy, attitudes toward Western health care practices, and attitudes toward taking medications, including a daily multivitamin. In order for public health communicators to reach increasingly diverse ethnic and cultural identities with important health messages, it is essential that project planning start from the target group's cultural context. It is hoped that the lessons learned through this project can be applied to other communications efforts with other cultural groups.

  11. Hypospadias and maternal exposure to atrazine via drinking water in the National Birth Defects Prevention study.

    PubMed

    Winston, Jennifer J; Emch, Michael; Meyer, Robert E; Langlois, Peter; Weyer, Peter; Mosley, Bridget; Olshan, Andrew F; Band, Lawrence E; Luben, Thomas J

    2016-07-15

    Hypospadias is a relatively common birth defect affecting the male urinary tract. It has been suggested that exposure to endocrine disrupting chemicals might increase the risk of hypospadias by interrupting normal urethral development. Using data from the National Birth Defects Prevention Study, a population-based case-control study, we considered the role of maternal exposure to atrazine, a widely used herbicide and potential endocrine disruptor, via drinking water in the etiology of 2nd and 3rd degree hypospadias. We used data on 343 hypospadias cases and 1,422 male controls in North Carolina, Arkansas, Iowa, and Texas from 1998-2005. Using catchment level stream and groundwater contaminant models from the US Geological Survey, we estimated atrazine concentrations in public water supplies and in private wells. We assigned case and control mothers to public water supplies based on geocoded maternal address during the critical window of exposure for hypospadias (i.e., gestational weeks 6-16). Using maternal questionnaire data about water consumption and drinking water, we estimated a surrogate for total maternal consumption of atrazine via drinking water. We then included additional maternal covariates, including age, race/ethnicity, parity, and plurality, in logistic regression analyses to consider an association between atrazine and hypospadias. When controlling for maternal characteristics, any association between hypospadias and daily maternal atrazine exposure during the critical window of genitourinary development was found to be weak or null (odds ratio for atrazine in drinking water = 1. 00, 95 % CI = 0.97 to 1.03 per 0.04 μg/day increase; odds ratio for maternal consumption = 1.02, 95 % CI = 0.99 to 1.05; per 0.05 μg/day increase). While the association that we observed was weak, our results suggest that additional research into a possible association between atrazine and hypospadias occurrence, using a more sensitive exposure metric

  12. Control selection and participation in an ongoing, population-based, case-control study of birth defects: the National Birth Defects Prevention Study.

    PubMed

    Cogswell, Mary E; Bitsko, Rebecca H; Anderka, Marlene; Caton, Alissa R; Feldkamp, Marcia L; Hockett Sherlock, Stacey M; Meyer, Robert E; Ramadhani, Tunu; Robbins, James M; Shaw, Gary M; Mathews, T J; Royle, Marjorie; Reefhuis, Jennita

    2009-10-15

    To evaluate the representativeness of controls in an ongoing, population-based, case-control study of birth defects in 10 centers across the United States, researchers compared 1997-2003 birth certificate data linked to selected controls (n = 6,681) and control participants (n = 4,395) with those from their base populations (n = 2,468,697). Researchers analyzed differences in population characteristics (e.g., percentage of births at > or =2,500 g) for each group. Compared with their base populations, control participants did not differ in distributions of maternal or paternal age, previous livebirths, maternal smoking, or diabetes, but they did differ in other maternal (i.e., race/ethnicity, education, entry into prenatal care) and infant (i.e., birth weight, gestational age, and plurality) characteristics. Differences in distributions of maternal, but not infant, characteristics were associated with participation by selected controls. Absolute differences in infant characteristics for the base population versus control participants were < or =1.3 percentage points. Differences in infant characteristics were greater at centers that selected controls from hospitals compared with centers that selected controls from electronic birth certificates. These findings suggest that control participants in the National Birth Defects Prevention Study generally are representative of their base populations. Hospital-based control selection may slightly underascertain infants affected by certain adverse birth outcomes.

  13. Prenatal nitrate intake from drinking water and selected birth defects in offspring of participants in the national birth defects prevention study.

    PubMed

    Brender, Jean D; Weyer, Peter J; Romitti, Paul A; Mohanty, Binayak P; Shinde, Mayura U; Vuong, Ann M; Sharkey, Joseph R; Dwivedi, Dipankar; Horel, Scott A; Kantamneni, Jiji; Huber, John C; Zheng, Qi; Werler, Martha M; Kelley, Katherine E; Griesenbeck, John S; Zhan, F Benjamin; Langlois, Peter H; Suarez, Lucina; Canfield, Mark A

    2013-09-01

    Previous studies of prenatal exposure to drinking-water nitrate and birth defects in offspring have not accounted for water consumption patterns or potential interaction with nitrosatable drugs. We examined the relation between prenatal exposure to drinking-water nitrate and selected birth defects, accounting for maternal water consumption patterns and nitrosatable drug exposure. With data from the National Birth Defects Prevention Study, we linked addresses of 3,300 case mothers and 1,121 control mothers from the Iowa and Texas sites to public water supplies and respective nitrate measurements. We assigned nitrate levels for bottled water from collection of representative samples and standard laboratory testing. Daily nitrate consumption was estimated from self-reported water consumption at home and work. With the lowest tertile of nitrate intake around conception as the referent group, mothers of babies with spina bifida were 2.0 times more likely (95% CI: 1.3, 3.2) to ingest ≥ 5 mg nitrate daily from drinking water (vs. < 0.91 mg) than control mothers. During 1 month preconception through the first trimester, mothers of limb deficiency, cleft palate, and cleft lip cases were, respectively, 1.8 (95% CI: 1.1, 3.1), 1.9 (95% CI: 1.2, 3.1), and 1.8 (95% CI: 1.1, 3.1) times more likely than control mothers to ingest ≥ 5.42 mg of nitrate daily (vs. < 1.0 mg). Higher water nitrate intake did not increase associations between prenatal nitrosatable drug use and birth defects. Higher water nitrate intake was associated with several birth defects in offspring, but did not strengthen associations between nitrosatable drugs and birth defects.

  14. Antiherpetic medication use and the risk of gastroschisis: Findings from the National Birth Defects Prevention Study, 1997-2007

    PubMed Central

    Ahrens, Katherine A.; Anderka, Marlene T.; Feldkamp, Marcia L.; Canfield, Mark A.; Mitchell, Allen A.; Werler, Martha M.

    2013-01-01

    Background Previous studies examining the teratogenic effects of antiherpetic medications have found no associations for birth defects overall but have not examined the risk of specific birth defects. Methods The National Birth Defects Prevention Study ascertains population-based cases with birth defects and live-born controls without birth defects in ten states across the United States for the purpose of identifying potential teratogenic risk factors. Mothers of cases and controls are interviewed within two years of their estimated date of delivery about demographic, medical and behavioral factors before and during pregnancy. This analysis examined the possible association between use of antiherpetic medications (acyclovir, valacyclovir or famciclovir) during early pregnancy and gastroschisis, a birth defect of the abdominal wall. Results The mothers of 1.1% (n=10) of 941 gastroschisis cases and 0.3% (n=27) of 8339 controls reported antiherpetic medication use during the month before conception through the third month of pregnancy. The adjusted odds ratios for such use in relation to gastroschisis were 4.68 (95% confidence interval [1.65, 13.28]) and 4.68 [1.15, 19.03] among women with and without self-reported genital herpes, respectively, when compared to women without antiherpetic use or herpes. Among women reporting no antiherpetic medication use, the odds ratio for self-reported genital herpes in relation to gastroschisis was 3.00 [1.58, 5.68]. Conclusions Our study raises the possibility of an increased risk of gastroschisis due to either antiherpetic medication use during early pregnancy or the underlying genital herpes infection for which it was indicated. PMID:23772935

  15. Association of Paternal Age and Risk for Major Congenital Anomalies from the National Birth Defects Prevention Study, 1997–2004

    PubMed Central

    Green, Ridgely Fisk; Devine, Owen; Crider, Krista S.; Olney, Richard S.; Archer, Natalie; Olshan, Andrew F.; Shapira, Stuart K.

    2009-01-01

    Purpose The objective of this study was to examine the associations between paternal age and birth defects of unknown etiologies while carefully controlling for maternal age. Methods Using 1997–2004 data from the National Birth Defects Prevention Study, we fit logistic regression models with paternal and maternal age as continuous variables while adjusting for demographic and other factors. Results Elevated odds ratios for each year increase in paternal age were found for cleft palate (odds ratio (OR) = 1.02, 95% confidence interval (CI): 1.00, 1.04), diaphragmatic hernia (OR = 1.04, 95% CI: 1.02, 1.06), right ventricular outflow tract obstruction (OR = 1.03, 95% CI: 1.01, 1.04), and pulmonary valve stenosis (OR = 1.02, 95% CI: 1.01, 1.04). At younger paternal ages, each year increase in paternal age correlated with increased odds of having offspring with encephalocele, cataract, esophageal atresia, anomalous pulmonary venous return, and coarctation of the aorta, but these increased odds were not observed at older paternal ages. The effect of paternal age was modified by maternal age for gastroschisis, omphalocele, spina bifida, all orofacial clefts, and septal heart defects. Conclusions Our findings suggest that paternal age may be a risk factor for some multifactorial birth defects. PMID:20056435

  16. Analysis of Selected Maternal Exposures and Non-Syndromic Atrioventricular Septal Defects in the National Birth Defects Prevention Study, 1997–2005

    PubMed Central

    Patel, Sonali S.; Burns, Trudy L.; Botto, Lorenzo D.; Riehle-Colarusso, Tiffany J.; Lin, Angela E.; Shaw, Gary M.; Romitti, Paul A.

    2015-01-01

    Although the descriptive epidemiology of atrioventricular septal defects (AVSDs), a group of serious congenital heart defects (CHDs), has been recently reported, non-genetic risk factors have not been consistently identified. Using data (1997–2005) from the National Birth Defects Prevention Study, an ongoing multisite population-based case–control study, the association between selected non-genetic factors and non-syndromic AVSDs was examined. Data on periconceptional exposures to such factors were collected by telephone interview from 187 mothers of AVSD case infants and 6,703 mothers of unaffected infants. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated from logistic regression models. Mothers who reported cigarette smoking during the periconceptional period were more likely to have infants with AVSDs compared with non-smokers, independent of maternal age, periconceptional alcohol consumption, infant gestational age, family history of CHDs, and study site (aOR 1.5, 95% CI 1.1–2.4). The association was strongest in mothers who smoked more than 25 cigarettes/day. In addition, mothers with periconceptional passive smoke exposure were more likely to have infants with AVSDs than unexposed mothers, independent of maternal age, active periconceptional smoking, infant gestational age, and family history of CHDs (aOR 1.4, 95% CI 1.0–2.0). No associations were observed between AVSDs and maternal history of a urinary tract infection or pelvic inflammatory disease, maternal use of a wide variety of medications, maternal occupational exposure, parental drug use, or maternal alcohol consumption. If the results of this preliminary study can be replicated, minimizing maternal active and passive smoke exposure may decrease the incidence of AVSDs. PMID:22903798

  17. Maternal occupation and the risk of major birth defects: A follow-up analysis from the National Birth Defects Prevention Study

    PubMed Central

    Lin, Shao; Herdt-Losavio, Michele L.; Chapman, Bonnie R.; Munsie, Jean-Pierre; Olshan, Andrew F.; Druschel, Charlotte M.

    2013-01-01

    This study further examined the association between selected maternal occupations and a variety of birth defects identified from prior analysis and explored the effect of work hours and number of jobs held and potential interaction between folic acid and occupation. Data from a population-based, multi-center case-control study was used. Analyses included 45 major defects and specific sub-occupations under five occupational groups: healthcare workers, cleaners, scientists, teachers and personal service workers. Both logistic regression and Bayesian models (to minimize type-1 errors) were used, adjusted for potential confounders. Effect modification by folic acid was also assessed. More than any other occupation, nine different defects were positively associated with maids or janitors [odds ratio (OR) range: 1.72-3.99]. Positive associations were also seen between the following maternal occupations and defects in their children (OR range: 1.35-3.48): chemists/conotruncal heart and neural tube defects (NTDs), engineers/conotruncal defects, preschool teachers/cataracts and cleft lip with/without cleft palate (CL/P), entertainers/athletes/gastroschisis, and nurses/hydrocephalus and left ventricular outflow tract heart defects. Non-preschool teachers had significantly lower odds of oral clefts and gastroschisis in their offspring (OR range: 0.53-0.76). There was a suggestion that maternal folic acid use modified the effects with occupations including lowering the risk of NTDs and CL/P. No consistent patterns were found between maternal work hours or multiple jobs by occupation and the risk of birth defects. Overall, mothers working as maids, janitors, biologists, chemists, engineers, nurses, entertainers, child care workers and preschool teachers had increased risks of several malformations and non-preschool teachers had a lower risk of some defects. Maternal folic acid use reduced the odds of NTDs and CL/P among those with certain occupations. This hypothesis

  18. Maternal Occupational Exposure to Polycyclic Aromatic Hydrocarbons and Craniosynostosis among Offspring in the National Birth Defects Prevention Study

    PubMed Central

    O’Brien, Jacqueline L.; Langlois, Peter H.; Lawson, Christina C.; Scheuerle, Angela; Rocheleau, Carissa M.; Waters, Martha A.; Symanski, Elaine; Romitti, Paul A.; Agopian, A.J.; Lupo, Philip J.

    2015-01-01

    Background Evidence in animal models and humans suggests that exposure to polycyclic aromatic hydrocarbons (PAHs) may lead to birth defects. To our knowledge, this relationship has not been evaluated for craniosynostosis, a birth defect characterized by the premature closure of sutures in the skull. We conducted a case-control study to examine associations between maternal occupational exposure to PAHs and craniosynostosis. Methods We used data from craniosynostosis cases and control infants in the National Birth Defects Prevention Study (NBDPS) with estimated delivery dates from 1997–2002. Industrial hygienists reviewed occupational data from the computer-assisted telephone interview and assigned a yes/no rating of probable occupational PAH exposure for each job from one month before conception through delivery. We used logistic regression to assess the association between occupational exposure to PAHs and craniosynostosis. Results The prevalence of exposure was 5.3% in case mothers (16/300) and 3.7% in control mothers (107/2,886). We observed a positive association between exposure to PAHs during the one month before conception through the third month of pregnancy and craniosynostosis [odds ratio (OR) = 1.75; 95% confidence interval (CI): 1.01, 3.05] after adjusting for maternal age and maternal education. The number of cases for each craniosynostosis subtype limited subtype analyses to sagittal craniosynostosis; the odds ratio remained similar (OR = 1.76, 95% CI: 0.82–3.75), but was not significant. Conclusions Our findings support a moderate association between maternal occupational exposure to PAHs and craniosynostosis. Additional work is needed to better characterize susceptibility and the role PAHs may play on specific craniosynostosis subtypes. PMID:26033890

  19. Differences in risk factors for 2nd and 3rd degree hypospadias in the National Birth Defects Prevention Study

    PubMed Central

    in 't Woud, Sander Groen; van Rooij, Iris A.L.M.; van Gelder, Marleen M.H.J.; Olney, Richard S.; Carmichael, Suzan L.; Roeleveld, Nel; Reefhuis, Jennita

    2015-01-01

    Background Hypospadias is a frequent birth defect with three phenotypic subtypes. With data from the National Birth Defects Prevention Study, a large, multi-state, population-based, case-control study, we compared risk factors for second and third degree hypospadias. Methods A wide variety of data on maternal and pregnancy-related risk factors for isolated second and third degree hypospadias was collected via computer-assisted telephone interviews to identify potential etiological differences between the two phenotypes. Logistic regression was used to calculate odds ratios including a random effect by study center. Results In total, 1547 second degree cases, 389 third degree cases, and 5183 male controls were included in our study. Third degree cases were more likely to have a non-Hispanic black or Asian/Pacific Islander mother, be delivered preterm, have a low birth weight, be small for gestational age, and be conceived with fertility treatments than second degree cases and controls. Associations with both second and third degree hypospadias were observed for maternal age, family history, parity, plurality, and hypertension during pregnancy. Risk estimates were generally higher for third degree hypospadias except for family history. Conclusions Most risk factors were associated with both or neither phenotype. Therefore, it is likely that the underlying mechanism is at least partly similar for both phenotypes. However, some associations were different between 2nd and 3rd degree hypospadias, and went in opposite directions for second and third degree hypospadias for Asian/Pacific Islander mothers. Effect estimates for subtypes of hypospadias may be over- or underestimated in studies without stratification by phenotype. PMID:25181604

  20. Maternal occupation and the risk of major birth defects: a follow-up analysis from the National Birth Defects Prevention Study.

    PubMed

    Lin, Shao; Herdt-Losavio, Michele L; Chapman, Bonnie R; Munsie, Jean-Pierre; Olshan, Andrew F; Druschel, Charlotte M

    2013-06-01

    This study further examined the association between selected maternal occupations and a variety of birth defects identified from prior analysis and explored the effect of work hours and number of jobs held and potential interaction between folic acid and occupation. Data from a population-based, multi-center case-control study was used. Analyses included 45 major defects and specific sub-occupations under five occupational groups: healthcare workers, cleaners, scientists, teachers and personal service workers. Both logistic regression and Bayesian models (to minimize type-1 errors) were used, adjusted for potential confounders. Effect modification by folic acid was also assessed. More than any other occupation, nine different defects were positively associated with maids or janitors [odds ratio (OR) range: 1.72-3.99]. Positive associations were also seen between the following maternal occupations and defects in their children (OR range: 1.35-3.48): chemists/conotruncal heart and neural tube defects (NTDs), engineers/conotruncal defects, preschool teachers/cataracts and cleft lip with/without cleft palate (CL/P), entertainers/athletes/gastroschisis, and nurses/hydrocephalus and left ventricular outflow tract heart defects. Non-preschool teachers had significantly lower odds of oral clefts and gastroschisis in their offspring (OR range: 0.53-0.76). There was a suggestion that maternal folic acid use modified the effects with occupations including lowering the risk of NTDs and CL/P. No consistent patterns were found between maternal work hours or multiple jobs by occupation and the risk of birth defects. Overall, mothers working as maids, janitors, biologists, chemists, engineers, nurses, entertainers, child care workers and preschool teachers had increased risks of several malformations and non-preschool teachers had a lower risk of some defects. Maternal folic acid use reduced the odds of NTDs and CL/P among those with certain occupations. This hypothesis

  1. Risk factors for non-syndromic holoprosencephaly in the National Birth Defects Prevention Study.

    PubMed

    Miller, Eric A; Rasmussen, Sonja A; Siega-Riz, Anna Maria; Frías, Jaime L; Honein, Margaret A

    2010-02-15

    Holoprosencephaly (HPE) is a complex structural brain anomaly that results from incomplete cleavage of the forebrain. The prevalence of HPE at birth is low, and risk factors have been difficult to identify. Using data from a large multi-state population-based case-control study, we examined risk factors for non-syndromic HPE. Data from maternal telephone interviews were available for 74 infants with HPE and 5871 controls born between 1997 and 2004. Several characteristics and exposures were examined, including pregnancy history, medical history, maternal diet and use of nutritional supplements, medications, tobacco, alcohol, and illegal substances. We used chi(2)-tests and logistic regression (excluding women with pre-existing diabetes) to examine associations with HPE. Except for diet (year before pregnancy) and sexually transmitted infections (STIs) (throughout pregnancy), most exposures were examined for the time period from the month before to the third month of pregnancy. HPE was found to be associated with pre-existing diabetes (chi(2) = 6.0; P = 0.01), aspirin use [adjusted odds ratio (aOR) = 3.4; 95% confidence interval (CI) 1.6-6.9], lower education level (aOR = 2.5; 95%CI 1.1-5.6), and use of assisted reproductive technologies (ART) (crude OR = 4.2; 95%CI 1.3-13.7). Consistent maternal folic acid use appeared to be protective (aOR = 0.4; 95%CI 0.2-1.0), but the association was of borderline statistical significance. While some of these findings support previous observations, other potential risk factors identified warrant further study.

  2. Folic acid usage and associated factors in the prevention of neural tube defects among pregnant women in Ethiopia: cross-sectional study.

    PubMed

    Dessie, Meselech Ambaw; Zeleke, Ejigu Gebeye; Workie, Shimelash Bitew; Berihun, Ayanaw Worku

    2017-09-21

    Neural tube defects are among the most common birth defects, contributing to miscarriage, infant mortality, severe congenital abnormalities and serious disabilities. It is burdensome to patients, caregivers, healthcare systems and society. It could be reduced if women consume a folic acid supplement before and during the early weeks of pregnancy. This study assesses folic acid usage and associated factors for the prevention of neural tube defects among pregnant women in Ethiopia. Institution based cross-sectional study was conducted on 417 systematically sampled, consented pregnant women that visited Adama hospital medical college for antenatal care during August to November 2014. Pretested interviewer administered questionnaire was used to collect socio-demographic, obstetric characteristics and folic acid usage of women. About 48.4% of women took a folic acid supplement at different period of pregnancy; but, only 1.92% of women took the supplement at a protective period against neural tube defects. Age, the early timing of antenatal registration, was a preconception consulted, previous unsuccessful pregnancies and level of folic acid awareness were significantly associated with folic acid usage for prevention of neural tube defects. Folic acid usage during the protective period against neural tube defects among women in Ethiopia is very low, so healthcare plan to improve intake of folic acid is required.

  3. Hispanic ethnicity and acculturation, maternal age and the risk of gastroschisis in the National Birth Defects Prevention Study.

    PubMed

    Khodr, Zeina G; Lupo, Philip J; Canfield, Mark A; Chan, Wenyaw; Cai, Yi; Mitchell, Laura E

    2013-08-01

    Studies indicate that gastroschisis is associated with maternal age, ethnicity, and acculturation. This analysis was conducted to further define the associations between gastroschisis and parental Hispanic ethnicity and acculturation, and to determine whether such associations vary by maternal age. This study was based on data from mothers of 753 gastroschisis cases and 6,496 control infants in the National Birth Defects Prevention Study. The relationships between gastroschisis and both parental Hispanic ethnicity and acculturation, within maternal age strata (<20 versus ≥20 years at conception), were assessed using logistic regression and principal component analyses. The risk of gastroschisis in offspring of women <20 years old was not significantly associated with parental Hispanic ethnicity or acculturation. Among mothers ≥20 years old, US-born non-Hispanic white parents had a lower risk of gastroschisis in offspring as compared to either US-born Hispanic (odds ratios [ORs] ranging from 0.55 to 0.60) or English-speaking Hispanic (ORs ranging from 0.58 to 0.65) parents. Further, compared with US born Hispanic women ≥20 years, the risk of gastroschisis was lower for Hispanic women who had lived in the US <5 years (OR=0.35, 95% confidence interval [CI]: 0.17, 0.74) or who migrated to the US at ≥20 years (OR=0.47, 95% CI: 0.25, 0.88). These results provide further evidence that gastroschisis risk is associated with ethnicity and some aspects of acculturation. Additionally, these associations were limited to the offspring of women who are ≥20 at the time of conception. Copyright © 2013 Wiley Periodicals, Inc.

  4. Prevention of neural tube defects by the fortification of flour with folic acid: a population-based retrospective study in Brazil

    PubMed Central

    Lecca, Roberto Carlos Reyes; Cortez-Escalante, Juan Jose; Sanchez, Mauro Niskier; Rodrigues, Humberto Gabriel

    2016-01-01

    Abstract Objective To determine if the fortification of wheat and maize flours with iron and folic acid – which became mandatory in Brazil from June 2004 – is effective in the prevention of neural tube defects. Methods Using data from national information systems on births in central, south-eastern and southern Brazil, we determined the prevalence of neural tube defects among live births and stillbirths in a pre-fortification period – i.e. 2001–2004 – and in a post-fortification period – i.e. 2005–2014. We distinguished between anencephaly, encephalocele, meningocele, myelomeningocele and other forms of spina bifida. Findings There were 8554 neural tube defects for 17 925 729 live births notified between 2001 and 2014. For the same period, 2673 neural tube defects were reported for 194 858 stillbirths. The overall prevalence of neural tube defects fell from 0.79 per 1000 pre-fortification to 0.55 per 1000 post-fortification (prevalence ratio, PR: 1.43; 95% confidence interval, CI: 1.38–1.50). For stillbirths, prevalence fell from 17.74 per 1000 stillbirths pre-fortification to 11.70 per 1000 stillbirths post-fortification. The corresponding values among live births were 0.57 and 0.44, respectively. Conclusion The introduction of the mandatory fortification of flour with iron and folic acid in Brazil was followed by a significant reduction in the prevalence of neural tube defects in our study area. PMID:26769993

  5. [Folic acid: Primary prevention of neural tube defects. Literature Review].

    PubMed

    Llamas Centeno, M J; Miguélez Lago, C

    2016-03-01

    Neural tube defects (NTD) are the most common congenital malformations of the nervous system, they have a multifactorial etiology, are caused by exposure to chemical, physical or biological toxic agents, factors deficiency, diabetes, obesity, hyperthermia, genetic alterations and unknown causes. Some of these factors are associated with malnutrition by interfering with the folic acid metabolic pathway, the vitamin responsible for neural tube closure. Its deficit produce anomalies that can cause abortions, stillbirths or newborn serious injuries that cause disability, impaired quality of life and require expensive treatments to try to alleviate in some way the alterations produced in the embryo. Folic acid deficiency is considered the ultimate cause of the production of neural tube defects, it is clear the reduction in the incidence of Espina Bifida after administration of folic acid before conception, this leads us to want to further study the action of folic acid and its application in the primary prevention of neural tube defects. More than 40 countries have made the fortification of flour with folate, achieving encouraging data of decrease in the prevalence of neural tube defects. This paper attempts to make a literature review, which clarify the current situation and future of the prevention of neural tube defects.

  6. Paternal and joint parental occupational pesticide exposure and spina bifida in the National Birth Defects Prevention Study, 1997 to 2002.

    PubMed

    Pettigrew, Stacy M; Bell, Erin M; Van Zutphen, Alissa R; Rocheleau, Carissa M; Shaw, Gary M; Romitti, Paul A; Olshan, Andrew; Lupo, Philip J; Soim, Aida; Makelarski, Jennifer A; Michalski, Adrian M; Sanderson, Wayne

    2016-11-01

    Because of persistent concerns over the association between pesticides and spina bifida, we examined the role of paternal and combined parental occupational pesticide exposures in spina bifida in offspring using data from a large population-based study of birth defects. Occupational information from fathers of 291 spina bifida cases and 2745 unaffected live born control infants with estimated dates of delivery from 1997 to 2002 were collected by means of maternal report. Two expert industrial hygienists estimated exposure intensity and frequency to insecticides, herbicides, and fungicides. Multivariable logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for exposure to any pesticide and to any class of pesticide (yes/no; and by median), and exposure to combinations of pesticides (yes/no) and risk of spina bifida. Adjusted odds ratios were also estimated by parent exposed to pesticides (neither, mother only, father only, both parents). Joint parental occupational pesticide exposure was positively associated with spina bifida (aOR, 1.5; 95% CI, 0.9-2.4) when compared with infants with neither maternal nor paternal exposures; a similar association was not observed when only one parent was exposed. There was a suggested positive association between combined paternal insecticide and fungicide exposures and spina bifida (aOR, 1.5; 95% CI, 0.8-2.8), however, nearly all other aORs were close to unity. Overall, there was little evidence paternal occupational pesticide exposure was associated with spina bifida. However, the small numbers make it difficult to precisely evaluate the role of pesticide classes, individually and in combination. Birth Defects Research (Part A) 106:963-971, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Folic acid and birth defect prevention

    MedlinePlus

    ... Women who have had a baby with a neural tube defect may need a higher dose of folic acid. If you have had a baby with a neural tube defect, you should take 400 micrograms of folic acid every day, even when you are not planning ...

  8. Assessment of risk factors for infantile cataracts using a case-control study: National Birth Defects Prevention Study, 2000-2004.

    PubMed

    Prakalapakorn, Sasapin G; Rasmussen, Sonja A; Lambert, Scott R; Honein, Margaret A

    2010-08-01

    To identify risk factors for infantile cataracts of unknown etiology. Case-control study. Case infants (n = 152) and control infants (n = 4205) enrolled in the National Birth Defects Prevention Study for birth years 2000-2004. Multivariate analysis was performed exploring associations for risk factors for bilateral and unilateral infantile cataracts of unknown etiology. Infantile cataracts of unknown etiology. Maternal interviews were completed for 43 case infants with bilateral and 109 with unilateral infantile cataracts of unknown etiology. Very low birth weight (<1500 g) was associated with both unilateral (adjusted odds ratio [OR], 6.0; 95% confidence interval [CI], 2.2-16.3) and bilateral (OR, 13.2; 95% CI, 4.2-41.1) cataracts, whereas low birth weight (1500-2499 g) was only associated with bilateral cataracts (OR, 3.3; 95% CI, 1.3-8.1). Infants with unilateral cataracts were more likely to be born to primigravid women (OR, 1.6; 95% CI, 1.0-2.7) than women with > or =2 previous pregnancies, although this was of borderline significance. Although not significant, effect estimates were elevated suggesting a possible association between unilateral cataracts and maternal substance abuse during pregnancy, and between bilateral cataracts and urinary tract infection during pregnancy and aspirin use during pregnancy. Very low birth weight is associated with both bilateral and unilateral cataracts, whereas low birth weight is associated with bilateral cataracts and primigravidity with unilateral cataracts. Other associations, although not statistically significant, suggest risk factors that merit further research. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  9. Assessment of risk factors for infantile cataracts using a case-control study, National Birth Defects Prevention Study, 2000–2004

    PubMed Central

    Prakalapakorn, Sasapin G.; Rasmussen, Sonja A.; Lambert, Scott R.; Honein, Margaret A.

    2010-01-01

    Objective To identify risk factors for infantile cataracts of unknown etiology. Design Case-control study Participants Case-infants (N=152) and control-infants (N=4205) enrolled in the National Birth Defects Prevention Study for birth years 2000–2004. Methods Multivariate analysis was performed exploring associations for risk factors for bilateral and unilateral infantile cataracts of unknown etiology. Main Outcome Measures Infantile cataracts of unknown etiology Results Maternal interviews were completed for 43 case-infants with bilateral and 109 with unilateral infantile cataracts of unknown etiology. Very low birth weight (<1500g) was associated with both unilateral (adjusted odds ratio [OR]=6.0; 95% confidence interval [CI]=2.2–16.3) and bilateral (OR=13.2; 95% CI=4.2–41.1) cataracts, while low birth weight (1500–2499g) was only associated with bilateral cataracts (OR=3.3; 95% CI=1.3–8.1). Infants with unilateral cataracts were more likely to be born to primigravid women (OR=1.6; 95% CI=1.0–2.7) than women with two or more previous pregnancies, although this was of borderline significance. While not statistically significant, effect estimates were elevated suggesting a possible association between unilateral cataracts and maternal substance abuse during pregnancy, and between bilateral cataracts and urinary tract infection during pregnancy and aspirin use during pregnancy. Conclusions Very low birth weight is associated with both bilateral and unilateral cataracts, while low birth weight is associated with bilateral cataracts and primigravidity with unilateral cataracts. Other associations, while not of statistical significance, suggest risk factors that merit further research. PMID:20363508

  10. A Prescription for the Prevention of Birth Defects.

    ERIC Educational Resources Information Center

    Slavkin, Harold C.

    1984-01-01

    Factors influencing birth defects include maternal age (teenagers and women over 32 are at risk), genetics, drug use, diet habits, and environmental hazards. The physical, social, and economic costs of birth defects are extreme. Prevention must involve efforts to change some of these factors. (Author/CS)

  11. Investigation of scum type growing defects on attenuated PSM and its prevention

    NASA Astrophysics Data System (ADS)

    Choi, Jihwan; Kim, Yongho; Lee, Dongwook; Jung, Hoyong; Kim, Snagpyo; Yim, Donggyu

    2015-10-01

    The abnormal growing defect (we called this defect 'scum haze defect') in the photomask which is generated during the wafer lithography process is very important issue on semiconductor industry. Because wafer yield loss could be caused by the mask CD variation and the transmittance loss due to the growing defects on the photomask, many studies have been done about the mechanism and the solution of the general type growing defects such as haze and Cr migration so far, However we still need to clarify some abnormal types of the growing defects such as scum haze defect. In this paper, we investigated the generation mechanism and prevention techniques of the scum haze defect on the attenuated phase shift mask. This defect composed of CrOx is caused by the increase of the accumulated exposure energy on photomask. This phenomenon is remarkably similar to the Cr migration on binary mask. But, the apparent difference is that this scum type defect is observed on the attenuated phase shift mask which mainly consists of MoSiON film, and it is difficult to control this defect because of its irregular generation characteristic. Additionally, this defect is not generally removed through the conventional wet cleaning process but it only could be removed by a kind of plasma treatment. In this study, the difference of generation mechanism between the scum haze defect and the general haze was discussed, and the optimal process for controlling scum haze defect in the mask manufacturing was described.

  12. Systems Biology and Birth Defects Prevention: Blockade of the Glucocorticoid Receptor Prevents Arsenic-Induced Birth Defects

    PubMed Central

    Ahir, Bhavesh K.; Sanders, Alison P.; Rager, Julia E.

    2013-01-01

    Background: The biological mechanisms by which environmental metals are associated with birth defects are largely unknown. Systems biology–based approaches may help to identify key pathways that mediate metal-induced birth defects as well as potential targets for prevention. Objectives: First, we applied a novel computational approach to identify a prioritized biological pathway that associates metals with birth defects. Second, in a laboratory setting, we sought to determine whether inhibition of the identified pathway prevents developmental defects. Methods: Seven environmental metals were selected for inclusion in the computational analysis: arsenic, cadmium, chromium, lead, mercury, nickel, and selenium. We used an in silico strategy to predict genes and pathways associated with both metal exposure and developmental defects. The most significant pathway was identified and tested using an in ovo whole chick embryo culture assay. We further evaluated the role of the pathway as a mediator of metal-induced toxicity using the in vitro midbrain micromass culture assay. Results: The glucocorticoid receptor pathway was computationally predicted to be a key mediator of multiple metal-induced birth defects. In the chick embryo model, structural malformations induced by inorganic arsenic (iAs) were prevented when signaling of the glucocorticoid receptor pathway was inhibited. Further, glucocorticoid receptor inhibition demonstrated partial to complete protection from both iAs- and cadmium-induced neurodevelopmental toxicity in vitro. Conclusions: Our findings highlight a novel approach to computationally identify a targeted biological pathway for examining birth defects prevention. PMID:23458687

  13. Demographic characteristics, care, and outcomes for children with oral clefts in three states using participants from the National Birth Defects Prevention Study.

    PubMed

    Damiano, Peter; Tyler, Margaret; Romitti, Paul A; Druschel, Charlotte; Austin, April A; Burnett, Whitney; Kizelnik-Freilich, Sara; Robbins, James M

    2009-11-01

    The primary objective of this study was to evaluate whether there were differences in the characteristics and outcomes of care for children with oral clefts (OCs) among population-based samples in three states. Data on the health status and on speech and esthetic outcomes were collected using structured telephone interviews conducted during 2005-2006 with mothers of children with OCs aged 2 to 7 in Arkansas, Iowa, and New York. Mothers of children born with nonsyndromic OCs on or after January 1, 1998, and on or before December 31, 2003, in Arkansas, Iowa, or New York. Subjects were identified through their participation in the ongoing National Birth Defects Prevention Study. Demographic characteristics, rating of cleft care, severity of condition, health status, esthetic outcomes, and speech problems were evaluated by state of residence. Children with OCs from Arkansas were from lower income families, and their parents were less likely to be married. Children with OCs from Arkansas were more likely to have special health care needs and to require mental health care. Few differences were found across states in type of cleft, severity of cleft, or outcomes of cleft care. Combining results from population-based samples across multiple studies increases the variability of sample characteristics. Including multiple states can be an efficient way to learn more about the outcomes of medical care for less common conditions such as oral cleft.

  14. Knowledge and use of folic acid for birth defect prevention among women of childbearing age in Shanghai, China: a prospective cross-sectional study.

    PubMed

    Lian, Huan; Ma, Duan; Zhou, Shu-Feng; Li, Xiaotian

    2011-12-01

    This study aimed to assess the knowledge, attitude, and practice of folic acid intake for prevention of birth defects in Chinese women of child-bearing age. In this prospective cross-sectional study, a total of 1,338 women aged 20-45 years were randomly selected for interview. Data on folic acid knowledge and information on folic acid intake in the subjects were collected. Age, education, contraception, and status of family planning were used as the independent variables in multivariate logistic regression. 55.6% of the subjects took contraception at all times, and 33.9% had pregnancy planning in the next six months. 49.7% of the interviewed women knew the benefits of folic acid and 34.6% realized the correct time of folic acid intake; and 14.9% of these women actually took folic acid daily. Planning to be pregnant in the next six months was associated with knowledge of folic acid benefits, correct time of folic acid intake and actual intake. A higher education level was correlated with the knowledge of folic acid benefits and correct time of folic acid intake, but was not linked to actual intake of folic acid. The knowledge and use of folic acid were at low to moderate levels in women at childbearing age in Shanghai, China, and general knowledge of folic acid benefits and correct time of folic acid intake should be conveyed to these women.

  15. Agreement between two methods for retrospective assessment of occupational exposure intensity to six chlorinated solvents: Data from The National Birth Defects Prevention Study.

    PubMed

    Johnson, Candice Y; Rocheleau, Carissa M; Hein, Misty J; Waters, Martha A; Stewart, Patricia A; Lawson, Christina C; Reefhuis, Jennita

    2017-05-01

    The wide variety of jobs encountered in population-based studies makes retrospective exposure assessment challenging in occupational epidemiology. In this analysis, two methods for estimating exposure intensity to chlorinated solvents are compared: rated (assigned by an expert rater) and modeled (assigned using statistical models). Estimates of rated and modeled intensities were compared for jobs held by mothers participating in the National Birth Defects Prevention Study with possible exposure to six chlorinated solvents: carbon tetrachloride, chloroform, methylene chloride, perchloroethylene, 1,1,1-trichloroethane, and trichloroethylene. For each possibly exposed job, an industrial hygienist assigned (1) an exposure intensity (rated intensity) and (2) determinants of exposure to be used in a statistical model of exposure intensity (modeled intensity). Of 12,326 reported jobs, between 31 (0.3%) and 746 (6%) jobs were rated as possibly exposed to each of the six solvents. Agreement between rated and modeled intensities was low overall (Spearman correlation coefficient range: -0.09 to 0.28; kappa range: -0.23 to 0.43). Although no air measurements were available to determine if rated or modeled estimates were more accurate, review of participants' job titles showed that modeled estimates were often unexpectedly high given the low-exposure tasks found in these jobs. Differences between the high-exposure jobs used to create the statistical models (obtained from air measurements in the published literature) and the low-exposure jobs in the actual study population is a potential explanation for the disagreement between the two methods. Investigators should be aware that statistical models estimating exposure intensity using existing data from one type of worker population might not be generalizable to all populations of workers.

  16. Who Should Be Targeted for the Prevention of Birth Defects? A Latent Class Analysis Based on a Large, Population-Based, Cross-Sectional Study in Shaanxi Province, Western China

    PubMed Central

    Yang, Wenfang; Li, Danyang; Yang, Xue; Liu, Danli; Zhang, Min; Yan, Hong; Zeng, Lingxia

    2016-01-01

    Background The wide range and complex combinations of factors that cause birth defects impede the development of primary prevention strategies targeted at high-risk subpopulations. Methods Latent class analysis (LCA) was conducted to identify mutually exclusive profiles of factors associated with birth defects among women between 15 and 49 years of age using data from a large, population-based, cross-sectional study conducted in Shaanxi Province, western China, between August and October, 2013. The odds ratios (ORs) and 95% confidence intervals (CIs) of associated factors and the latent profiles of indicators of birth defects and congenital heart defects were computed using a logistic regression model. Results Five discrete subpopulations of participants were identified as follows: No folic acid supplementation in the periconceptional period (reference class, 21.37%); low maternal education level + unhealthy lifestyle (class 2, 39.75%); low maternal education level + unhealthy lifestyle + disease (class 3, 23.71%); unhealthy maternal lifestyle + advanced age (class 4, 4.71%); and multi-risk factor exposure (class 5, 10.45%). Compared with the reference subgroup, the other subgroups consistently had a significantly increased risk of birth defects (ORs and 95% CIs: class 2, 1.75 and 1.21–2.54; class 3, 3.13 and 2.17–4.52; class 4, 5.02 and 3.20–7.88; and class 5, 12.25 and 8.61–17.42, respectively). For congenital heart defects, the ORs and 95% CIs were all higher, and the magnitude of OR differences ranged from 1.59 to 16.15. Conclusions A comprehensive intervention strategy targeting maternal exposure to multiple risk factors is expected to show the strongest results in preventing birth defects. PMID:27183231

  17. Who Should Be Targeted for the Prevention of Birth Defects? A Latent Class Analysis Based on a Large, Population-Based, Cross-Sectional Study in Shaanxi Province, Western China.

    PubMed

    Zhu, Zhonghai; Cheng, Yue; Yang, Wenfang; Li, Danyang; Yang, Xue; Liu, Danli; Zhang, Min; Yan, Hong; Zeng, Lingxia

    2016-01-01

    The wide range and complex combinations of factors that cause birth defects impede the development of primary prevention strategies targeted at high-risk subpopulations. Latent class analysis (LCA) was conducted to identify mutually exclusive profiles of factors associated with birth defects among women between 15 and 49 years of age using data from a large, population-based, cross-sectional study conducted in Shaanxi Province, western China, between August and October, 2013. The odds ratios (ORs) and 95% confidence intervals (CIs) of associated factors and the latent profiles of indicators of birth defects and congenital heart defects were computed using a logistic regression model. Five discrete subpopulations of participants were identified as follows: No folic acid supplementation in the periconceptional period (reference class, 21.37%); low maternal education level + unhealthy lifestyle (class 2, 39.75%); low maternal education level + unhealthy lifestyle + disease (class 3, 23.71%); unhealthy maternal lifestyle + advanced age (class 4, 4.71%); and multi-risk factor exposure (class 5, 10.45%). Compared with the reference subgroup, the other subgroups consistently had a significantly increased risk of birth defects (ORs and 95% CIs: class 2, 1.75 and 1.21-2.54; class 3, 3.13 and 2.17-4.52; class 4, 5.02 and 3.20-7.88; and class 5, 12.25 and 8.61-17.42, respectively). For congenital heart defects, the ORs and 95% CIs were all higher, and the magnitude of OR differences ranged from 1.59 to 16.15. A comprehensive intervention strategy targeting maternal exposure to multiple risk factors is expected to show the strongest results in preventing birth defects.

  18. Prevention of medical accidents caused by defective surgical instruments.

    PubMed

    Yasuhara, Hiroshi; Fukatsu, Kazuhiko; Komatsu, Takami; Obayashi, Toshihiko; Saito, Yuhei; Uetera, Yushi

    2012-02-01

    The malfunctioning of surgical instruments may lead to serious medical accidents. Limited information is available on the risk of defective instruments. The purpose of these study is to demonstrate the features of defective surgical instruments, to establish a strategy to reduce the risk of medical accidents. We studied 19,474 consecutive operations during 2007 to 2009 at our hospital. The data on defective instruments were collected based on the orders for repair of broken instruments and reports of near-miss incidents. Adverse events caused by defective instruments were also identified from reports of near-miss incidents. A total of 1,775 nonfunctioning instruments were identified during the study period. Of these, 112 were found during operation. More than half of the defective instruments were tissue-grasping instruments, bone-boring/gnawing instruments, and instruments for endoscopic surgery. Wearing out and inappropriate use of instruments were 2 major causes of defects. The rest of the causes consisted of inadequate inspection and factory defects. Two near-miss incidents (incidence 10 per 100,000 operations) in endoscopic surgery were potentially critical, but the postoperative course was uneventful in each patient. The incidence of defects adjusted by the number of operations demonstrated that bone-boring/gnawing instruments and instruments for endoscopic surgery tend to be broken during surgery. Without inspection by the manufacturer, the incidence would be much higher for endoscopic instruments. Our data suggest that the appropriate use and adequate inspection of particular types of instruments are key for reducing the risk of medical accidents caused by defective surgical instruments. Copyright © 2012 Mosby, Inc. All rights reserved.

  19. Enzyme replacement prevents enamel defects in hypophosphatasia mice

    PubMed Central

    Yadav, Manisha C.; de Oliveira, Rodrigo Cardoso; Foster, Brian L.; Fong, Hanson; Cory, Esther; Narisawa, Sonoko; Sah, Robert L.; Somerman, Martha; Whyte, Michael P.; Millán, José Luis

    2012-01-01

    Hypophosphatasia (HPP) is the inborn error of metabolism characterized by deficiency of alkaline phosphatase activity leading to rickets or osteomalacia and to dental defects. HPP occurs from loss-of-function mutations within the gene that encodes the tissue-nonspecific isozyme of alkaline phosphatase (TNAP). TNAP knockout (Alpl−/−, a.k.a. Akp2−/−) mice closely phenocopy infantile HPP, including the rickets, vitamin B6-responsive seizures, improper dentin mineralization, and lack of acellular cementum. Here, we report that lack of TNAP in Alpl−/− mice also causes severe enamel defects, which are preventable by enzyme replacement with mineral-targeted TNAP (ENB-0040). Immunohistochemistry was used to map the spatiotemporal expression of TNAP in the tissues of the developing enamel organ of healthy mouse molars and incisors. We found strong, stage-specific expression of TNAP in ameloblasts. In the Alpl−/− mice, histological, μCT, and scanning electron microscopy analysis showed reduced mineralization and disrupted organization of the rods and inter-rod structures in enamel of both the molars and incisors. All of these abnormalities were prevented in mice receiving from birth daily subcutaneous injections of mineral-targeting, human TNAP (sALP-FcD10, a.k.a. ENB-0040) at 8.2 mg/kg/day for up to 44 days. These data reveal an important role for TNAP in enamel mineralization, and demonstrate the efficacy of mineral-targeted TNAP to prevent enamel defects in HPP. PMID:22461224

  20. Prevention of congenital defects induced by prenatal alcohol exposure (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sheehan, Megan M.; Karunamuni, Ganga; Pedersen, Cameron J.; Gu, Shi; Doughman, Yong Qiu; Jenkins, Michael W.; Watanabe, Michiko; Rollins, Andrew M.

    2017-02-01

    Nearly 2 million women in the United States alone are at risk for an alcohol-exposed pregnancy, including more than 600,000 who binge drink. Even low levels of prenatal alcohol exposure (PAE) can lead to a variety of birth defects, including craniofacial and neurodevelopmental defects, as well as increased risk of miscarriages and stillbirths. Studies have also shown an interaction between drinking while pregnant and an increase in congenital heart defects (CHD), including atrioventricular septal defects and other malformations. We have previously established a quail model of PAE, modeling a single binge drinking episode in the third week of a woman's pregnancy. Using optical coherence tomography (OCT), we quantified intraventricular septum thickness, great vessel diameters, and atrioventricular valve volumes. Early-stage ethanol-exposed embryos had smaller cardiac cushions (valve precursors) and increased retrograde flow, while late-stage embryos presented with gross head/body defects, and exhibited smaller atrio-ventricular (AV) valves, interventricular septum, and aortic vessels. We previously showed that supplementation with the methyl donor betaine reduced gross defects, improved survival rates, and prevented cardiac defects. Here we show that these preventative effects are also observed with folate (another methyl donor) supplementation. Folate also appears to normalize retrograde flow levels which are elevated by ethanol exposure. Finally, preliminary findings have shown that glutathione, a crucial antioxidant, is noticeably effective at improving survival rates and minimizing gross defects in ethanol-exposed embryos. Current investigations will examine the impact of glutathione supplementation on PAE-related CHDs.

  1. Study of lattice defect vibration

    NASA Technical Reports Server (NTRS)

    Elliott, R. J.

    1969-01-01

    Report on the vibrations of defects in crystals relates how defects, well localized in a crystal but interacting strongly with the other atoms, change the properties of a perfect crystal. The methods used to solve defect problems relate the properties of an imperfect lattice to the properties of a perfect lattice.

  2. Population red blood cell folate concentrations for prevention of neural tube defects: bayesian model

    PubMed Central

    Devine, Owen; Hao, Ling; Dowling, Nicole F; Li, Song; Molloy, Anne M; Li, Zhu; Zhu, Jianghui; Berry, Robert J

    2014-01-01

    Objective To determine an optimal population red blood cell (RBC) folate concentration for the prevention of neural tube birth defects. Design Bayesian model. Setting Data from two population based studies in China. Participants 247 831 participants in a prospective community intervention project in China (1993-95) to prevent neural tube defects with 400 μg/day folic acid supplementation and 1194 participants in a population based randomized trial (2003-05) to evaluate the effect of folic acid supplementation on blood folate concentration among Chinese women of reproductive age. Intervention Folic acid supplementation (400 μg/day). Main outcome measures Estimated RBC folate concentration at time of neural tube closure (day 28 of gestation) and risk of neural tube defects. Results Risk of neural tube defects was high at the lowest estimated RBC folate concentrations (for example, 25.4 (95% uncertainty interval 20.8 to 31.2) neural tube defects per 10 000 births at 500 nmol/L) and decreased as estimated RBC folate concentration increased. Risk of neural tube defects was substantially attenuated at estimated RBC folate concentrations above about 1000 nmol/L (for example, 6 neural tube defects per 10 000 births at 1180 (1050 to 1340) nmol/L). The modeled dose-response relation was consistent with the existing literature. In addition, neural tube defect risk estimates developed using the proposed model and population level RBC information were consistent with the prevalence of neural tube defects in the US population before and after food fortification with folic acid. Conclusions A threshold for “optimal” population RBC folate concentration for the prevention of neural tube defects could be defined (for example, approximately 1000 nmol/L). Population based RBC folate concentrations, as a biomarker for risk of neural tube defects, can be used to facilitate evaluation of prevention programs as well as to identify subpopulations at elevated risk for a neural

  3. Epidemiology, prenatal management, and prevention of neural tube defects

    PubMed Central

    Salih, Mustafa A.; Murshid, Waleed R.; Seidahmed, Mohammed Z.

    2014-01-01

    This review article discusses the epidemiology, risk factors, prenatal screening, diagnosis, prevention potentials, and epidemiologic impact of neural tube defects (NTDs). The average incidence of NTDs is 1/1000 births, with a marked geographic variation. In the developed countries, the incidence of NTDs has fallen over recent decades. However, it still remains high in the less-developed countries in Latin America, Africa, the Middle East, Asia, and the Far East (>1 to 11/1000 births). Recognized NTDs risks include maternal diabetes, obesity, lower socioeconomic status, hyperthermia, and exposure to certain teratogens during the periconceptional period. Periconceptional folic acid supplementation decreased the prevalence of NTDs by 50-70%, and an obligatory folic acid fortification of food was adopted in several countries to reach women with unplanned pregnancies and those facing social deprivation. Prevention of NTDs can be accelerated if more, especially low income countries, adopted fortification of the staple food in their communities. PMID:25551106

  4. Defect Prevention and Detection in Software for Automated Test Equipment

    SciTech Connect

    E. Bean

    2006-11-30

    Software for automated test equipment can be tedious and monotonous making it just as error-prone as other software. Active defect prevention and detection are also important for test applications. Incomplete or unclear requirements, a cryptic syntax used for some test applications—especially script-based test sets, variability in syntax or structure, and changing requirements are among the problems encountered in one tester. Such problems are common to all software but can be particularly problematic in test equipment software intended to test another product. Each of these issues increases the probability of error injection during test application development. This report describes a test application development tool designed to address these issues and others for a particular piece of test equipment. By addressing these problems in the development environment, the tool has powerful built-in defect prevention and detection capabilities. Regular expressions are widely used in the development tool as a means of formally defining test equipment requirements for the test application and verifying conformance to those requirements. A novel means of using regular expressions to perform range checking was developed. A reduction in rework and increased productivity are the results. These capabilities are described along with lessons learned and their applicability to other test equipment software. The test application development tool, or “application builder”, is known as the PT3800 AM Creation, Revision and Archiving Tool (PACRAT).

  5. Data linkage between the National Birth Defects Prevention Study and the Occupational Information Network (O*NET) to assess workplace physical activity, sedentary behaviors, and emotional stressors during pregnancy.

    PubMed

    Lee, Laura J; Symanski, Elaine; Lupo, Philip J; Tinker, Sarah C; Razzaghi, Hilda; Pompeii, Lisa A; Hoyt, Adrienne T; Canfield, Mark A; Chan, Wenyaw

    2016-02-01

    Knowledge of the prevalence of work-related physical activities, sedentary behaviors, and emotional stressors among pregnant women is limited, and the extent to which these exposures vary by maternal characteristics remains unclear. Data on mothers of 6,817 infants without major birth defects, with estimated delivery during 1997 through 2009 who worked during pregnancy were obtained from the National Birth Defects Prevention Study. Information on multiple domains of occupational exposures was gathered by linking mother's primary job to the Occupational Information Network Version 9.0. The most frequent estimated physical activity associated with jobs during pregnancy was standing. Of 6,337 mothers, 31.0% reported jobs associated with standing for ≥75% of their time. There was significant variability in estimated occupational exposures by maternal age, race/ethnicity, and educational level. Our findings augment existing literature on occupational physical activities, sedentary behaviors, emotional stressors, and occupational health disparities during pregnancy. © 2015 Wiley Periodicals, Inc.

  6. Folate deficiency and folic acid supplementation: the prevention of neural-tube defects and congenital heart defects.

    PubMed

    Czeizel, Andrew E; Dudás, Istvan; Vereczkey, Attila; Bánhidy, Ferenc

    2013-11-21

    Diet, particularly vitamin deficiency, is associated with the risk of birth defects. The aim of this review paper is to show the characteristics of common and severe neural-tube defects together with congenital heart defects (CHD) as vitamin deficiencies play a role in their origin. The findings of the Hungarian intervention (randomized double-blind and cohort controlled) trials indicated that periconceptional folic acid (FA)-containing multivitamin supplementation prevented the major proportion (about 90%) of neural-tube defects (NTD) as well as a certain proportion (about 40%) of congenital heart defects. Finally the benefits and drawbacks of three main practical applications of folic acid/multivitamin treatment such as (i) dietary intake; (ii) periconceptional supplementation; and (iii) flour fortification are discussed. The conclusion arrived at is indeed confirmation of Benjamin Franklin's statement: "An ounce of prevention is better than a pound of care".

  7. Folate Deficiency and Folic Acid Supplementation: The Prevention of Neural-Tube Defects and Congenital Heart Defects

    PubMed Central

    Czeizel, Andrew E.; Dudás, Istvan; Vereczkey, Attila; Bánhidy, Ferenc

    2013-01-01

    Diet, particularly vitamin deficiency, is associated with the risk of birth defects. The aim of this review paper is to show the characteristics of common and severe neural-tube defects together with congenital heart defects (CHD) as vitamin deficiencies play a role in their origin. The findings of the Hungarian intervention (randomized double-blind and cohort controlled) trials indicated that periconceptional folic acid (FA)-containing multivitamin supplementation prevented the major proportion (about 90%) of neural-tube defects (NTD) as well as a certain proportion (about 40%) of congenital heart defects. Finally the benefits and drawbacks of three main practical applications of folic acid/multivitamin treatment such as (i) dietary intake; (ii) periconceptional supplementation; and (iii) flour fortification are discussed. The conclusion arrived at is indeed confirmation of Benjamin Franklin’s statement: “An ounce of prevention is better than a pound of care”. PMID:24284617

  8. Utility of Deep Inspiration Breath Hold for Left-Sided Breast Radiation Therapy in Preventing Early Cardiac Perfusion Defects: A Prospective Study.

    PubMed

    Zagar, Timothy M; Kaidar-Person, Orit; Tang, Xiaoli; Jones, Ellen E; Matney, Jason; Das, Shiva K; Green, Rebecca L; Sheikh, Arif; Khandani, Amir H; McCartney, William H; Oldan, Jorge Daniel; Wong, Terence Z; Marks, Lawrence B

    2017-04-01

    To evaluate early cardiac single photon computed tomography (SPECT) findings after left breast/chest wall postoperative radiation therapy (RT) in the setting of deep inspiration breath hold (DIBH). We performed a prospective single-institution single-arm study of patients who were planned for tangential RT with DIBH to the left breast/chest wall (± internal mammary nodes). The DIBH was done by use of a controlled surface monitoring technique (AlignRT, Vision RT Ltd, London, UK). The RT was given with tangential fields and a heart block. Radiation-induced cardiac perfusion and wall motion changes were assessed by pre-RT and 6-month post-RT SPECT scans. A cumulative SPECT summed-rest score was used to quantify perfusion in predefined left ventricle segments. The incidence of wall motion abnormalities was assessed in each of these same segments. A total of 20 patients with normal pre-RT scans were studied; their median age was 56 years (range, 39-72 years). Seven (35%) patients also received irradiation to the left internal mammary chain, and 5 (25%) received an additional RT field to supraclavicular nodes. The median heart dose was 94 cGy (range, 56-200 cGy), and the median V25Gy was zero (range, 0-0.1). None of the patients had post-RT perfusion or wall motion abnormalities. Our results suggest that DIBH and conformal cardiac blocking for patients receiving tangential RT for left-sided breast cancer is an effective means to avoid early RT-associated cardiac perfusion defects. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Reevaluation of Antioxidative Strategies for Birth Defect Prevention in Diabetic Pregnancies.

    PubMed

    Zhao, Zhiyong

    2016-09-01

    Diabetes mellitus in early pregnancy is the most severe maternal disease that is counted for 10% of newborn infants with structural defects. With the rapid increases in the number of diabetic women in childbearing age, the birth defect rate is projected to elevate dramatically. Thus, prevention of embryonic malformations becomes an urgent task. Animal studies have revealed an involvement of oxidative stress in diabetic embryopathy and treatment with antioxidants can reduce embryonic abnormalities. However, the failure of clinical trials using free radical-scavenging antioxidants to alleviate oxidative stress-related diseases prompts researchers to reevaluate the strategy in birth defect prevention. Hyperglycemia also disturbs other intracellular homeostasis, generating aberrant conditions. Perturbed folding of newly synthesized proteins causes accumulation of unfolded and misfolded proteins in the lumen of the endoplasmic reticulum (ER). The ER under the stress activates signaling cascades, known as unfolded protein response, to suppress cell mitosis and/or trigger apoptosis. ER stress can be ameliorated by chemical chaperones, which promote protein folding. Hyperglycemia also stimulates the expression of nitric oxide (NO) synthase 2 (NOS2) to produce high levels of NO and reactive nitrogen species and augment protein nitrosylation and nitration, resulting in nitrosative stress. Inhibition of NOS2 using inhibitors has been demonstrated to reduce embryonic malformations in diabetic animals. Therefore, targeting ER and nitrosative stress conditions using specific agents to prevent birth defects in diabetic pregnancies warrant further investigations. Simultaneously targeting multiple stress conditions using combined agents is a potentially effective and feasible approach.

  10. Effects and safety of periconceptional folate supplementation for preventing birth defects

    PubMed Central

    Maria De-Regil, Luz; Fernández-Gaxiola, Ana C; Dowswell, Therese; Peña-Rosas, Juan Pablo

    2014-01-01

    Background It has been reported that neural tube defects can be prevented with periconceptional folic acid supplementation. The effects of different doses, forms and schemes of folate supplementation for the prevention of other birth defects and maternal and infant outcomes are unclear. Objectives This review updates and expands a previous Cochrane Review assessing the effects of periconceptional supplementation with folic acid to reduce neural tube defects (NTDs). We examined whether folate supplementation before and during early pregnancy can reduce neural tube and other birth defects (including cleft palate) without causing adverse outcomes for mothers or babies. Search methods We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (July 2010). Additionally, we searched the international clinical trials registry platform and contacted relevant organisations to identify ongoing and unpublished studies. Selection criteria We included all randomised or quasi-randomised trials evaluating the effect of periconceptional folate supplementation alone, or in combination with other vitamins and minerals, in women independent of age and parity. Data collection and analysis We assessed trials for methodological quality using the standard Cochrane criteria. Two authors independently assessed the trials for inclusion, one author extracted data and a second checked for accuracy. Main results Five trials involving 6105 women (1949 with a history of a pregnancy affected by a NTD and 4156 with no history of NTDs) were included. Overall, the results are consistent in showing a protective effect of daily folic acid supplementation (alone or in combination with other vitamins and minerals) in preventing NTDs compared with no interventions/placebo or vitamins and minerals without folic acid (risk ratio (RR) 0.28, 95% confidence interval (CI) 0.15 to 0.52). Only one study assessed the incidence of NTDs and the effect was not statistically significant (RR 0.08, 95

  11. Preventing birth defects: The value of the NBDPS case-control approach.

    PubMed

    Dolk, Helen

    2015-08-01

    Birth Defect Registries provide a basis for epidemiological research into risk factors, thus facilitating a growing understanding of what causes congenital anomalies and how one might target preventive public health actions and reduce inequalities. The National Birth Defects Prevention Study (NBDPS) has used 10 U.S. registries as a basis for a large case-control study. This commentary reviews its methodology and selected areas of output. The strengths of NBDPS lie in the quality of diagnostic coding and classification of birth defects and its size. The sources of bias in NBDPS data relate particularly to retrospective exposure ascertainment entailing a long period of recall, incomplete ascertainment of terminations of pregnancy for fetal anomaly, and unknown bias in case selection. NBDPS results have shown the protective effect of healthy dietary patterns, but have not been as informative as expected in relation to furthering understanding of the protective effect of folic acid. NBDPS medication studies are making important contributions to addressing the gap in existing evidence systematically across a wide range of birth defects, but are challenged by the quality of information on exposure, dose and underlying disease condition, and the interpretation of results of multiple testing. Studies of environmental contaminants in collaboration with experts in exposure assessment have linked addresses to residential exposure measures, using the advantages of information on residential history and confounders, but are challenged by the need to consider exposure mixtures. NBDPS could increase its public health impact by placing more emphasis on socioeconomic inequalities.

  12. Prevention of Neural Tube Defects. ARC Q&A #101-45.

    ERIC Educational Resources Information Center

    Arc, Arlington, TX.

    This fact sheet uses a question-and-answer format to summarize issues related to the prevention of neural tube defects. Questions and answers address the following topics: what neural tube defects are and the most common types (spina bifida and anencephaly); occurrence of neural tube defects during the first month of pregnancy; the frequency of…

  13. Prevention of Neural Tube Defects. ARC Q&A #101-45.

    ERIC Educational Resources Information Center

    Arc, Arlington, TX.

    This fact sheet uses a question-and-answer format to summarize issues related to the prevention of neural tube defects. Questions and answers address the following topics: what neural tube defects are and the most common types (spina bifida and anencephaly); occurrence of neural tube defects during the first month of pregnancy; the frequency of…

  14. Human neural tube defects: genetic causes and prevention.

    PubMed

    De Marco, Patrizia; Merello, Elisa; Cama, Armando; Kibar, Zoha; Capra, Valeria

    2011-01-01

    Neural tube defects (NTDs) are severe congenital malformations affecting 1-2 in 1,000 live births, whose etiology is multifactorial, involving environmental and genetic factors. NTDs arise as consequence of the failure of fusion of the neural tube early during embryogenesis. NTDs' pathogenesis has been linked to genes involved in folate metabolism, consistent with an epidemiologic evidence that 70% of NTDs can be prevented by maternal periconceptional supplementation. However, polymorphisms in such genes are not linked in all populations, suggesting that other genetic factors and environmental factors could be involved. Animal models have provided crucial mechanistic information and possible candidate genes to explain susceptibility to NTDs. A crucial role has been assigned to the planar cell polarity (PCP) pathway, a highly conserved, non-canonical Wnt-frizzled-dishevelled signaling cascade that plays a key role in establishing and maintaining polarity in the plane of the epithelium and in the process of convergent extension during gastrulation and neurulation in vertebrates. The Loop-tail (Lp) mouse that develops craniorachischisis carry missense mutations in the PCP core gene Vangl2, that is the mammalian homolog of the Drosophila Strabismus/Van gogh (Stbm/Vang). The presence of mutations in human VANGL1 and VANGL2 genes encourages us to extend the investigation to other PCP genes that, with VANGL, play an essential role in neurulation during development.

  15. Etiology, pathogenesis and prevention of neural tube defects.

    PubMed

    Padmanabhan, Rengasamy

    2006-06-01

    Spina bifida, anencephaly, and encephalocele are commonly grouped together and termed neural tube defects (NTD). Failure of closure of the neural tube during development results in anencephaly or spina bifida aperta but encephaloceles are possibly post-closure defects. NTD are associated with a number of other central nervous system (CNS) and non-neural malformations. Racial, geographic and seasonal variations seem to affect their incidence. Etiology of NTD is unknown. Most of the non-syndromic NTD are of multifactorial origin. Recent in vitro and in vivo studies have highlighted the molecular mechanisms of neurulation in vertebrates but the morphologic development of human neural tube is poorly understood. A multisite closure theory, extrapolated directly from mouse experiments highlighted the clinical relevance of closure mechanisms to human NTD. Animal models, such as circle tail, curly tail, loop tail, shrm and numerous knockouts provide some insight into the mechanisms of NTD. Also available in the literature are a plethora of chemically induced preclosure and a few post-closure models of NTD, which highlight the fact that CNS malformations are of hetergeneitic nature. No Mendelian pattern of inheritance has been reported. Association with single gene defects, enhanced recurrence risk among siblings, and a higher frequency in twins than in singletons indicate the presence of a strong genetic contribution to the etiology of NTD. Non-availability of families with a significant number of NTD cases makes research into genetic causation of NTD difficult. Case reports and epidemiologic studies have implicated a number of chemicals, widely differing therapeutic drugs, environmental contaminants, pollutants, infectious agents, and solvents. Maternal hyperthermia, use of valproate by epileptic women during pregnancy, deficiency and excess of certain nutrients and chronic maternal diseases (e.g. diabetes mellitus) are reported to cause a manifold increase in the

  16. Prevention of congenital defects induced by prenatal alcohol exposure (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sheehan, Megan M.; Karunamuni, Ganga; Pedersen, Cameron J.; Gu, Shi; Doughman, Yong Qiu; Jenkins, Michael W.; Watanabe, Michiko; Rollins, Andrew M.

    2017-02-01

    Over 500,000 women per year in the United States drink during pregnancy, and 1 in 5 of this population also binge drink. Up to 40% of live-born children with prenatal alcohol exposure (PAE) present with congenital heart defects (CHDs) including life-threatening outflow and valvuloseptal anomalies. Previously we established a PAE model in the avian embryo and used optical coherence tomography (OCT) imaging to assay looping-stage (early) cardiac function/structure and septation-stage (late) cardiac defects. Early-stage ethanol-exposed embryos had smaller cardiac cushions (valve precursors) and increased retrograde flow, while late-stage embryos presented with gross head/body defects, and exhibited smaller atrio-ventricular (AV) valves, interventricular septae, and aortic vessels. However, supplementation with the methyl donor betaine reduced gross defects, prevented cardiac defects such as ventricular septal defects and abnormal AV valves, and normalized cardiac parameters. Immunofluorescent staining for 5-methylcytosine in transverse embryo sections also revealed that DNA methylation levels were reduced by ethanol but normalized by co-administration of betaine. Furthermore, supplementation with folate, another methyl donor, in the PAE model appeared to normalize retrograde flow levels which are typically elevated by ethanol exposure. Studies are underway to correlate retrograde flow numbers for folate with associated cushion volumes. Finally, preliminary findings have revealed that glutathione, a key endogenous antioxidant which also regulates methyl group donation, is particularly effective in improving alcohol-impacted survival and gross defect rates. Current investigations will determine whether glutathione has any positive effect on PAE-related CHDs. Our studies could have significant implications for public health, especially related to prenatal nutrition recommendations.

  17. Data Linkage Between the National Birth Defects Prevention Study and the Occupational Information Network (O*NET) to Assess Workplace Physical Activity, Sedentary Behaviors, and Emotional Stressors During Pregnancy

    PubMed Central

    Lee, Laura J.; Symanski, Elaine; Lupo, Philip J.; Tinker, Sarah C.; Razzaghi, Hilda; Pompeii, Lisa A.; Hoyt, Adrienne T.; Canfield, Mark A.; Chan, Wenyaw

    2016-01-01

    Background Knowledge of the prevalence of work-related physical activities, sedentary behaviors, and emotional stressors among pregnant women is limited, and the extent to which these exposures vary by maternal characteristics remains unclear. Methods Data on mothers of 6,817 infants without major birth defects, with estimated delivery during 1997 through 2009 who worked during pregnancy were obtained from the ‘National Birth Defects Prevention Study. Information on multiple domains of occupational exposures was gathered by linking mother’s primary job to the Occupational Information Network Version 9.0. Results The most frequent estimated physical activity associated with jobs during pregnancy was standing. Of 6,337 mothers, 31.0% reported jobs associated with standing for ≥ 75% of their time. There was significant variability in estimated occupational exposures by maternal age, race/ethnicity, and educational level. Conclusions Our findings augment existing literature on occupational physical activities, sedentary behaviors, emotional stressors, and occupational health disparities during pregnancy. PMID:26681357

  18. Inositol for the prevention of neural tube defects: a pilot randomised controlled trial.

    PubMed

    Greene, Nicholas D E; Leung, Kit-Yi; Gay, Victoria; Burren, Katie; Mills, Kevin; Chitty, Lyn S; Copp, Andrew J

    2016-03-28

    Although peri-conceptional folic acid (FA) supplementation can prevent a proportion of neural tube defects (NTD), there is increasing evidence that many NTD are FA non-responsive. The vitamin-like molecule inositol may offer a novel approach to preventing FA-non-responsive NTD. Inositol prevented NTD in a genetic mouse model, and was well tolerated by women in a small study of NTD recurrence. In the present study, we report the Prevention of Neural Tube Defects by Inositol (PONTI) pilot study designed to gain further experience of inositol usage in human pregnancy as a preliminary trial to a future large-scale controlled trial to evaluate efficacy of inositol in NTD prevention. Study subjects were UK women with a previous NTD pregnancy who planned to become pregnant again. Of 117 women who made contact, ninety-nine proved eligible and forty-seven agreed to be randomised (double-blind) to peri-conceptional supplementation with inositol plus FA or placebo plus FA. In total, thirty-three randomised pregnancies produced one NTD recurrence in the placebo plus FA group (n 19) and no recurrences in the inositol plus FA group (n 14). Of fifty-two women who declined randomisation, the peri-conceptional supplementation regimen and outcomes of twenty-two further pregnancies were documented. Two NTD recurred, both in women who took only FA in their next pregnancy. No adverse pregnancy events were associated with inositol supplementation. The findings of the PONTI pilot study encourage a large-scale controlled trial of inositol for NTD prevention, but indicate the need for a careful study design in view of the unwillingness of many high-risk women to be randomised.

  19. Geocoding capacity of birth defects surveillance programs: results from the National Birth Defects Prevention Network Geocoding Survey.

    PubMed

    Wang, Ying; O'Leary, Leslie A; Rickard, Russel S; Mason, Craig A

    2010-01-01

    A Web-based survey focusing on geocoding of birth defects data was developed and administrated to gain an understanding of the capacity of state birth defects programs to geocode maternal residence and to identify barriers to geocoding birth defects data. The survey consisted of 21 questions related to geocoding of maternal residence, type of software used, barriers to geocoding, and data linkage. In August 2007, an e-mail with a Web link to the survey was sent to all state birth defects program contacts in the United States, including the District of Columbia, Puerto Rico, and the Centers for Disease Control and Prevention (CDC) requesting they complete the online survey. By October 2007, 39 (74%) out of 53 birth defects program contacts completed the survey. Although nearly all birth defects programs collect maternal residential data, many are not currently geocoding that data. Results indicated that 97% of the programs that completed the survey reported they collected data on maternal residence, 53% of which reported that the birth defects surveillance data were geocoded to the street address level using maternal residential address at delivery. Twenty six percent of the programs that do not currently geocode the data identified "Software and address reference file are not available" as the most significant barrier to geocoding; another 16% chose "Lack of funding" as the most significant barrier to geocoding. Since geocoding is an important component of spatial analyses used to detect potential clusters of birth defects, leveraging resources to overcome the barriers that prevent programs from geocoding is important.

  20. Mothers' beliefs as to causation and prevention of birth defects in Ile-Ife, Nigeria.

    PubMed

    Ojofeitimi, E O; Elegbe, I

    1984-06-01

    The type of birth defects ever seen or heard of and beliefs as to the causation and means of preventing the defects were investigated among 225 newly deliverd and nursing mothers through interviews. The majority were between the ages of 20 to 29 years; 9.3% were between 35 and 40 years. The bulk of the respondents are illiterates. More than 75% of the mothers had 2 or more children. The most common birth defects seen were amputated leg; dislocated hips; lamed hand or funny elbows or ankles; extra digits; and missing digits. Common perceptions of the causes were God's will (32.9%) and evil doers or evil powers due to witchcraft or sorcery (40.9%). Poor nutrition or poor antenatal care was reported by only 2.2%; while 1.3% attributed the cause to an excessive combination of native and modern drugs. The majority believed that avoidance of walking at night and midafternoon during pregnancy would prevent birth defects. 10.2% and 5.3% were of the opinion that praying to God and going to the herbalist respectively would prevent birth defects. Prevention of birth defects is an essential task for all health workers in Nigeria. The causes of birth defects should be brodcast on radio and television and published in national dialects in the newspapers. 83.6% claimed that they were not informed of various means of preventing birth defects during prenatal clinic visits. The schools should include prevention and causation of birth defects in a health education curriculum.

  1. Inositol, neural tube closure and the prevention of neural tube defects

    PubMed Central

    Leung, Kit‐Yi; Copp, Andrew J.

    2017-01-01

    Susceptibility to neural tube defects (NTDs), such as anencephaly and spina bifida is influenced by genetic and environmental factors including maternal nutrition. Maternal periconceptional supplementation with folic acid significantly reduces the risk of an NTD‐affected pregnancy, but does not prevent all NTDs, and “folic acid non‐responsive” NTDs continue to occur. Similarly, among mouse models of NTDs, some are responsive to folic acid but others are not. Among nutritional factors, inositol deficiency causes cranial NTDs in mice while supplemental inositol prevents spinal and cranial NTDs in the curly tail (Grhl3 hypomorph) mouse, rodent models of hyperglycemia or induced diabetes, and in a folate‐deficiency induced NTD model. NTDs also occur in mice lacking expression of certain inositol kinases. Inositol‐containing phospholipids (phosphoinositides) and soluble inositol phosphates mediate a range of functions, including intracellular signaling, interaction with cytoskeletal proteins, and regulation of membrane identity in trafficking and cell division. Myo‐inositol has been trialed in humans for a range of conditions and appears safe for use in human pregnancy. In pilot studies in Italy and the United Kingdom, women took inositol together with folic acid preconceptionally, after one or more previous NTD‐affected pregnancies. In nonrandomized cohorts and a randomized double‐blind study in the United Kingdom, no recurrent NTDs were observed among 52 pregnancies reported to date. Larger‐scale fully powered trials are needed to determine whether supplementation with inositol and folic acid would more effectively prevent NTDs than folic acid alone. Birth Defects Research 109:68–80, 2017. © 2016 The Authors Birth Defects Research Published by Wiley Periodicals, Inc. PMID:27324558

  2. Puerto Rican primary physicians' knowledge about folic acid supplementation for the prevention of neural tube defects.

    PubMed

    Miranda, Ana; Dávila Torres, René R; Gorrín Peralta, José J; Montes de Longo, Idalina

    2003-12-01

    We conducted a study of a group of primary physicians in Puerto Rico to evaluate their knowledge about folic acid supplementation to prevent neural tube defects. The study design was transverse-correlational. A total of 66 primary physicians in two hospitals (public and private) participated in the study. The sample was nonrandom and opportunistic, and only those physicians present in the hospitals at the moment of distribution of the questionnaires participated. A self-administered and anonymous questionnaire was used. Descriptive statistics and cross-tabular analysis were used to describe the results of this study. Inferential statistics were also used, including Chi square and t-tests to establish the associations/differences between physician knowledge and the independent variables. Of the participants, 87.9% demonstrated an inadequate knowledge about folic acid supplementation for the prevention of neural tube defects as part of preconception care and only 12.1% demonstrated adequate knowledge. Older physicians had greater knowledge about folic acid. Also, women demonstrated greater knowledge about folic acid than did men. Most of the physicians who always recommend supplementation to their patients demonstrated a greater knowledge about folic acid, and all participants with adequate knowledge came from the public hospital. Despite a concerted effort by the Health Department of Puerto Rico to provide education in the importance of folic acid supplementation to reduce the incidence of neural tube defects, primary physicians in two Puerto Rican hospitals generally have not availed themselves of this training and showed a lack of knowledge on this important clinical issue. Copyright 2003 Wiley-Liss, Inc.

  3. Etiology and clinical presentation of birth defects: population based study

    PubMed Central

    Carey, John C; Byrne, Janice L B; Krikov, Sergey; Botto, Lorenzo D

    2017-01-01

    Objective To assess causation and clinical presentation of major birth defects. Design Population based case cohort. Setting Cases of birth defects in children born 2005-09 to resident women, ascertained through Utah’s population based surveillance system. All records underwent clinical re-review. Participants 5504 cases among 270 878 births (prevalence 2.03%), excluding mild isolated conditions (such as muscular ventricular septal defects, distal hypospadias). Main outcome measures The primary outcomes were the proportion of birth defects with a known etiology (chromosomal, genetic, human teratogen, twinning) or unknown etiology, by morphology (isolated, multiple, minors only), and by pathogenesis (sequence, developmental field defect, or known pattern of birth defects). Results Definite cause was assigned in 20.2% (n=1114) of cases: chromosomal or genetic conditions accounted for 94.4% (n=1052), teratogens for 4.1% (n=46, mostly poorly controlled pregestational diabetes), and twinning for 1.4% (n=16, conjoined or acardiac). The 79.8% (n=4390) remaining were classified as unknown etiology; of these 88.2% (n=3874) were isolated birth defects. Family history (similarly affected first degree relative) was documented in 4.8% (n=266). In this cohort, 92.1% (5067/5504) were live born infants (isolated and non-isolated birth defects): 75.3% (4147/5504) were classified as having an isolated birth defect (unknown or known etiology). Conclusions These findings underscore the gaps in our knowledge regarding the causes of birth defects. For the causes that are known, such as smoking or diabetes, assigning causation in individual cases remains challenging. Nevertheless, the ongoing impact of these exposures on fetal development highlights the urgency and benefits of population based preventive interventions. For the causes that are still unknown, better strategies are needed. These can include greater integration of the key elements of etiology, morphology, and

  4. Complex cardiac defects after ethanol exposure during discrete cardiogenic events in zebrafish: Prevention with folic acid

    PubMed Central

    Sarmah, Swapnalee; Marrs, James A.

    2014-01-01

    BACKGROUND Fetal alcohol spectrum disorder (FASD) describes a range of birth defects including various congenital heart defects (CHDs). Mechanisms of FASD-associated CHDs are not understood. Whether alcohol interferes with a single critical event or with multiple events in heart formation is not known. RESULTS Our zebrafish embryo experiments showed that ethanol interrupts different cardiac regulatory networks and perturbed multiple steps of cardiogenesis (specification, myocardial migration, looping, chamber morphogenesis and endocardial cushion formation). Ethanol exposure during gastrulation until cardiac specification or during myocardial midline migration did not produce severe or persistent heart development defects. However, exposure comprising gastrulation until myocardial precursor midline fusion or during heart patterning stages produced aberrant heart looping and defective endocardial cushions. Continuous exposure during entire cardiogenesis produced complex cardiac defects leading to severely defective myocardium, endocardium, and endocardial cushions. Supplementation of retinoic acid with ethanol partially rescued early heart developmental defects, but the endocardial cushions did not form correctly. In contrast, supplementation of folic acid rescued normal heart development, including the endocardial cushions. CONCLUSIONS Our results indicate that ethanol exposure interrupted divergent cardiac morphogenesis events causing heart defects. Folic acid supplementation was effective in preventing a wide spectrum of ethanol-induced heart developmental defects. PMID:23832875

  5. Economic burden of neural tube defects and impact of prevention with folic acid: a literature review.

    PubMed

    Yi, Yunni; Lindemann, Marion; Colligs, Antje; Snowball, Claire

    2011-11-01

    Neural tube defects (NTDs) are the second most common group of serious birth defects. Although folic acid has been shown to reduce effectively the risk of NTDs and measures have been taken to increase the awareness, knowledge, and consumption of folic acid, the full potential of folic acid to reduce the risk of NTDs has not been realized in most countries. To understand the economic burden of NTDs and the economic impact of preventing NTDs with folic acid, a systematic review was performed on relevant studies. A total of 14 cost of illness studies and 10 economic evaluations on prevention of NTDs with folic acid were identified. Consistent findings were reported across all of the cost of illness studies. The lifetime direct medical cost for patients with NTDs is significant, with the majority of cost being for inpatient care, for treatment at initial diagnosis in childhood, and for comorbidities in adult life. The lifetime indirect cost for patients with spina bifida is even greater due to increased morbidity and premature mortality. Caregiver time costs are also significant. The results from the economic evaluations demonstrate that folic acid fortification in food and preconception folic acid consumption are cost-effective ways to reduce the incidence and prevalence of NTDs. This review highlights the significant cost burden that NTDs pose to healthcare systems, various healthcare payers, and society and concludes that the benefits of prevention of NTDs with folic acid far outweigh the cost. Further intervention with folic acid is justified in countries where the full potential of folic acid to reduce the risk of NTDs has not been realized.

  6. Prevention of neural tube defects in the UK: a missed opportunity

    PubMed Central

    Morris, JK; Rankin, J; Draper, ES; Kurinczuk, JJ; Springett, A; Tucker, D; Wellesley, D; Wreyford, B; Wald, NJ

    2016-01-01

    Objective In 1991, the Medical Research Council (MRC) Vitamin Study demonstrated that folic acid taken before pregnancy and in early pregnancy reduced the risk of a neural tube defect (NTD). We aimed to estimate the number of NTD pregnancies that would have been prevented if flour had been fortified with folic acid in the UK from 1998 as it had been in the USA. Design Estimates of NTD prevalence, the preventive effect of folic acid and the proportion of women taking folic acid supplements before pregnancy were used to predict the number of NTD pregnancies that would have been prevented if folic acid fortification had been implemented. Setting Eight congenital anomaly registers in England and Wales. Main outcome measures The prevalence of pregnancies with an NTD in the UK and the number of these pregnancies that would have been prevented if folic acid fortification had been implemented. Results From 1991 to 2012, the prevalence of NTD pregnancies was 1.28 (95% CI 1.24 to 1.31) per 1000 total births (19% live births, 81% terminations and 0.5% stillbirths and fetal deaths ≥20 weeks’ gestation). If the USA levels of folic acid fortification from 1998 onwards had been adopted in the UK, an estimated 2014 fewer NTD pregnancies would have occurred. Conclusions Failure to implement folic acid fortification in the UK has caused, and continues to cause, avoidable terminations of pregnancy, stillbirths, neonatal deaths and permanent serious disability in surviving children. PMID:26681697

  7. Nucleotide precursors prevent folic acid-resistant neural tube defects in the mouse.

    PubMed

    Leung, Kit-Yi; De Castro, Sandra C P; Savery, Dawn; Copp, Andrew J; Greene, Nicholas D E

    2013-09-01

    Closure of the neural tube during embryogenesis is a crucial step in development of the central nervous system. Failure of this process results in neural tube defects, including spina bifida and anencephaly, which are among the most common birth defects worldwide. Maternal use of folic acid supplements reduces risk of neural tube defects but a proportion of cases are not preventable. Folic acid is thought to act through folate one-carbon metabolism, which transfers one-carbon units for methylation reactions and nucleotide biosynthesis. Hence suboptimal performance of the intervening reactions could limit the efficacy of folic acid. We hypothesized that direct supplementation with nucleotides, downstream of folate metabolism, has the potential to support neural tube closure. Therefore, in a mouse model that exhibits folic acid-resistant neural tube defects, we tested the effect of specific combinations of pyrimidine and purine nucleotide precursors and observed a significant protective effect. Labelling in whole embryo culture showed that nucleotides are taken up by the neurulating embryo and incorporated into genomic DNA. Furthermore, the mitotic index was elevated in neural folds and hindgut of treated embryos, consistent with a proposed mechanism of neural tube defect prevention through stimulation of cellular proliferation. These findings may provide an impetus for future investigations of supplemental nucleotides as a means to prevent a greater proportion of human neural tube defects than can be achieved by folic acid alone.

  8. [Neural tube defects and folic acid: a historical overview of a highly successful preventive intervention].

    PubMed

    Vásquez, Adriana Ordoñez; Suarez-Obando, Fernando

    2015-12-01

    This article gives a broad overview of part of the historical evolution of medical knowledge about neural tube defects (NTD) and the discovery of vitamin B9 or folic acid, as well as some relevant research events that, over the course of several centuries, defined the relationships between the understanding of central nervous system embryology, the discovery of the vitamin, the correlation between folic acid and cell proliferation and lastly the development of preventive measures for this type of defects. This narrative allows us to examine historically relevant concepts underlying clinical actions with a populational impact that prevent NTDs via folic acid consumption prior to conception.

  9. [Folic acid and prevention of neural tube closure defects: the question is not solved yet].

    PubMed

    Vidailhet, M; Bocquet, A; Bresson, J-L; Briend, A; Chouraqui, J-P; Dupont, C; Darmaun, D; Frelut, M-L; Ghisolfi, J; Girardet, J-P; Goulet, O; Putet, G; Rieu, D; Rigo, J; Turck, D

    2008-07-01

    Between 1981 and 1996, several interventional studies proved the efficacy of periconceptional folic acid supplementation in the prevention of neural tube closure defects (NTCD), first in women at risk (with a previous case of NTCD) and also in women of the general population in age to become pregnant. The poor observance of this supplementation led several countries (USA, Canada, Chile...) to decide mandatory folic acid fortification of cereals, which permitted a 30% (USA) to 46% (Canada) reduction in the incidence of NTCD. Moreover, this benefit was accompanied by a diminished incidence of several other malformations and of stroke and coronary accidents in elderly people. However, several papers drew attention to an increased risk of colorectal and breast cancer in relation with high blood folate levels and the use of folic acid supplements. A controlled interventional study showed a higher rate of recurrence of colic adenomas and a higher percentage of advanced adenomas in subjects receiving 1mg/day of folic acid. A recent study demonstrated an abrupt reversal of the downward trend in colorectal cancer 1 year after the beginning of cereal folic acid fortification in the USA and Canada. Two studies also reported impaired cognitive functions in elder persons with defective vitamin B(12) status. Taken in aggregate, these studies question the wisdom of a nationwide, mandatory, folic acid fortification of cereals. As of today, despite their limited preventive efficacy, a safe approach is to keep our current French recommendations and to increase the awareness of all caregivers, so as to improve the observance of these recommendations.

  10. Prevention of late blowing defect by reuterin produced in cheese by a Lactobacillus reuteri adjunct.

    PubMed

    Gómez-Torres, Natalia; Ávila, Marta; Gaya, Pilar; Garde, Sonia

    2014-09-01

    In this study, reuterin-producing Lactobacillus reuteri INIA P572 was added to cheese as an adjunct culture together with 50 or 100 mM glycerol (required for reuterin production), with the aim of controlling Clostridium tyrobutyricum CECT 4011 growth and preventing the late blowing defect (LBD) of cheese caused by this strain. L. reuteri survived cheese manufacture and produced reuterin in situ, detected at 6 and 24 h. However, the produced reuterin was enough to inhibit the growth of Clostridium, showing undetectable spore counts from day 30 onward and, therefore, to prevent cheese LBD during ripening (60 d, 14 °C). The acidification of these cheeses was not affected, although from day 14 they showed significantly lower lactococci counts than cheese made only with the starter (control cheese). Cheeses with LBD showed lower levels of lactic acid than control cheese and the formation of propionic and butyric acids, but cheeses with reuterin showed the same organic acids profile than control cheese. The cheese made with L. reuteri and 100 mM glycerol showed a light pink colour, not observed in the cheese made with L. reuteri and 50 mM glycerol. These results demonstrated a potent anti-clostridial activity of reuterin produced in an actual food product like cheese, and proved to be a novel approach to prevent LBD of cheese.

  11. Assessment of Turkish women's knowledge concerning folic acid and prevention of birth defects.

    PubMed

    Unusan, Nurhan

    2004-10-01

    In Turkey, the incidence of neural tube defects (NTDs) is 30.1 per 10,000 births. For this reason it seems an important problem for women of childbearing age. Adequate periconceptional consumption of folic acid could prevent NTDs. Most women are unaware of this recommendation. The objectives of this study were to evaluate women' knowledge and beliefs with regard to folic acid, and to estimate the consumption frequency of vitamin supplements periconceptionally and during the first trimester of pregnancy. Eight hundred and eighteen married women who had delivered a live-born infant within the previous 12 months completed the questionnaire. Each subject participated in a 20-minute interview, with the questionnaire comprising multiple-choice statements. A random sample of 10 public health centres was drawn from 27 in three districts in Konya where about 50% of the population lives. Only 22% of subjects had heard or read about folic acid. Thirteen per cent of women indicated knowledge of the direct link between folic acid supplementation and NTD prevention. The knowledge was greatest among 26- to 35-year-olds. Women with a university degree were more likely to have heard about folic acid than were less-educated women. The results indicate that further government efforts are needed to inform the population and promote the optimal use of folic acid supplements and folate-enriched foods. It is the responsibility of national authorities to increase health education concerning folic acid and the prevention of NTDs in their countries.

  12. Folate and Prevention of Neural Tube Defects: New Insights from a Bayesian Model.

    PubMed

    Ströhle, Alexander; Bohn, Torsten

    2015-01-01

    Maternal folate status before and during pregnancy influences a woman's risk of having a pregnancy affected by congenital malformations of the neural tube (neural tube defects, NTD). For NTD prevention, it is recommended that women use periconceptional supplementation of folic acid. However, the recommended dose varies considerably (400 - 800 µg folic acid/day). Insufficient data exists on the relation between folate status and the risk of NTD. A recent study published in the British Medical Journal provides evidence for a generalizable dose-response relation between folate status and risk of NTD. The lowest risk of having a child with NTD was related to red blood cell (RBC) folate concentrations of ≥ 1000 nmol/L.

  13. Studying post-etching silicon crystal defects on 300mm wafer by automatic defect review AFM

    NASA Astrophysics Data System (ADS)

    Zandiatashbar, Ardavan; Taylor, Patrick A.; Kim, Byong; Yoo, Young-kook; Lee, Keibock; Jo, Ahjin; Lee, Ju Suk; Cho, Sang-Joon; Park, Sang-il

    2016-03-01

    Single crystal silicon wafers are the fundamental elements of semiconductor manufacturing industry. The wafers produced by Czochralski (CZ) process are very high quality single crystalline materials with known defects that are formed during the crystal growth or modified by further processing. While defects can be unfavorable for yield for some manufactured electrical devices, a group of defects like oxide precipitates can have both positive and negative impacts on the final device. The spatial distribution of these defects may be found by scattering techniques. However, due to limitations of scattering (i.e. light wavelength), many crystal defects are either poorly classified or not detected. Therefore a high throughput and accurate characterization of their shape and dimension is essential for reviewing the defects and proper classification. While scanning electron microscopy (SEM) can provide high resolution twodimensional images, atomic force microscopy (AFM) is essential for obtaining three-dimensional information of the defects of interest (DOI) as it is known to provide the highest vertical resolution among all techniques [1]. However AFM's low throughput, limited tip life, and laborious efforts for locating the DOI have been the limitations of this technique for defect review for 300 mm wafers. To address these limitations of AFM, automatic defect review AFM has been introduced recently [2], and is utilized in this work for studying DOI on 300 mm silicon wafer. In this work, we carefully etched a 300 mm silicon wafer with a gaseous acid in a reducing atmosphere at a temperature and for a sufficient duration to decorate and grow the crystal defects to a size capable of being detected as light scattering defects [3]. The etched defects form a shallow structure and their distribution and relative size are inspected by laser light scattering (LLS). However, several groups of defects couldn't be properly sized by the LLS due to the very shallow depth and low

  14. Risk reduction using DDP (Defect Detection and Prevention): Software support and software applications

    NASA Technical Reports Server (NTRS)

    Feather, M. S.

    2001-01-01

    Risk assessment and mitigation is the focus of the Defect Detection and Prevention (DDP) process, which has been applied to spacecraft technology assessments and planning, both hardware and software. DDP's major elements and their relevance to core requirement engineering concerns are summarized. The accompanying research demonstration illustrates DDP's tool support, and further customizations for application to software.

  15. Topological Defects in Liquid Crystals: Studying the Correlation between Defects and Curvature

    NASA Astrophysics Data System (ADS)

    Melton, Charles

    2015-03-01

    Topological defects have recently been the subject of many fascinating studies in soft condensed matter physics. In particular, linking the evolution of topological defects to curvature changes has been a focus, leading possible applications in the areas such as cosmetics, pharmaceuticals, and electronics. In this study, defects in nematic liquid crystal droplets are investigated via laboratory and theoretical techniques. Nematic liquid crystal defects are reproduced via Monte Carlo simulations using a modified 2D XY-Model Hamiltonian. The simulation is performed on a curved surface to replicate a nematic droplet and examine possible defect configurations. To complement this theoretical work, we have trapped nematic droplets inside a dual-beam optical trap. This system allows controllable non-contact droplet deformation on a microscope based platform. Future work will focus on using the trap to stretch nematic droplets, correlating the changing topological defects with theoretical predictions.

  16. Folic acid for the prevention of neural tube defects: U.S. Preventive Services Task Force recommendation statement.

    PubMed

    2009-05-05

    In 1996, the U.S. Preventive Services Task Force (USPSTF) recommended that all women planning or capable of pregnancy take a multivitamin supplement containing folic acid for the prevention of neural tube defects. This recommendation is an update of the 1996 USPSTF recommendation. The USPSTF reviewed the evidence on folic acid supplementation in women of childbearing age published since the 1996 USPSTF recommendation. The USPSTF did not review the evidence on folic acid food fortification, counseling to increase dietary intake, or screening for neural tube defects. The USPSTF recommends that all women planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400 to 800 microg) of folic acid. (Grade A recommendation).

  17. Prevention of neural tube defects in Lrp2 mutant mouse embryos by folic acid supplementation.

    PubMed

    Sabatino, Julia A; Stokes, Bethany A; Zohn, Irene E

    2017-01-20

    Neural tube defects (NTDs) are among the most common structural birth defects in humans and are caused by the complex interaction of genetic and environmental factors. Periconceptional supplementation with folic acid can prevent NTDs in both mouse models and human populations. A better understanding of how genes and environmental factors interact is critical toward development of rational strategies to prevent NTDs. Low density lipoprotein-related protein 2 (Lrp2) is involved in endocytosis of the folic acid receptor among numerous other nutrients and ligands. We determined the effect of iron and/or folic acid supplementation on the penetrance of NTDs in the Lrp2(null) mouse model. The effects of supplementation on folate and iron status were measured in embryos and dams. Periconceptional dietary supplementation with folic acid did not prevent NTDs in Lrp2 mutant embryos, whereas high levels of folic acid supplementation by intraperitoneal injection reduced incidence of NTDs. Importantly, Lrp2(null/+) dams had reduced blood folate levels that improved with daily intraperitoneal injections of folate but not dietary supplementation. On the contrary, iron supplementation had no effect on the penetrance of NTDs in Lrp2 mutant embryos and negated the preventative effect of folic acid supplementation in Lrp2(null/null) mutants. Lrp2 is required for folate homeostasis in heterozygous dams and high levels of supplementation prevents NTDs. Furthermore, high levels of dietary iron supplementation interfered with folic acid supplementation negating the positive effects of supplementation in this model. Birth Defects Research 109:16-26, 2017. © 2016 The Authors Birth Defects Published by Wiley Periodicals, Inc. © 2016 The Authors Birth Defects Research Published by Wiley Periodicals, Inc.

  18. Prevention of neural tube defects in the UK: a missed opportunity.

    PubMed

    Morris, J K; Rankin, J; Draper, E S; Kurinczuk, J J; Springett, A; Tucker, D; Wellesley, D; Wreyford, B; Wald, N J

    2016-07-01

    In 1991, the Medical Research Council (MRC) Vitamin Study demonstrated that folic acid taken before pregnancy and in early pregnancy reduced the risk of a neural tube defect (NTD). We aimed to estimate the number of NTD pregnancies that would have been prevented if flour had been fortified with folic acid in the UK from 1998 as it had been in the USA. Estimates of NTD prevalence, the preventive effect of folic acid and the proportion of women taking folic acid supplements before pregnancy were used to predict the number of NTD pregnancies that would have been prevented if folic acid fortification had been implemented. Eight congenital anomaly registers in England and Wales. The prevalence of pregnancies with an NTD in the UK and the number of these pregnancies that would have been prevented if folic acid fortification had been implemented. From 1991 to 2012, the prevalence of NTD pregnancies was 1.28 (95% CI 1.24 to 1.31) per 1000 total births (19% live births, 81% terminations and 0.5% stillbirths and fetal deaths ≥20 weeks' gestation). If the USA levels of folic acid fortification from 1998 onwards had been adopted in the UK, an estimated 2014 fewer NTD pregnancies would have occurred. Failure to implement folic acid fortification in the UK has caused, and continues to cause, avoidable terminations of pregnancy, stillbirths, neonatal deaths and permanent serious disability in surviving children. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  19. Folic Acid Supplementation for the Prevention of Neural Tube Defects: US Preventive Services Task Force Recommendation Statement.

    PubMed

    Bibbins-Domingo, Kirsten; Grossman, David C; Curry, Susan J; Davidson, Karina W; Epling, John W; García, Francisco A R; Kemper, Alex R; Krist, Alex H; Kurth, Ann E; Landefeld, C Seth; Mangione, Carol M; Phillips, William R; Phipps, Maureen G; Pignone, Michael P; Silverstein, Michael; Tseng, Chien-Wen

    2017-01-10

    Neural tube defects are among the most common major congenital anomalies in the United States and may lead to a range of disabilities or death. Daily folic acid supplementation in the periconceptional period can prevent neural tube defects. However, most women do not receive the recommended daily intake of folate from diet alone. To update the 2009 US Preventive Services Task Force (USPSTF) recommendation on folic acid supplementation in women of childbearing age. In 2009, the USPSTF reviewed the effectiveness of folic acid supplementation in women of childbearing age for the prevention of neural tube defects in infants. The current review assessed new evidence on the benefits and harms of folic acid supplementation. The USPSTF assessed the balance of the benefits and harms of folic acid supplementation in women of childbearing age and determined that the net benefit is substantial. Evidence is adequate that the harms to the mother or infant from folic acid supplementation taken at the usual doses are no greater than small. Therefore, the USPSTF reaffirms its 2009 recommendation. The USPSTF recommends that all women who are planning or capable of pregnancy take a daily supplement containing 0.4 to 0.8 mg (400-800 µg) of folic acid. (A recommendation).

  20. The Left Shifted Oxyhemoglobin Curve in Sepsis: A Preventable Defect

    PubMed Central

    Watkins, George M.; Rabelo, Alvaro; Plzak, Louis F.; Sheldon, George F.

    1974-01-01

    Nine patients with severe sepsis were studied to determine causes for any alterations in oxygen dissociation. Seven of the patients had oxyhemoglobin curves shifted to the left of expected and diminished DPG levels. These deficiences were not corrected in one case. The other eight patients survived or expired with normal to elevated P50T and DPG levels. In this study, three factors occurring either individually, in concordance, or in sequence were present when P50T was decreased. Correction of these deficiencies lead to normalization and, in one case, exceedingly high P50T and DPG levels. Where hypophosphatemia, acidosis, and transfusion of DPG deficient blood were avoided, no such change occurred. Hypophosphatemia is a common occurrence in the seriously ill patient whether or not hyperalimentation is used and may occur in spite of phosphate supplementation. Blood transfusions with CPD as the preservative are effective in reducing the severity of this disorder by the addition of an inorganic phosphate load. Septic shock itself had no untoward effect on oxygen dissociation. This held true even in the terminal stages of the disease process. PMID:4842983

  1. Fetal alcohol syndrome: cardiac birth defects in mice and prevention with folate.

    PubMed

    Serrano, Maria; Han, Mingda; Brinez, Pilar; Linask, Kersti K

    2010-07-01

    Alcohol (ethanol) consumption during pregnancy is linked to congenital heart defects that are associated with fetal alcohol syndrome. Recent reports have associated ethanol exposure with the Wnt/beta-catenin pathway. Therefore, we defined whether ethanol affects Wnt/beta-catenin signaling during cardiac cell specification. Pregnant mice on embryonic day 6.75 during gastrulation were exposed by an intraperitoneal injection to a binge-drinking dose of ethanol. Folic acid supplementation of mouse diet was tested for the prevention of ethanol-induced cardiac birth defects. Acute ethanol exposure induced myocardial wall changes and atrioventricular and semilunar valve defects, which was determined by echocardiography on embryonic day 15.5. A high folate diet prevented the ethanol-induced cardiac defects. Ethanol exposure in avian embryos suppressed 2 key Wnt-modulated genes that are involved in cardiac induction; folic acid rescued normal gene expression. Folic acid supplementation alone or with myoinositol prevented alcohol potentiation of Wnt/beta-catenin signaling that allowed normal gene activation and cardiogenesis. Copyright (c) 2010 Mosby, Inc. All rights reserved.

  2. The continuing challenge of understanding, preventing, and treating neural tube defects.

    PubMed

    Wallingford, John B; Niswander, Lee A; Shaw, Gary M; Finnell, Richard H

    2013-03-01

    Human birth defects are a major public health burden: The Center for Disease Control estimates that 1 of every 33 United States newborns presents with a birth defect, and worldwide the estimate approaches 6% of all births. Among the most common and debilitating of human birth defects are those affecting the formation of the neural tube, the precursor to the central nervous system. Neural tube defects (NTDs) arise from a complex combination of genetic and environmental interactions. Although substantial advances have been made in the prevention and treatment of these malformations, NTDs remain a substantial public health problem, and we are only now beginning to understand their etiology. Here, we review the process of neural tube development and how defects in this process lead to NTDs, both in humans and in the animal models that serve to inform our understanding of these processes. The insights we are gaining will help generate new intervention strategies to tackle the clinical challenges and to alleviate the personal and societal burdens that accompany these defects.

  3. [Neural tube defects in Austria: Assumption and calculations on the prevention potential through folic acid enrichment and supplementation].

    PubMed

    Schiller-Frühwirth, I; Mittermayr, T; Wild, C

    2010-12-01

    Countries with obligatory fortification of food (USA, Canada) document a significant decrease of neural tube defects in newborns. In this study the Daly or, respectively, the Wald method was employed for calculating the potential of fortification/and supplementation for prevention in Austria. According to the EUROCAT study, in Austria the overall prevalence of neural tube defects (live birth, still births and induced abortions due to neural defect) is assumed to be 7.95 per 10,000 live and still births, and the prevalence of 3.9 per 10,000 live births - that is 62 or, respectively, 30 in absolute numbers per 78,000 births per year. In 2006, 26 live-born children with neural tube defects were actually reported in Austria by Statistik Austria. Different folic acid fortification and supplementation strategies can avoid 1.2-1.4 per 10,000 (9-11 cases) of neural tube defects (live and still births). Folic acid supplements are effective to decrease the amount of neural tube defects, however, only when pregnancies are planned. Thus, evidence-based neural tube defects are more common among lower social groups. An obligatory fortification of food could therefore reach unplanned pregnancies and women facing social problems. A reason to justify this population-based intervention where people need not decide for themselves could be the reduction of social imbalances. There are, of course, advantages and disadvantages of obligatory fortification of food and, therefore, all circumstances have to be taken into consideration. © Georg Thieme Verlag KG Stuttgart · New York.

  4. Folic acid supplement use in the prevention of neural tube defects.

    PubMed

    Delany, C; McDonnell, R; Robson, M; Corcoran, S; Fitzpatrick, C; De La Harpe, D

    2011-01-01

    In 2008, planned folic acid fortification for the prevention of Neural Tube Defects (NTD) was postponed. Concurrently, the economic recession may have affected dietary folic acid intake, placing increased emphasis on supplement use. This study examined folic acid supplement use in 2009. A cross-sectional survey of 300 ante-natal women was undertaken to assess folic acid knowledge and use. Associations between demographic, obstetric variables and folic acid knowledge and use were examined. A majority, 284/297 (96%), had heard of folic acid, and 178/297 (60%) knew that it could prevent NTD. Most, 270/297 (91%) had taken it during their pregnancy, but only 107/297 (36%) had used it periconceptionally. Being older, married, planned pregnancy and better socioeconomic status were associated with periconceptional use. Periconceptional folic acid use in 2009 was very low, little changed from economic status were associated with periconceptional use. Periconceptional folic acid use in 2009 was very low, little changed from earlier years. Continuous promotion efforts are necessary. Close monitoring of folic acid intake and NTD rates is essential, particularly in the absence of fortification.

  5. Management of mandibular third molar extraction sites to prevent periodontal defects.

    PubMed

    Dodson, Thomas B

    2004-10-01

    Persistent periodontal defects on the distal aspect of the mandibular second molar (M2) is a reported complication of mandibular third molar (M3) extraction. The purpose of this study was to measure the efficacy of demineralized bone powder (DBP) or guided-tissue regeneration therapy (GTR therapy) in preventing periodontal defects on the distal aspect of the M2 following M3 extraction. We implemented a single-blind, randomized, controlled clinical trial composed of a sample of subjects > or = 26 years of age who required extraction of bilateral M3s. The primary predictor variable was treatment group. Each subject was randomly assigned to receive either DBP or GTR therapy. Within subjects, 1 M3 site was randomly selected to be the experimental site and the opposite M3 served as a control and was permitted to heal without intervention. The primary outcome variable was the change in attachment levels (AL) and probing depths (PD) on the disto-buccal aspect of M2 between T 0 (immediate preoperatively) and T 4 (26 weeks postoperatively). Appropriate sample size estimates, descriptive, bivariate, and multivariate statistics were computed. Twelve subjects in the DBP group and 12 subjects in the GTR-therapy group completed the study. For both treatment and control sites, between T 0 and T 4, there were statistically significant improvements in AL (> or = 2.2 mm; P <.001) and PD (> or = 2.6 mm; P <.001). Within-subjects comparisons showed no significant differences in AL or PD between treatment and control M3 sites ( P > or =.3) at T 0 or T 4. The results of this study suggest that attachment levels and probing depths improve after M3 removal. In this sample, DBP or GTR therapy did not offer predictable benefit over no treatment.

  6. How surface reparation prevents catalytic oxidation of carbon monoxide on atomic gold at defective magnesium oxide surfaces.

    PubMed

    Töpfer, Kai; Tremblay, Jean Christophe

    2016-07-21

    In this contribution, we study using first principles the co-adsorption and catalytic behaviors of CO and O2 on a single gold atom deposited at defective magnesium oxide surfaces. Using cluster models and point charge embedding within a density functional theory framework, we simulate the CO oxidation reaction for Au1 on differently charged oxygen vacancies of MgO(001) to rationalize its experimentally observed lack of catalytic activity. Our results show that: (1) co-adsorption is weakly supported at F(0) and F(2+) defects but not at F(1+) sites, (2) electron redistribution from the F(0) vacancy via the Au1 cluster to the adsorbed molecular oxygen weakens the O2 bond, as required for a sustainable catalytic cycle, (3) a metastable carbonate intermediate can form on defects of the F(0) type, (4) only a small activation barrier exists for the highly favorable dissociation of CO2 from F(0), and (5) the moderate adsorption energy of the gold atom on the F(0) defect cannot prevent insertion of molecular oxygen inside the defect. Due to the lack of protection of the color centers, the surface becomes invariably repaired by the surrounding oxygen and the catalytic cycle is irreversibly broken in the first oxidation step.

  7. Defectivity reduction studies for ArF immersion lithography

    NASA Astrophysics Data System (ADS)

    Matsunaga, Kentaro; Kondoh, Takehiro; Kato, Hirokazu; Kobayashi, Yuuji; Hayasaki, Kei; Ito, Shinichi; Yoshida, Akira; Shimura, Satoru; Kawasaki, Tetsu; Kyoda, Hideharu

    2007-03-01

    Immersion lithography is widely expected to meet the manufacturing requirements of future device nodes. A critical development in immersion lithography has been the construction of a defect-free process. Two years ago, the authors evaluated the impact of water droplets made experimentally on exposed resist films and /or topcoat. (1) The results showed that the marks of drying water droplet called watermarks became pattern defects with T-top profile. In the case that water droplets were removed by drying them, formation of the defects was prevented. Post-exposure rinse process to remove water droplets also prevented formation of the defects. In the present work, the authors evaluated the effect of pre- and post-exposure rinse processes on hp 55nm line and space pattern with Spin Rinse Process Station (SRS) and Post Immersion Rinse Process Station (PIR) modules on an inline lithography cluster with the Tokyo Electron Ltd. CLEAN TRACK TM LITHIUS TM i+ and ASML TWINSCAN XT:1700Fi , 193nm immersion scanner. It was found that total defectivity is decreased by pre- and post-exposure rinse. In particular, bridge defects and large bridge defects were decreased by pre- and post-exposure rinse. Pre- and post-exposure rinse processes are very effective to reduce the bridge and large bridge defects of immersion lithography.

  8. Defect stability in thorium monocarbide: An ab initio study

    NASA Astrophysics Data System (ADS)

    Wang, Chang-Ying; Han, Han; Shao, Kuan; Cheng, Cheng; Huai, Ping

    2015-09-01

    The elastic properties and point defects of thorium monocarbide (ThC) have been studied by means of density functional theory based on the projector-augmented-wave method. The calculated electronic and elastic properties of ThC are in good agreement with experimental data and previous theoretical results. Five types of point defects have been considered in our study, including the vacancy defect, interstitial defect, antisite defect, schottky defect, and composition-conserving defect. Among these defects, the carbon vacancy defect has the lowest formation energy of 0.29 eV. The second most stable defect (0.49 eV) is one of composition-conserving defects in which one carbon is removed to another carbon site forming a C2 dimer. In addition, we also discuss several kinds of carbon interstitial defects, and predict that the carbon trimer configuration may be a transition state for a carbon dimer diffusion in ThC. Project supported by the International S&T Cooperation Program of China (Grant No. 2014DFG60230), the National Natural Science Foundation of China (Grant No. 91326105), the National Basic Research Program of China (Grant No. 2010CB934504), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA02040104).

  9. Inositol prevents folate-resistant neural tube defects in the mouse.

    PubMed

    Greene, N D; Copp, A J

    1997-01-01

    Clinical trials demonstrate that up to 70% of neural tube defects (NTDs) can be prevented by folic acid supplementation in early pregnancy, whereas the remaining NTDs are resistant to folate. Here, we show that a second vitamin, myo-inositol, is capable of significantly reducing the incidence of spinal NTDs in curly tail mice, a genetic model of folate-resistant NTDs. Inositol increases flux through the inositol/lipid cycle, stimulating protein kinase C activity and upregulating expression of retinoic acid receptor beta, specifically in the caudal portion of the embryonic hindgut. This reduces the delay in closure of the posterior neuropore, the embryonic defect that is known to lead directly to spina bifida in curly tail embryos. Our findings reveal a molecular pathway of NTD prevention and suggest the possible efficacy of combined treatment with folate and inositol in overcoming the majority of human NTDs.

  10. Application of data screening to drug exposure in large risk factor studies of birth defects.

    PubMed

    Louik, Carol; Werler, Martha; Anderka, Marlene; Mitchell, Allen A

    2015-08-01

    Birth defects are the leading cause of infant death. While causes of most are unknown, those that might be due to medication use are among the most preventable. This study describes an approach to identifying those medications that most warrant attention by using a "screen" program that calculates odds ratios for pairs of exposures and specific birth defects. We discuss the development of this tool and illustrate its application to two large risk factor studies, the Slone Epidemiology Center's Birth Defects Study and the Centers for Disease Control and Prevention's National Birth Defects Prevention Study, ideal settings for the systematic study of risks and relative safety of drugs in relation to birth defects while recognizing the inherent limitations of such an approach. Suggestions for establishing criteria for exposures and outcomes that balance the need for specific details with the practical considerations of sample size and volume of output are presented. Selection of appropriate exposure reference categories and control groups is also discussed, as well as the need to address potential confounding. An example that motivated a detailed investigation of possible associations between a medication (butalbital) and selected specific birth defects is provided. While screening programs such as the one described can be a valuable tool for exploring potential associations in large data bases, they must be applied with caution. The issue of multiple testing and chance findings is a major concern. While statistics are a necessary component, human judgment must be an integral part of the process. © 2015 Wiley Periodicals, Inc.

  11. CDC Grand Rounds: Understanding the Causes of Major Birth Defects - Steps to Prevention.

    PubMed

    Simeone, Regina M; Feldkamp, Marcia L; Reefhuis, Jennita; Mitchell, Allen A; Gilboa, Suzanne M; Honein, Margaret A; Iskander, John

    2015-10-09

    Major birth defects (birth defects) are defined as structural abnormalities, present at birth, with surgical, medical, or cosmetic importance. Each year in the United States, 3% of live births (approximately 120,000 infants) have an identifiable structural birth defect. Examples of birth defects include neural tube defects, such as spina bifida; orofacial clefts; abdominal wall defects, such as gastroschisis; and congenital heart defects, such as hypoplastic left heart syndrome. Collectively, congenital heart defects are the most common birth defects (27%), followed by musculoskeletal defects (18%), genitourinary defects (15%), orofacial defects (5%), and neural tube defects (2%).

  12. Melatonin prevents neural tube defects in the offspring of diabetic pregnancy.

    PubMed

    Liu, Shangming; Guo, Yuji; Yuan, Qiuhuan; Pan, Yan; Wang, Liyan; Liu, Qian; Wang, Fuwu; Wang, Jingjing; Hao, Aijun

    2015-11-01

    Melatonin, an endogenous neurohormone secreted by the pineal gland, has a variety of physiological functions and neuroprotective effects. However, its protective role on the neural tube defects (NTDs) was not very clear. The aim of this study was to investigate the effects of melatonin on the incidence of NTDs (including anencephaly, encephalocele, and spina bifida) of offspring from diabetic pregnant mice as well as its underlying mechanisms. Pregnant mice were given 10 mg/kg melatonin by daily i.p. injection from embryonic day (E) 0.5 until being killed on E11.5. Here, we showed that melatonin decreased the NTDs (especially exencephaly) rate of embryos exposed to maternal diabetes. Melatonin stimulated proliferation of neural stem cells (NSCs) under hyperglycemic condition through the extracellular regulated protein kinases (ERK) pathway. Furthermore, as a direct free radical scavenger, melatonin decreased apoptosis of NSCs exposed to hyperglycemia. In the light of these findings, it suggests that melatonin supplementation may play an important role in the prevention of neural malformations in diabetic pregnancy.

  13. Understanding the causes and prevention of neural tube defects: Insights from the splotch mouse model.

    PubMed

    Greene, Nicholas D E; Massa, Valentina; Copp, Andrew J

    2009-04-01

    Splotch mutant mice develop neural tube defects (NTDs), comprising exencephaly and/or spina bifida, as well as neural crest-related defects and abnormalities of limb musculature. Defects in splotch mice result from mutations in Pax3, and some human NTDs may also result from mutations in the human PAX3 gene. Pax3 encodes a transcription factor whose function may influence expression of multiple downstream genes associated with a variety of cellular properties (including apoptosis, adhesion, proliferation, and differentiation), that could be important for neural tube closure. The frequency of NTDs varies between mutant alleles and is also influenced by genetic background and environmental factors. Notably, splotch provides a model for folic acid-preventable NTDs, and conversely, dietary folate deficiency exacerbates NTDs. Understanding the molecular and cellular basis of splotch NTDs, as well as the mechanisms by which the frequency of defects is influenced by genetic and environmental factors (such as sub-optimal folate status), may provide insight into the causation of these severe congenital malformations in humans.

  14. Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force.

    PubMed

    Viswanathan, Meera; Treiman, Katherine A; Kish-Doto, Julia; Middleton, Jennifer C; Coker-Schwimmer, Emmanuel J L; Nicholson, Wanda K

    2017-01-10

    Neural tube defects are among the most common congenital anomalies in the United States. Periconceptional folic acid supplementation is a primary care-relevant preventive intervention. To review the evidence on folic acid supplementation for preventing neural tube defects to inform the US Preventive Services Task Force for an updated Recommendation Statement. MEDLINE, Cochrane Library, EMBASE, and trial registries through January 28, 2016, with ongoing surveillance through November 11, 2016; references; experts. English-language studies of folic acid supplementation in women. Excluded were poor-quality studies; studies of prepubertal girls, men, women without the potential for childbearing, and neural tube defect recurrence; and studies conducted in developing countries. Two investigators independently reviewed abstracts, full-text articles, and risk of bias of included studies. One investigator extracted data and a second checked accuracy. Because of heterogeneity, data were not pooled. Neural tube defects, harms of treatment (twinning, respiratory outcomes). A total of 24 studies (N > 58 860) were included. In 1 randomized clinical trial from Hungary initiated in 1984, incidence of neural tube defects for folic acid supplementation compared with trace element supplementation was 0% vs 0.25% (Peto odds ratio [OR], 0.13 [95% CI, 0.03-0.65]; n = 4862). Odds ratios from cohort studies recruiting participants between 1984 and 1996 demonstrated beneficial associations and ranged from 0.11 to 0.27 (n = 19 982). Three of 4 case-control studies with data from 1976 through 1998 reported ORs ranging from 0.6 to 0.7 (n > 7121). Evidence of benefit led to food fortification in the United States beginning in 1998, after which no new prospective studies have been conducted. More recent case-control studies drawing from data collected after 1998 have not demonstrated a protective association consistently with folic acid supplementation, with ORs ranging from

  15. First-principles studies of native defects in olivine phosphates

    NASA Astrophysics Data System (ADS)

    Hoang, Khang; Johannes, Michelle

    2011-03-01

    Olivine phosphates Li M PO4 (M = Mn, Fe, Co, Ni) are promising candidates for rechargeable Li-ion battery electrodes because of their energy storage capacity and electrochemical and thermal stability. It is known that native defects have strong effects on the performance of olivine phosphates. Yet, the formation and migration of these defects are not fully understood, and we expect that once such understanding has been established, one can envisage a solution for improving the materials' performance. In this talk, we present our first-principles density-functional theory studies of native point defects and defect complexes in Li M PO4 , and discuss the implications of these defects on the performance of the materials. Our results also provide guidelines for obtaining different native defects in experiments.

  16. Severe respiratory complex III defect prevents liver adaptation to prolonged fasting.

    PubMed

    Kremer, Laura S; L'hermitte-Stead, Caroline; Lesimple, Pierre; Gilleron, Mylène; Filaut, Sandrine; Jardel, Claude; Haack, Tobias B; Strom, Tim M; Meitinger, Thomas; Azzouz, Hatem; Tebib, Neji; Ogier de Baulny, Hélène; Touati, Guy; Prokisch, Holger; Lombès, Anne

    2016-08-01

    complex III. Based on the comparison of the patient's phenotype with other cases of complex III defect, we propose that profound complex III defect in liver does not induce actual liver failure but impedes liver adaptation to prolonged fasting. Copyright © 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  17. [Multivitamin supplement for primary prevention of birth defects: application of a preventive clinical practice].

    PubMed

    Morin, Pascale; Demers, Karine; Giguère, Christine; Tribble, Denise St-Cyr; Lane, Julie

    2007-12-01

    To determine whether the recommendations health care professionals make to women of childbearing age on the importance of taking folic acid encourage these women to take folic acid supplements. Survey. The Centre de santé et de services sociaux at the Institut universitaire de gériatrie de Sherbrooke in Sherbrooke, Que. A total of 323 Francophone women 18 to 45 years old. Whether or not women had consumed vitamin and mineral supplements during the past year. Descriptive, bivariate statistical analyses and logistic regression modeling were carried out to determine whether the association between health care professionals' recommendations and the consumption of vitamin and mineral supplements persisted after controlling for certain variables (consulting documentation, knowledge, sources of information, perception, age, education, income, marital status, and plans to become pregnant). About 41% of the women reported that their physicians had recommended that they take vitamin and mineral supplements. After adjusting for all the variables in the model, it became clear that there was a significant association between the recommendations of healthcare professionals and the consumption of vitamins and minerals by women of childbearing age. Health care professionals can improve the health of the population through preventive clinical practices. It is important that we support them in their efforts to integrate and apply scientific knowledge in their practice.

  18. [Folic acid use by pregnant women in Israel for preventing neural tube defects].

    PubMed

    Gil, Z; Aran, A; Friedman, O; Beni-Adani, L; Constantini, S

    2000-12-01

    Spina bifida and anencephaly are the most common, serious malformations in neural tube defects (NTD). Randomized trials in the last 2 decades have demonstrated that folic acid, 0.4 mg/d, reduces the incidence of NTD by more than 50%. We investigated the use of folic acid and multivitamins containing folic acid in childbearing women. Of 221 women interviewed, 67 (30%) regularly took pills containing 0.4 mg folic acid. Women with higher educational levels were more likely to take multivitamins with folic acid than were the less educated (p = 0.05). Of the women who took folic acid, only 5 (7.5%) used separate folic acid tablets, before and during their pregnancy. The rest used multivitamins containing folic acid. The 5 women who took folic acid separately were college-educated and nonreligious, and they took multivitamins in addition (p > 0.05). Of the women interviewed, 58 (26.2%) were Bedouin of the Negev. 24 (41.4%) of them took pills containing folic acid on a regular basis. This percentage is higher than that in the Jewish women in the study who took folic acid for prevention of NTD (17%; p = 0.038). Most of the women took folic acid after the first trimester. Only a minority took daily periconceptional folic acid. Multivitamins containing 0.4 mg of folic acid were more popular than folic acid tablets alone. This study emphasizes the need for continuing efforts to increase consumption of folic acid and awareness of its benefits among women of childbearing age.

  19. Positron studies of defected metals, metallic surfaces

    SciTech Connect

    Bansil, A.

    1991-01-01

    Specific problems proposed under this project included the treatment of electronic structure and momentum density in various disordered and defected systems. Since 1987, when the new high-temperature superconductors were discovered, the project focused extensively on questions concerning the electronic structure and Fermiology of high-[Tc] superconductors, in particular, (i) momentum density and positron experiments, (ii) angle-resolved photoemission intensities, (iii) effects of disorder and substitutions in the high-[Tc]'s.

  20. Evaluation and Visualization of Surface Defects - a Numerical and Experimental Study on Sheet-Metal Parts

    SciTech Connect

    Andersson, A.

    2005-08-05

    The ability to predict surface defects in outer panels is of vital importance in the automotive industry, especially for brands in the premium car segment. Today, measures to prevent these defects can not be taken until a test part has been manufactured, which requires a great deal of time and expense. The decision as to whether a certain surface is of acceptable quality or not is based on subjective evaluation. It is quite possible to detect a defect by measurement, but it is not possible to correlate measured defects and the subjective evaluation. If all results could be based on the same criteria, it would be possible to compare a surface by both FE simulations, experiments and subjective evaluation with the same result.In order to find a solution concerning the prediction of surface defects, a laboratory tool was manufactured and analysed both experimentally and numerically. The tool represents the area around a fuel filler lid and the aim was to recreate surface defects, so-called 'teddy bear ears'. A major problem with the evaluation of such defects is that the panels are evaluated manually and to a great extent subjectivity is involved in the classification and judgement of the defects. In this study the same computer software was used for the evaluation of both the experimental and the numerical results. In this software the surface defects were indicated by a change in the curvature of the panel. The results showed good agreement between numerical and experimental results. Furthermore, the evaluation software gave a good indication of the appearance of the surface defects compared to an analysis done in existing tools for surface quality measurements. Since the agreement between numerical and experimental results was good, this indicates that these tools can be used for an early verification of surface defects in outer panels.

  1. Maternal Exposure to Methotrexate and Birth Defects: a Population-Based Study

    PubMed Central

    Dawson, April L.; Riehle-Colarusso, Tiffany; Reefhuis, Jennita; Arena, J. Fernando

    2015-01-01

    Methotrexate is an anti-folate medication that is associated with increased risk of multiple birth defects. Using data from the National Birth Defects Prevention Study, a case-control study of major birth defects in the United States, we examined mothers exposed to methotrexate. The study population included mothers of live-born infants without major birth defects (controls) and mothers of fetuses or infants with a major birth defect (cases), with expected dates of delivery between October 1997 and December 2009. Mothers of cases and controls were asked detailed questions concerning pregnancy history, demographic information, and exposures in a telephone interview. Approximately 0.06% (n=16/27,623) of case and 0.04% (n=4/10,113) of control mothers reported exposure to methotrexate between three months prior to conception through the end of pregnancy. Of the 16 case infants, 11 (68.8%) had a congenital heart defect (CHD). The observed CHDs included atrial septal defects, tetralogy of Fallot, valvar pulmonary stenosis, ventricular septal defects (VSDs), and total anomalous pulmonary venous return. One case infant had microtia in addition to a VSD and another had VACTER association. Exposed cases without a CHD had one of the following birth defects: cleft palate, hypospadias, congenital diaphragmatic hernia, or craniosynostosis. Based on a limited number of methotrexate-exposed mothers, our findings support recent case reports suggesting an association between early pregnancy exposure to methotrexate and CHDs. Because of the rarity of maternal periconceptional exposure to methotrexate, long-term, population-based case-control studies are needed to confirm these findings and better evaluate the association between methotrexate and birth defects. PMID:24898111

  2. Prevention of neural tube defects by folic acid - awareness among women of childbearing age in Slovakia.

    PubMed

    Horn, F; Sabova, L; Pinterova, E; Hornova, J; Trnka, J

    2014-01-01

    Folic acid deficiency plays a central role in the aetiology of many congenital anomalies including neural tube defects. Protective effect of folic acid on embryo may be acquired only if taken periconceptionally. The aim of the study was to investigate the awareness about folic acid among women of childbearing age in Bratislava, Slovakia. There were 130 respondents involved in the research (106 pregnant women, 24 female students of medical faculty). Using questionnaire we acquired following data: pregnancy details, interest in diet before and during pregnancy, recommendations regarding nutrition and supplementation pre- and post-conception, knowledge about folic and other acid in 2004 and 2009. More than half of the respondents knew the sources of folic acid. The interest in the nutrition facts of the food dropped from 91 % to 58.5 %. The number of pregnant women advised about correct nutrition and folic acid supplementation before and during pregnancy increased from 16 % to 37 %. Planning the next gravidity with folic acid supplementation became greater than 21 % (38 % in 2009). Nevertheless, only 46 % of these women believed that proper food content with folic acid may prevent congenital anomalies. In a group of students planning to take folic acid periconceptionally the number raised up to 62.5 %. The results revealed low knowledge about the effect of folic acid on developing embryo among women of childbearing age. Effective intervention programs are needed with the aim to improve periconceptional intake of folic acid in 2004 and 2009. The results in both periods show low knowledge about this essential vitamin (Tab. 1, Fig. 8, Ref. 31).

  3. [Analysis of the Spanish situation regarding folic acid/calcic folinate consumption for birth defects prevention].

    PubMed

    Martínez-Frías, M Luisa; Rodríguez-Pinilla, Elvira; Bermejo, Eva

    2003-12-06

    Since 1992, the recommendation on the ingestion of folic acid (FA) to prevent congenital defects has become general in developed countries. In this paper, we analyze such a situation in Spain in most recent years. We used the information concerning mothers of infants selected as controls in the ECEMC database. These mothers make up a sample of pregnant women of the general population. We analyzed the evolution of the consumption of FA/calcic folinate (CF) by pregnant women over the last 22 years, considering the period of pregnancy during which this vitamin was taken and the dosage. The proportion of women who take FA/CF during the first trimester of pregnancy increased dramatically in the last 9 years, up to 80% in 2002. However, only about 9% took the vitamin before becoming pregnant. Moreover, many daily doses are much higher than those internationally recommended for the general population of women planning pregnancy. In our country, the use of FA/CF to prevent congenital defects is correct in a small part of the population of pregnant women. Therefore, it is necessary to continue disseminating appropriate guidelines not only among gynecologists but also among family and general practitioners and health professionals working at family planning centers. Thus, they can transmit to women the need of using FA/CF and the right way to do it.

  4. Making birth defects 'preventable': pre-conceptional vitamin supplements and the politics of risk reduction.

    PubMed

    Al-Gailani, Salim

    2014-09-01

    Since the mid-1990s, governments and health organizations around the world have adopted policies designed to increase women's intake of the B-vitamin 'folic acid' before and during the first weeks of pregnancy. Building on initial clinical research in the United Kingdom, folic acid supplementation has been shown to lower the incidence of neural tube defects (NTDs). Recent debate has focused principally on the need for mandatory fortification of grain products with this vitamin. This article takes a longer view, tracing the transformation of folic acid from a routine prenatal supplement to reduce the risk of anaemia to a routine 'pre-conceptional' supplement to 'prevent' birth defects. Understood in the 1950s in relation to social problems of poverty and malnutrition, NTDs were by the end of the century more likely to be attributed to individual failings. This transition was closely associated with a second. Folic acid supplements were initially prescribed to 'high-risk' women who had previously borne a child with a NTD. By the mid-1990s, they were recommended for all women of childbearing age. The acceptance of folic acid as a 'risk-reducing drug' both relied upon and helped to advance the development of preventive and clinical practices concerned with women's health before pregnancy.

  5. A single-molecule approach to ZnO defect studies: Single photons and single defects

    SciTech Connect

    Jungwirth, N. R.; Pai, Y. Y.; Chang, H. S.; MacQuarrie, E. R.; Nguyen, K. X.; Fuchs, G. D.

    2014-07-28

    Investigations that probe defects one at a time offer a unique opportunity to observe properties and dynamics that are washed out of ensemble measurements. Here, we present confocal fluorescence measurements of individual defects in ZnO nanoparticles and sputtered films that are excited with sub-bandgap energy light. Photon correlation measurements yield both antibunching and bunching, indicative of single-photon emission from isolated defects that possess a metastable shelving state. The single-photon emission is in the range of ∼560–720 nm and typically exhibits two broad spectral peaks separated by ∼150 meV. The excited state lifetimes range from 1 to 13 ns, consistent with the finite-size and surface effects of nanoparticles and small grains. We also observe discrete jumps in the fluorescence intensity between a bright state and a dark state. The dwell times in each state are exponentially distributed and the average dwell time in the bright (dark) state does (may) depend on the power of the exciting laser. Taken together, our measurements demonstrate the utility of a single-molecule approach to semiconductor defect studies and highlight ZnO as a potential host material for single-defect based applications.

  6. A single-molecule approach to ZnO defect studies: Single photons and single defects

    NASA Astrophysics Data System (ADS)

    Jungwirth, N. R.; Pai, Y. Y.; Chang, H. S.; MacQuarrie, E. R.; Nguyen, K. X.; Fuchs, G. D.

    2014-07-01

    Investigations that probe defects one at a time offer a unique opportunity to observe properties and dynamics that are washed out of ensemble measurements. Here, we present confocal fluorescence measurements of individual defects in ZnO nanoparticles and sputtered films that are excited with sub-bandgap energy light. Photon correlation measurements yield both antibunching and bunching, indicative of single-photon emission from isolated defects that possess a metastable shelving state. The single-photon emission is in the range of ˜560-720 nm and typically exhibits two broad spectral peaks separated by ˜150 meV. The excited state lifetimes range from 1 to 13 ns, consistent with the finite-size and surface effects of nanoparticles and small grains. We also observe discrete jumps in the fluorescence intensity between a bright state and a dark state. The dwell times in each state are exponentially distributed and the average dwell time in the bright (dark) state does (may) depend on the power of the exciting laser. Taken together, our measurements demonstrate the utility of a single-molecule approach to semiconductor defect studies and highlight ZnO as a potential host material for single-defect based applications.

  7. Knowledge and practice of urban Iranian pregnant women towards folic acid intake for neural tube defect prevention.

    PubMed

    Nosrat, Sepideh Bakhshande; Sedehi, Maliheh; Golalipour, Mohammad Jafar

    2012-08-01

    To assess the knowledge and practice of urban Iranian pregnant women regarding periconceptional folic acid intake for neural tube defect (NTD) prevention. The population-based study was done on 676 primiparous women in an urban area in Golestan province in northern Iran from June to November, 2008. A questionnaire was completed by the subjects regarding their knowledge of folic acid. Questionnaires were administered to women who were seeking routine antenatal care at health centres, private gynaecological clinic and the Dezyani Gynaecologic and Obstetric Hospital. Questions covered knowledge and use of folic acid supplements and demographic and socioeconomic characteristics. Out of the 676 women surveyed, 96.2% reported that they heard of folate. Of these, only 27.6% knew that folate was something important in the prevention of neural tube defects. Overall, 20.12% of the total women took folic acid during periconceptional period. The most common information sources on folate were healthcare service (54.5%). Besides, 37.6% of the subjects who heard about folate were aware that green leafy vegetables were fortified with folic acid. In univariate analysis, knowledge and intake of folic acid was not associated with education and the age of women. A healthcare plan for intervention to increase the knowledge and intake of folic acid by pregnant women during the protective period is required.

  8. Prevention of birth defects in the pre-conception period: knowledge and practice of health care professionals (nurses and doctors) in a city of Southern Brazil

    PubMed Central

    Ferreira, Flávia Romariz; Russo Akiba, Heloisa Regina; Júnior, Edward Araujo; Figueiredo, Elisabeth Niglio; Abrahão, Anelise Riedel

    2015-01-01

    Background: Some congenital defects can be prevented in the pregestational stage. However, many health professionals are not prepared to provide counselling to couples regarding the same. Objective: This study aimed to assess the performance of doctors and nurses from a primary health-care unit in Florianopolis, Brazil, in preventing birth defects in the preconception period based on the recommendations of the Control Center of Disease Prevention. Materials and Methods: This descriptive cross sectional study was performed at a tertiary referral center. In this study, a semi-structured questionnaire was provided to 160 health professionals comprising doctors and nurses who were actively involved in providing primary health care in family health programs. The non-parametric Chi-square (χ2) test was used to analyse the data obtained through multiple choice questions. Results: Our results showed that although 81.9% of health professionals provided health-care assistance based on protocols, and only 46.2% professionals were aware of the presence of the topic in the protocol. Of the recommendations provided by the Control Center of Disease Prevention, the use of folic acid was the most prescribed. However, this prescription was not statistically different between nurses and doctors (P=0.85). Conclusion: This study identified the fragile nature in these professional’s knowledge about the prevention of birth defects in pre-conception period, as evidenced by the inconsistency in their responses. PMID:26644794

  9. Diffusion and Defect Characterization Studies of Mercury Cadmium Telluride

    DTIC Science & Technology

    1989-08-01

    Mercury Cadmium Telluride" Principal Investigator: D. A. Stevenson Department of Materials Science and Engineering Stanford University Stanford, CA 94305...Include Security Classificatton, Difuson Defect Characterization Studies of Mercury Cadmium Telluride 12 PERSONAL AUTHOR(S) ProfessJL Ddvid A. Stevenson 13a...diffusion and defect chemistry of mercury cadmium telluride (MCT; Hg Cd Te). In this study, we have measured tracer self- diffusion and interdiffusion

  10. Challenges in Studying Modifiable Risk Factors for Birth Defects.

    PubMed

    Tinker, Sarah C; Gilboa, Suzanne; Reefhuis, Jennita; Jenkins, Mary M; Schaeffer, Marcy; Moore, Cynthia A

    2015-03-01

    Conducting research to identify modifiable risk factors for birth defects is difficult for a variety of reasons. While some challenges are familiar to researchers across many disciplines, the confluence of issues affecting birth defects research may not be well understood by those outside of the field. This article describes several methodological challenges to the study of birth defects and ways these challenges might be addressed: (1) ascertainment, definition and classification of birth defects; (2) exposure assessment on modifiable risk factors; (3) analytical challenges related to small numbers and multiple statistical tests; (4) the role of genetics, including the collection of specimens and analysis of genetic data; and (5) challenges in translating research and demonstrating public health impact. Understanding these issues is important for researchers planning studies, reviewers evaluating the scientific merit of results from these studies, and consumers of the research, including fellow researchers, policy makers, health care providers, and families.

  11. Challenges in Studying Modifiable Risk Factors for Birth Defects

    PubMed Central

    Gilboa, Suzanne; Reefhuis, Jennita; Jenkins, Mary M.; Schaeffer, Marcy; Moore, Cynthia A.

    2015-01-01

    Conducting research to identify modifiable risk factors for birth defects is difficult for a variety of reasons. While some challenges are familiar to researchers across many disciplines, the confluence of issues affecting birth defects research may not be well understood by those outside of the field. This article describes several methodological challenges to the study of birth defects and ways these challenges might be addressed: (1) ascertainment, definition and classification of birth defects; (2) exposure assessment on modifiable risk factors; (3) analytical challenges related to small numbers and multiple statistical tests; (4) the role of genetics, including the collection of specimens and analysis of genetic data; and (5) challenges in translating research and demonstrating public health impact. Understanding these issues is important for researchers planning studies, reviewers evaluating the scientific merit of results from these studies, and consumers of the research, including fellow researchers, policy makers, health care providers, and families. PMID:26236577

  12. Folic acid prevents neural tube defects: international comparison of awareness among obstetricians/gynecologists and urologists.

    PubMed

    Kondo, Atsuo; Kamihira, Osamu; Gotoh, Momokazu; Ozawa, Hideo; Lee, Tchun Yong; Lin, Alex T-L; Kim, Seung-Ryong; Lin, Ho-Hsiung

    2007-02-01

    It has been suggested that periconceptional intake of folic acid prevents risks of having fetuses afflicted with neural tube defects. We aim to internationally investigate knowledge of the role of folic acid and attitudes toward the life-style of young women of child-bearing age among obstetricians/gynecologists and urologists. A questionnaire was sent to obstetricians/gynecologists and urologists residing in Japan, South Korea, Taiwan, North America, Europe, Australia and New Zealand by post or e-mail. The investigation was conducted between December 2002 and November 2004. A mean of 91% of obstetricians/gynecologists and 56% of urologists are aware of the role of folic acid, where Asian urologists knew less compared to those of North America, Europe, Australia and New Zealand. A majority of doctors always, or occasionally, recommend folic acid supplements or multivitamins, well-balanced meals, and the cessation of smoking and drinking. An average of 85% of doctors believes information on folic acid should be disseminated to young women. A majority of obstetricians/gynecologists and urologists know the importance of periconceptional folic acid in reducing the risk of neural tube defects and have been advising young women to improve their lifestyle.

  13. Folic Acid supplementation and pregnancy: more than just neural tube defect prevention.

    PubMed

    Greenberg, James A; Bell, Stacey J; Guan, Yong; Yu, Yan-Hong

    2011-01-01

    Folate (vitamin B(9)) is an essential nutrient that is required for DNA replication and as a substrate for a range of enzymatic reactions involved in amino acid synthesis and vitamin metabolism. Demands for folate increase during pregnancy because it is also required for growth and development of the fetus. Folate deficiency has been associated with abnormalities in both mothers (anemia, peripheral neuropathy) and fetuses (congenital abnormalities). This article reviews the metabolism of folic acid, the appropriate use of folic acid supplementation in pregnancy, and the potential benefits of folic acid, as well as the possible supplementation of l-methylfolate for the prevention of pregnancy-related complications other than neural tube defects.

  14. Crystal defect studies using x-ray diffuse scattering

    SciTech Connect

    Larson, B.C.

    1980-01-01

    Microscopic lattice defects such as point (single atom) defects, dislocation loops, and solute precipitates are characterized by local electronic density changes at the defect sites and by distortions of the lattice structure surrounding the defects. The effect of these interruptions of the crystal lattice on the scattering of x-rays is considered in this paper, and examples are presented of the use of the diffuse scattering to study the defects. X-ray studies of self-interstitials in electron irradiated aluminum and copper are discussed in terms of the identification of the interstitial configuration. Methods for detecting the onset of point defect aggregation into dislocation loops are considered and new techniques for the determination of separate size distributions for vacancy loops and interstitial loops are presented. Direct comparisons of dislocation loop measurements by x-rays with existing electron microscopy studies of dislocation loops indicate agreement for larger size loops, but x-ray measurements report higher concentrations in the smaller loop range. Methods for distinguishing between loops and three-dimensional precipitates are discussed and possibilities for detailed studies considered. A comparison of dislocation loop size distributions obtained from integral diffuse scattering measurements with those from TEM show a discrepancy in the smaller sizes similar to that described above.

  15. Diabetes mellitus and birth defects

    PubMed Central

    Correa, Adolfo; Gilboa, Suzanne M.; Besser, Lilah M.; Botto, Lorenzo D.; Moore, Cynthia A.; Hobbs, Charlotte A.; Cleves, Mario A.; Riehle-Colarusso, Tiffany J.; Waller, D. Kim; Reece, E. Albert

    2016-01-01

    OBJECTIVE The purpose of this study was to examine associations between diabetes mellitus and 39 birth defects. STUDY DESIGN This was a multicenter case-control study of mothers of infants who were born with (n = 13,030) and without (n = 4895) birth defects in the National Birth Defects Prevention Study (1997–2003). RESULTS Pregestational diabetes mellitus (PGDM) was associated significantly with noncardiac defects (isolated, 7/23 defects; multiples, 13/23 defects) and cardiac defects (isolated, 11/16 defects; multiples, 8/16 defects). Adjusted odds ratios for PGDM and all isolated and multiple defects were 3.17 (95% CI, 2.20–4.99) and 8.62 (95% CI, 5.27–14.10), respectively. Gestational diabetes mellitus (GDM) was associated with fewer noncardiac defects (isolated, 3/23 defects; multiples, 3/23 defects) and cardiac defects (isolated, 3/16 defects; multiples, 2/16 defects). Odds ratios between GDM and all isolated and multiple defects were 1.42 (95% CI, 1.17–1.73) and 1.50 (95% CI, 1.13–2.00), respectively. These associations were limited generally to offspring of women with prepregnancy body mass index ≥25 kg/m2. CONCLUSION PGDM was associated with a wide range of birth defects; GDM was associated with a limited group of birth defects. PMID:18674752

  16. Nitrotyrosine adsorption on defective graphene: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Majidi, R.; Karami, A. R.

    2015-06-01

    We have applied density functional theory to study adsorption of nitrotyrosine on perfect and defective graphene sheets. The graphene sheets with Stone-Wales (SW) defect, pentagon-nonagon (5-9) single vacancy, and pentagon-octagon-pentagon (5-8-5) double vacancy were considered. The calculations of adsorption energy showed that nitrotyrosine presents a more strong interaction with defective graphene rather than with perfect graphene sheet. The order of interaction strength is: SW>5-9>5-8-5>perfect graphene. It is found that the electronic properties of perfect and defective graphene are sensitive to the presence of nitrotyrosine. Hence, graphene sheets can be considered as a good sensor for detection of nitrotyrosine molecule which is observed in connection with several human disorders, such as Parkinson's and Alzheimer's disease.

  17. Factors affecting maternal participation in the genetic component of the National Birth Defects Prevention Study—United States, 1997–2007

    PubMed Central

    Glidewell, Jill; Reefhuis, Jennita; Rasmussen, Sonja A.; Woomert, Alison; Hobbs, Charlotte; Romitti, Paul A.; Crider, Krista S.

    2015-01-01

    Purpose As epidemiological studies expand to examine gene–environment interaction effects, it is important to identify factors associated with participation in genetic studies. The National Birth Defects Prevention Study is a multisite case–control study designed to investigate environmental and genetic risk factors for major birth defects. The National Birth Defects Prevention Study includes maternal telephone interviews and mailed buccal cell self-collection kits. Because subjects can participate in the interview, independent of buccal cell collection, detailed analysis of factors associated with participation in buccal cell collection was possible. Methods Multivariable logistic regression models were used to identify the factors associated with participation in the genetic component of the study. Results Buccal cell participation rates varied by race/ethnicity (non-Hispanic whites, 66.9%; Hispanics, 60.4%; and non-Hispanic blacks, 47.3%) and study site (50.2–74.2%). Additional monetary incentive following return of buccal cell kit and shorter interval between infant’s estimated date of delivery and interview were associated with increased participation across all racial/ethnic groups. Higher education and delivering an infant with a birth defect were associated with increased participation among non-Hispanic whites and Hispanics. Conclusion Factors associated with participation varied by race/ethnicity. Improved understanding of factors associated with participation may facilitate strategies to increase participation, thereby improving generalizability of study findings. PMID:24071796

  18. Defective pyrite (100) surface: An ab initio study

    SciTech Connect

    Stirling, Andras; Bernasconi, Marco; Parrinello, Michele

    2007-04-15

    The structural and electronic properties of sulfur monomeric defects at the FeS{sub 2}(100) surface have been studied by periodic density-functional calculations. We have shown that for a monomeric sulfur bound to an originally fivefold coordinated surface Fe site, the defect core features a triplet electronic ground state with unpaired spins localized on the exposed Fe-S unit. At this site, the iron and sulfur ions have oxidation states +4 and -2, respectively. This defect can be seen as produced via heterolytic bond breaking of the S-S sulfur dimer followed by a Fe-S redox reaction. The calculated sulfur 2p core-level shifts of the monomeric defects are in good agreement with experimental photoemission spectra, which allow a compelling assignment of the different spectroscopic features. The effect of water on the stability of the defective surface has also been studied, and it has been shown that the triplet state is stable against the wetting of the surface. The most important implications of the presence of the monomeric sulfur defect on the reactivity are also discussed.

  19. Myo-inositol soft gel capsules may prevent the risk of coffee-induced neural tube defects.

    PubMed

    De Grazia, Sara; Carlomagno, Gianfranco; Unfer, Vittorio; Cavalli, Pietro

    2012-09-01

    Neural tube defects (NTDs) are classified as folate sensitive (about 70%) and folate resistant (about 30%); although folic acid is able to prevent the former, several data have shown that inositol may prevent the latter. It has recently been proposed that coffee intake might represent a risk factor for NTD, likely by interfering with the inositol signaling. In the present study, we tested the hypothesis that, beside affecting the inositol signaling pathway, coffee also interferes with inositol absorption. In order to evaluate coffee possible negative effects on inositol gastrointestinal absorption, a single-dose bioavailability trial was conducted. Pharmacokinetics (PK) parameters of myo-inositol (MI) powder and MI soft gelatin capsules swallowed with water and with a single 'espresso' were compared. PK profiles were obtained by analysis of MI plasma concentration, and the respective MI bioavailability was compared. Myo-inositol powder administration was negatively affected by coffee intake, thus suggesting an additional explanation to the interference between inositol deficiency and coffee consumption. On the contrary, the concomitant single 'espresso' consumption did not affect MI absorption following MI soft gelatin capsules administration. Furthermore, it was observed that MI soft gelatin capsule administration resulted in improved bioavailability compared to the MI powder form. Myo-inositol soft gelatin capsules should be considered for the preventive treatment of NTDs in folate-resistant subjects due to their higher bioavailability and to the capability to reduce espresso interference.

  20. Controlled samples for silicon defect and impurity studies

    SciTech Connect

    Ciszek, T.F.

    1995-08-01

    Because of the diverse defects and impurities that are present in any given sample of silicon material, it can be extremely difficult to conduct a controlled experiment to study the influence of any particular defect or impurity on photovoltaic properties such as minority charge carrier lifetime {tau} or solar cell efficiency q. For example, the influence of iron may be different if boron is present, or the influence of silicon self interstitial clusters may be different if oxygen is present. It thus becomes important to conduct such studies on controlled samples where the influence of secondary effects is minimized. At NREL, over the past several years, we have focused on using the high-purity float-zone (FZ) growth method to obtain controlled samples. Because the silicon melt is not in contact with a container, and no heated components are in the growth region, very high purities and low defect levels can be achieved in baseline material. The baseline can be controllably perturbed by introduction of specific defects or impurities. The chart shown below lists some of the types of defect and impurity. combinations that can be studied in this way. The boxes marked with an {open_quotes}x{close_quotes} represent combinations we have studied to some extent.

  1. The use of folic acid for the prevention of neural tube defects and other congenital anomalies.

    PubMed

    Wilson, R Douglas; Davies, Gregory; Désilets, Valérie; Reid, Gregory J; Summers, Anne; Wyatt, Philip; Young, David

    2003-11-01

    To provide information regarding the use of folic acid for the prevention of neural tube defects (NTDs) and other congenital anomalies, in order that physicians, midwives, nurses, and other health-care workers can assist in the education of women in the preconception phase of their health care. OPTION: Folic acid supplementation is problematic, since 50% of pregnancies are unplanned and the health status of women may not be optimal. Folic acid supplementation has been proven to decrease or minimize specific birth defects. A systematic review of the literature, including review and peer-reviewed articles, government publications, the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) Policy Statement of March 1993, and statements from the American College of Obstetrics and Gynecology, was used to develop a new clinical practice guideline for the SOGC. Peer-review process within the committee structure. The benefit is reduced lethal and severe morbidity birth defects and the harm is minimal. The personal cost is of vitamin supplementation on a daily basis and eating a healthy diet. 1. Women in the reproductive age group should be advised about the benefits of folic acid supplementation during wellness visits (birth control renewal, Pap testing, yearly examination), especially if pregnancy is contemplated. (III-A) 2. Women should be advised to maintain a healthy nutritional diet, as recommended in Canada's Food Guide to Healthy Eating (good or excellent sources of folic acid: broccoli, spinach, peas, Brussels sprouts, corn, beans, lentils, oranges). (III-A) 3. Women who could become pregnant should be advised to take a multivitamin containing 0.4 mg to 1.0 mg of folic acid daily. (II-1A) 4. Women taking a multivitamin with folic acid supplement should be advised not to take more than 1 daily dose of vitamin supplement, as indicated on the product label. (II-2A) 5. Women in intermediate- to high-risk categories for NTDs (NTD-affected previous

  2. The role of oxidized regenerate cellulose to prevent cosmetic defects in oncoplastic breast surgery.

    PubMed

    Franceschini, G; Visconti, G; Terribile, D; Fabbri, C; Magno, S; Di Leone, A; Salgarello, M; Masetti, R

    2012-07-01

    Breast conserving surgery (BCS) combined with postoperative radiotherapy has become the gold standard of locoregional treatment for the majority of patients with early-stage breast cancer, offering equivalent survival and improved body image and lifestyle scores as compared to mastectomy. In an attempt to optimize the oncologic safety and cosmetic results of BCS, oncoplastic procedures (OPP) have been introduced in recent years combining the best principles of surgical oncology with those of plastic surgery. However, even with the use of OPP, cosmetic outcomes may result unsatisfying when a large volume of parenchyma has to be removed, particularly in small-medium size breasts. The aim of this article is to report our preliminary results with the use of oxidized regenerate cellulose (ORC) (Tabotamp fibrillar, Johnson & Johnson; Ethicon, USA) as an agent to prevent cosmetic defects in patients undergoing OPP for breast cancer and to analyze the technical refinements that can enhance its efficacy in optimizing cosmetic defects. Different OPP are selected based on the location and size of the tumor as well as volume and shape of the breast. After excision of the tumor, glandular flaps are created by dissection of the residual parenchyma from the pectoralis and serratus muscles and from the skin. After careful haemostasis, five layers of ORC are positioned on the pectoralis major in the residual cavity and covered by advancement of the glandular flaps. Two additional layers of ORC are positioned above the flaps and covered by cutaneous-subcutaenous flaps. The use of ORC after OPP has shown promising preliminary results, indicating a good tolerability and positive effects on cosmesis. This simple and reliable surgical technique may allow not only to reduce the rate of post-operative bleeding and infection at the surgical site but also to improve cosmetic results.

  3. Hybrid functional studies of defects in layered transition metal oxides

    NASA Astrophysics Data System (ADS)

    Hoang, Khang; Johannes, Michelle

    2014-03-01

    Layered oxides LiMO2 (M is a transition metal) have been studied extensively for Li-ion battery cathodes. It is known that defects have strong impact on the electrochemical performance. A detailed understanding of native point defects in LiMO2 is however still lacking, thus hindering rational design of more complex materials for battery applications. In fact, first-principles defect calculations in LiMO2 are quite challenging because standard density functional theory (DFT) calculations using the generalized gradient approximation (GGA) of the exchange-correlation functional fail to reproduce the correct physics. The GGA+U extension can produce reasonable results, but the transferability of U across the compounds is limited. In this talk, we present our DFT studies of defects in LiMO2 (M=Co, Ni) using the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional. The dominant point defects will be identified and compared with experiment; and their impact on the structural stability and the charge (electronic and ionic) and mass transport will be addressed. We will also discuss possible shortcomings of the HSE functional in the study of these electron-correlated materials.

  4. Defect studies in low-temperature-grown GaAs

    SciTech Connect

    Bliss, D.E.

    1992-11-01

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

  5. Defect studies in low-temperature-grown GaAs

    SciTech Connect

    Bliss, David Emory

    1992-11-01

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies VGa. The neutral AsGa-related defects were measured by infrared absorption at 1μm. Gallium vacancies, VGa, was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 1019 cm-3 Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more AsGa in the layer. As AsGa increases, photoquenchable AsGa decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral AsGa content around 500C, similar to irradiation damaged and plastically deformed GaAs, as opposed to bulk grown GaAs in which AsGa-related defects are stable up to 1100C. The lower temperature defect removal is due to VGa enhanced diffusion of AsGa to As precipitates. The supersaturated VGa and also decreases during annealing. Annealing kinetics for AsGa-related defects gives 2.0 ± 0.3 eV and 1.5 ± 0.3 eV migration enthalpies for the AsGa and VGa. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable AsGa-related defects anneal with an activation energy of 1.1 ± 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of AsGa-BeGa pairs. Si donors can only be partially activated.

  6. Resolvability of defect ensembles with positron annihilation studies

    SciTech Connect

    Fluss, M.J.; Howell, R.H.; Rosenberg, I.J.; Meyer, P.

    1984-11-12

    Recent advances in the use of positron annihilation to study defect ensembles in and on the surfaces of metals, are pointing the way towards studies where particular positron-electron annihilation modes may be identified and studied in the presence of one another. Although a great deal is understood about the annihilation of positrons in ostensibly defect-free metals, much less is understood when the positron annihilates in complex defect systems such as liquid metals, amorphous solids, or at or near the vacuum-solid interface. In this paper the results of three experiments, all of which demonstrate means by which we can resolve various poistron annihilation channels from one another, are discussed.

  7. Adjusting for bias due to incomplete case ascertainment in case-control studies of birth defects.

    PubMed

    Howards, Penelope P; Johnson, Candice Y; Honein, Margaret A; Flanders, W Dana

    2015-04-15

    Case-control studies of birth defects might be subject to selection bias when there is incomplete ascertainment of cases among pregnancies that are terminated after a prenatal diagnosis of the defect. We propose a simple method to estimate inverse probability of selection weights (IPSWs) for cases ascertained from both pregnancies that end in termination and those that do not end in termination using data directly available from the National Birth Defects Prevention Study and other published information. The IPSWs can then be used to adjust for selection bias analytically. We can also allow for uncertainty in the selection probabilities through probabilistic bias analysis. We provide an illustrative example using data from National Birth Defects Prevention Study (1997-2009) to examine the association between prepregnancy obesity (body mass index, measured as weight in kilograms divided by height in meters squared, of ≥30 vs. <30) and spina bifida. The unadjusted odds ratio for the association between prepregnancy obesity and spina bifida was 1.48 (95% confidence interval: 1.26, 1.73), and the simple selection bias-adjusted odds ratio was 1.26 (95% confidence interval: 1.04, 1.53). The probabilistic bias analysis resulted in a median adjusted odds ratio of 1.22 (95% simulation interval: 0.97, 1.47). The proposed method provides a quantitative estimate of the IPSWs and the bias introduced by incomplete ascertainment of cases among terminated pregnancies conditional on a set of assumptions.

  8. Point defects in thorium nitride: A first-principles study

    NASA Astrophysics Data System (ADS)

    Pérez Daroca, D.; Llois, A. M.; Mosca, H. O.

    2016-11-01

    Thorium and its compounds (carbides and nitrides) are being investigated as possible materials to be used as nuclear fuels for Generation-IV reactors. As a first step in the research of these materials under irradiation, we study the formation energies and stability of point defects in thorium nitride by means of first-principles calculations within the framework of density functional theory. We focus on vacancies, interstitials, Frenkel pairs and Schottky defects. We found that N and Th vacancies have almost the same formation energy and that the most energetically favorable defects of all studied in this work are N interstitials. These kind of results for ThN, to the best authors' knowledge, have not been obtained previously, neither experimentally, nor theoretically.

  9. Prevention of neural tube defects with folic acid: The Chinese experience.

    PubMed

    Ren, Ai-Guo

    2015-08-08

    Neural tube defects (NTDs) are a group of congenital malformations of the central nervous system that are caused by the closure failure of the embryonic neural tube by the 28(th) day of conception. Anencephaly and spina bifida are the two major subtypes. Fetuses with anencephaly are often stillborn or electively aborted due to prenatal diagnosis, or they die shortly after birth. Most infants with spina bifida are live-born and, with proper surgical treatment, can survive into adulthood. However, these children often have life-long physical disabilities. China has one of the highest prevalence of NTDs in the world. Inadequate dietary folate intake is believed to be the main cause of the cluster. Unlike many other countries that use staple fortification with folic acid as the public health strategy to prevent NTDs, the Chinese government provides all women who have a rural household registration and who plan to become pregnant with folic acid supplements, free of charge, through a nation-wide program started in 2009. Two to three years after the initiation of the program, the folic acid supplementation rate increased to 85% in the areas of the highest NTD prevalence. The mean plasma folate level of women during early and mid-pregnancy doubled the level before the program was introduced. However, most women began taking folic acid supplements when they knew that they were pregnant. This is too late for the protection of the embryonic neural tube. In a post-program survey of the women who reported folic acid supplementation, less than a quarter of the women began taking supplements prior to pregnancy, indicating that the remaining three quarters of the fetuses remained unprotected during the time of neural tube formation. Therefore, staple food fortification with folic acid should be considered as a priority in the prevention of NTDs.

  10. Is 5-methyltetrahydrofolate an alternative to folic acid for the prevention of neural tube defects?

    PubMed

    Obeid, Rima; Holzgreve, Wolfgang; Pietrzik, Klaus

    2013-09-01

    Women have higher requirements for folate during pregnancy. An optimal folate status must be achieved before conception and in the first trimester when the neural tube closes. Low maternal folate status is causally related to neural tube defects (NTDs). Many NTDs can be prevented by increasing maternal folate intake in the preconceptional period. Dietary folate is protective, but recommending increasing folate intake is ineffective on a population level particularly during periods of high demands. This is because the recommendations are often not followed or because the bioavailability of food folate is variable. Supplemental folate [folic acid (FA) or 5-methyltetrahydrofolate (5-methylTHF)] can effectively increase folate concentrations to the level that is considered to be protective. FA is a synthetic compound that has no biological functions unless it is reduced to dihydrofolate and tetrahydrofolate. Unmetabolized FA appears in the circulation at doses of >200 μg. Individuals show wide variations in their ability to reduce FA. Carriers of certain polymorphisms in genes related to folate metabolism or absorption can better benefit from 5-methylTHF instead of FA. 5-MethylTHF [also known as (6S)-5-methylTHF] is the predominant natural form that is readily available for transport and metabolism. In contrast to FA, 5-methylTHF has no tolerable upper intake level and does not mask vitamin B12 deficiency. Supplementation of the natural form, 5-methylTHF, is a better alternative to supplementation of FA, especially in countries not applying a fortification program. Supplemental 5-methylTHF can effectively improve folate biomarkers in young women in early pregnancy in order to prevent NTDs.

  11. Insights into prevention of human neural tube defects by folic acid arising from consideration of mouse mutants.

    PubMed

    Harris, Muriel J

    2009-04-01

    Almost 30 years after the initial study by Richard W. Smithells and coworkers, it is still unknown how maternal periconceptional folic acid supplementation prevents human neural tube defects (NTDs). In this article, questions about human NTD prevention are considered in relation to three groups of mouse models: NTD mutants that respond to folate, NTD mutants and strains that do not respond to folate, and mutants involving folate-pathway genes. Of the 200 mouse NTD mutants, only a few have been tested with folate; half respond and half do not. Among responsive mutants, folic acid supplementation reduces exencephaly and/or spina bifida aperta frequency in the Sp(2H), Sp, Cd, Cited2, Cart1, and Gcn5 mutants. Prevention ranges from 35 to 85%. The responsive Sp(2H) (Pax3) mutant has abnormal folate metabolism, but the responsive Cited2 mutant does not. Neither folic nor folinic acid reduces NTD frequency in Axd, Grhl3, Fkbp8, Map3k4, or Nog mutants or in the curly tail or SELH/Bc strains. Spina bifida frequency is reduced in Axd by methionine and in curly tail by inositol. Exencephaly frequency is reduced in SELH/Bc by an alternative commercial ration. Mutations in folate-pathway genes do not cause NTDs, except for 30% exencephaly in folate-treated Folr1. Among folate-pathway mutants, neural tube closure is normal in Cbs, Folr2, Mthfd1, Mthfd2, Mthfr, and Shmt1 mutants. Embryos die by midgestation in Folr1, Mtr, Mtrr, and RFC1 mutants. The mouse models point to genetic heterogeneity in the ability to respond to folic acid and also to heterogeneity in genetic cause of NTDs that can be prevented by folic acid.

  12. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    NASA Astrophysics Data System (ADS)

    Elam, Fiona M.; Starostin, Sergey A.; Meshkova, Anna S.; van der Velden-Schuermans, Bernadette C. A. M.; van de Sanden, Mauritius C. M.; de Vries, Hindrik W.

    2017-06-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense ‘barrier layer’ and comparatively porous ‘buffer layer’ onto a flexible polyethylene 2,6 naphthalate substrate. For both layers, tetraethyl orthosilicate was used as the precursor gas, together with a mixture of nitrogen, oxygen and argon. The bilayer films demonstrated exceptionally low effective water vapour transmission rates in the region of 6.1  ×  10-4 g m-2 d-1 (at 40 °C, 90% relative humidity), thus capable of protecting flexible photovoltaics and thin film transistors from degradation caused by oxygen and water. The presence of the buffer layer within the bilayer architecture was mandatory in order to achieve the excellent encapsulation performance. Atomic force microscopy in addition to solvent permeation measurements, confirmed that the buffer layer prevented the formation of performance-limiting defects in the bilayer thin films, which likely occur as a result of excessive plasma-surface interactions during the deposition process. It emerged that the primary function of the buffer layer was therefore to act as a protective coating for the flexible polymer substrate material.

  13. Primary prevention of neural-tube defects and some other congenital abnormalities by folic acid and multivitamins: history, missed opportunity and tasks.

    PubMed

    Czeizel, Andrew E; Bártfai, Zoltán; Bánhidy, Ferenc

    2011-08-01

    The history of intervention trials of periconception folic acid with multivitamin and folic acid supplementation in women has shown a recent breakthrough in the primary prevention of structural birth defects, namely neural-tube defects and some other congenital abnormalities. Recently, some studies have demonstrated the efficacy of this new method in reducing congenital abnormalities with specific origin; for example, in the offspring of diabetic and epileptic mothers, and in pregnancy with high fever. The benefits and drawbacks of four possible uses of periconception folate/folic acid and multivitamin supplementation are discussed: we believe there has been a missed opportunity to implement this preventive approach in medical practice. The four methods are as follows: (i) dietary intake of folate and other vitamins, (ii) periconception folic acid/multivitamin supplementation, (iii) food fortification with folic acid, and (iv) the combination of oral contraceptives with 6S-5-methytetrahydrofolate ('folate').

  14. Primary prevention of neural-tube defects and some other congenital abnormalities by folic acid and multivitamins: history, missed opportunity and tasks

    PubMed Central

    Bártfai, Zoltán; Bánhidy, Ferenc

    2011-01-01

    The history of intervention trials of periconception folic acid with multivitamin and folic acid supplementation in women has shown a recent breakthrough in the primary prevention of structural birth defects, namely neural-tube defects and some other congenital abnormalities. Recently, some studies have demonstrated the efficacy of this new method in reducing congenital abnormalities with specific origin; for example, in the offspring of diabetic and epileptic mothers, and in pregnancy with high fever. The benefits and drawbacks of four possible uses of periconception folate/folic acid and multivitamin supplementation are discussed: we believe there has been a missed opportunity to implement this preventive approach in medical practice. The four methods are as follows: (i) dietary intake of folate and other vitamins, (ii) periconception folic acid/multivitamin supplementation, (iii) food fortification with folic acid, and (iv) the combination of oral contraceptives with 6S-5-methytetrahydrofolate (‘folate’). PMID:25083211

  15. Retinoblastoma protein prevents enteric nervous system defects and intestinal pseudo-obstruction

    PubMed Central

    Fu, Ming; Landreville, Solange; Agapova, Olga A.; Wiley, Luke A.; Shoykhet, Michael; Harbour, J. William; Heuckeroth, Robert O.

    2013-01-01

    The retinoblastoma 1 (RB1) tumor suppressor is a critical regulator of cell cycle progression and development. To investigate the role of RB1 in neural crest–derived melanocytes, we bred mice with a floxed Rb1 allele with mice expressing Cre from the tyrosinase (Tyr) promoter. TyrCre+;Rb1fl/fl mice exhibited no melanocyte defects but died unexpectedly early with intestinal obstruction, striking defects in the enteric nervous system (ENS), and abnormal intestinal motility. Cre-induced DNA recombination occurred in all enteric glia and most small bowel myenteric neurons, yet phenotypic effects of Rb1 loss were cell-type specific. Enteric glia were twice as abundant in mutant mice compared with those in control animals, while myenteric neuron number was normal. Most myenteric neurons also appeared normal in size, but NO-producing myenteric neurons developed very large nuclei as a result of DNA replication without cell division (i.e., endoreplication). Parallel studies in vitro found that exogenous NO and Rb1 shRNA increased ENS precursor DNA replication and nuclear size. The large, irregularly shaped nuclei in NO-producing neurons were remarkably similar to those in progeria, an early-onset aging disorder that has been linked to RB1 dysfunction. These findings reveal a role for RB1 in the ENS. PMID:24177421

  16. Prevention of valproic acid-induced neural tube defects by sildenafil citrate.

    PubMed

    Tiboni, Gian Mario; Ponzano, Adalisa

    2015-08-15

    This study was undertaken to test the effects of sildenafil citrate (SC), a type 5 phosphodiesterase inhibitor, on valproic acid (VPA)-induced teratogenesis. On gestation day (GD) 8, ICR (CD-1) mice were treated by gastric intubation with SC at 0 (vehicle), 1.0, 2.5, 5.0 or 10mg/kg. One hour later, animals received a teratogenic dose of VPA (600mg/kg) or vehicle. Developmental endpoints were evaluated near the end of gestation. Twenty-eighth percent of fetuses exposed to VPA had neural tube defects (exencephaly). Pretreatment with SC at 2.5, 5.0 or 10mg/kg significantly reduced the rate of VPA-induced exencephaly to 15.9%, 13.7%, and 10.0%, respectively. Axial skeletal defects were observed in 75.8% of VPA-exposed fetuses. Pre-treatment with SC at 10mg/kg, but not at lower doses, significantly decreased the rate of skeletally affected fetuses to 61.6%. These results show that SC, which prolongs nitric oxide (NO) signaling action protects from VPA-induced teratogenesis.

  17. Parents of Kids with Heart Defects Face PTSD Risk: Study

    MedlinePlus

    ... Feb. 1, 2017 (HealthDay News) -- Parents of children born with serious heart defects may be at high risk for post-traumatic stress disorder (PTSD) and other mental health problems, a new study suggests. PTSD refers to anxiety and fear ...

  18. Studying defects in the silicon lattice using CCDs

    NASA Astrophysics Data System (ADS)

    Hall, D. J.; Murray, N. J.; Gow, J. P. D.; Wood, D.; Holland, A.

    2014-12-01

    on techniques which analyse the average properties of many traps, often over several trap species. Here is presented a selection of methods, both experimental and simulated, that can be used to begin to study populations of lattice defects down to individual defects themselves. These studies have enabled the investigation of not only the defect densities and the device-averaged trap parameters, but also the properties of individual lattice defects in the device, en route to actively predicting the impact of the radiation environment before launch.

  19. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid.

    PubMed

    Heseker, Helmut B; Mason, Joel B; Selhub, Jacob; Rosenberg, Irwin H; Jacques, Paul F

    2009-07-01

    Some countries have introduced mandatory folic acid fortification, whereas others support periconceptional supplementation of women in childbearing age. Several European countries are considering whether to adopt a fortification policy. Projections of the possible beneficial effects of increased folic acid intake assume that the measure will result in a considerable reduction in neural-tube defects (NTD) in the target population. Therefore, the objective of the present study is to evaluate the beneficial effects of different levels of folic acid administration on the prevalence of NTD. Countries with mandatory fortification achieved a significant increase in folate intake and a significant decline in the prevalence of NTD. This was also true for supplementation trials. However, the prevalence of NTD at birth declined to approximately five cases at birth per 10 000 births and seven to eight cases at birth or abortion per 10 000 births. This decline was independent of the amount of folic acid administered and apparently reveals a 'floor effect' for folic acid-preventable NTD. This clearly shows that not all cases of NTD are preventable by increasing the folate intake. The relative decline depends on the initial NTD rate. Countries with NTD prevalence close to the observed floor may have much smaller reductions in NTD rates with folic acid fortification. Additionally, potential adverse effects of fortification on other vulnerable population groups have to be seriously considered. Policy decisions concerning national mandatory fortification programmes must take into account realistically projected benefits as well as the evidence of risks to all vulnerable groups.

  20. Treatment of Bone Defects in War Wounds: Retrospective Study

    PubMed Central

    Grubor, Predrag; Milicevic, Snjezana; Grubor, Milan; Meccariello, Luigi

    2015-01-01

    Introduction: Results of the treatment of open fractures primarily depend on the treatment of connected soft tissue injuries. Objective: The aim was to present the experience and methods gained during the treatment of diaphyseal bone defects as a consequence of gunshot fracture soft war trauma. Patients and Methods: The study consisted of 116 patients with the diaphyseal bone defect who were treated with the usage of primary and delayed autotransplantation of bones, transplants of the fibula and Ilizarov distraction osteogenesis. Results: The results of compensation of bone defect less than 4 cm and conducted by an early cortico-spongioplastics were as follows: good in 8 respondents (45%), satisfactory in 6 (34%) and poor in 4 respondents (21%). In cases of delayed cortico-spongioplastics, the above mentioned results were: good in 36 (41%) respondents, satisfactory in 24 (34%) and poor in 16 (25%) respondents. The results of compensation of bone defect greater than 4 cm with the usage of fibular transplant were as follows: good in 3 (38%) respondents, satisfactory in 3 (38%) and poor in 2 (24%), and with the usage of using the Ilizarov method, the results were as follows: good in 8 (57%) respondents, satisfactory in 3 (21.5%) and poor in 3(21.5%) respondents. Conclusion: The results showed that, in cases of compensation of bone defects less than 4 cm, the advantage is given to the primary spongioplastics over the delayed one. In cases of compensation of bone defects greater than 4 cm, the advantage is given to the Ilizarov distraction osteogenesis when compared to the fibular transplant. PMID:26543315

  1. The preventive effects of taurine on neural tube defects through the Wnt/PCP-Jnk-dependent pathway.

    PubMed

    Zhang, Qinghua; Liu, Yang; Wang, Hui; Ma, Li; Xia, Hechun; Niu, Jianguo; Sun, Tao; Zhang, Li

    2017-07-17

    The aim of this study was to clarify the protective role of taurine in neuronal apoptosis and the role of the Wnt/PCP-Jnk pathway in mediating the preventive effects of taurine on neural tube defects (NTDs). HT-22 cells (a hippocampal neuron cell line) were divided into a control group, a glutamate-induced apoptosis group, and glutamate (4.0 mmol/L) plus low-dose taurine (L; 0.5 mmol/L) and high-dose taurine (H; 2.0 mmol/L) groups. The MTT assay was used to monitor cell proliferation and cell survival. Immunofluorescence and Western blot analyses were used to determine caspase 9 expression. Retinoic acid (RA) induced embryonic NTDs in Kunming mice, thus establishing an NTD model. Pregnant mice were divided into a control group, an RA (30 mg/kg body weight) group, and an RA (30 mg/kg body weight) plus taurine (free drinking of 2 g/L solution) group. Immunohistochemistry and Western blot analyses were used to detect the expression of Dvl, RhoA and phosphorylated (p)-Jnk/Jnk in the embryonic neural tubes. In HT-22 cells, the apoptosis rate was significantly higher and caspase 9 activation was also significantly increased in the glutamate-induced apoptosis group compared to the L and H taurine groups. In the NTD model, the expression levels of Dvl, RhoA, and p-Jnk were significantly higher in the RA group than in the control group, whereas they were significantly reduced in the RA + taurine group. This study suggests that taurine has positive effects on neuronal protection and NTD prevention. Moreover, the Wnt/PCP-Jnk-dependent pathway plays an important role in taurine-mediated prevention of NTDs.

  2. Magnitude of Birth Defects in Central and Northwest Ethiopia from 2010-2014: A Descriptive Retrospective Study

    PubMed Central

    Taye, Molla; Afework, Mekbeb; Fantaye, Wondwossen; Diro, Ermias; Worku, Alemayehu

    2016-01-01

    Background Birth defects are defined as structural and functional defects that develop during the organogenesis period and present at birth or detected later in life. They are one of the leading causes of infant and child mortality, morbidity, and long term disability. The magnitude of birth defects varies from country to country and from race/ethnicity to race/ethnicity, and about 40–60% of their causes are unknown. The known causes of birth defects are genetic and environmental factors which may be prevented. For various reasons, there is lack of data and research on birth defects in Ethiopia. Objective The major objective of this study is to estimate the magnitude of birth defects in Ethiopia. Subject and Methods A hospital based, retrospective, cross sectional, descriptive study was conducted. The subjects were babies/children aged 0–17years who visited selected hospitals between 2010 and 2014. Fourteen hospitals (8 in Addis Ababa, 6 in Amhara Region) were selected purposively based on case load. A data retrieving form was developed to extract relevant information from record books. Results In the hospitals mentioned, 319,776 various medical records of children aged 0–17years were found. Of these, 6,076 (1.9% with 95% CI: 1.85%–1.95%) children were diagnosed as having birth defects. The majority (58.5%) of the children were male and 41.5% female. A slightly more than half (51.1%) of the children were urban dwellers, while 48.9% were from rural areas. Among the participants of the study the proportion of birth defects ranged as follows: orofacial (34.2%), neural tube (30.8%), upper and lower limb (12.8%), cardiovascular system (10.3%), digestive system and abdominal wall (4.8%), unspecified congenital malformations (2.5%), Down syndrome (2%), genitourinary system (2%), head, face, and neck defects (0.4%), and others (0.3%). The trend of birth defects increased linearly over time [Extended Mantel-Haenszel chi square for linear trend = 356.7 (P<0

  3. Preventing solidification defects in large superalloy castings used in advanced electric power systems

    NASA Astrophysics Data System (ADS)

    Valdes Ortiz, Jairo Antonio

    The need for clean and affordable power has resulted in great demand for high-efficiency gas turbine power systems. To improve energy generation efficiency, and lower CO2 emissions, the new generation of land based gas turbines needs to be larger and operated at a higher temperature. Consequently, it is required the use of Nb-containing superalloys such as Inconel 718 for the rotor disk, to avoid overaging of the microstructure during the forging process, but its applicability is being limited by difficulties in the reliable production of large Vacuum Arc Remelting (VAR) ingots (33 to ˜35 in. diameter) without macrosegregation defects such as freckles and center segregation. These defects impair the mechanical properties of the material and are believed to be caused by convection in the mush layer. Because they cannot be corrected by subsequent treatment, the affected ingots should be scrapped highly increasing the production costs. In this work, the aim was to take steps toward the final goal of preventing macrosegregation defects in VAR ingots by assessing the need for accurate determination of the driving force related to the solutal buoyancy in the mushy layer and postulating a criterion for freckling prediction that could better resolve if freckles will or will not evolve under certain processing conditions. An experimental methodology was proposed to determine the partition coefficients of the major solute elements and better agreement was obtained with the predictions made with the newly developed databases, suggesting that improvements in the accuracy of the theoretical predictions can still be obtained and are necessary for freckling prediction. Quenching modified DTA (MDTA) tests were proven to be suited for measuring the partition coefficients of the solute elements, and it was assumed successfully that the cooling rate prior to the quenching step of 0.083 Ks-1 was slow enough to permit easy quenching, while being sufficiently fast for the primary

  4. A real-space study of random extended defects in solids: Application to disordered Stone-Wales defects in graphene

    NASA Astrophysics Data System (ADS)

    Chowdhury, Suman; Baidya, Santu; Nafday, Dhani; Halder, Soumyajyoti; Kabir, Mukul; Sanyal, Biplab; Saha-Dasgupta, Tanusri; Jana, Debnarayan; Mookerjee, Abhijit

    2014-07-01

    We propose here a first-principles, parameter free, real space method for the study of disordered extended defects in solids. We shall illustrate the power of the technique with an application to graphene sheets with randomly placed Stone-Wales defects and shall examine the signature of such random defects on the density of states as a function of their concentration. The technique is general enough to be applied to a whole class of systems with lattice translational symmetry broken not only locally but by extended defects and defect clusters. The real space approach will allow us to distinguish signatures of specific defects and defect clusters. The authors go on to remark that although this disorder may not affect the vibrational spectrum significantly, the electronic structure obtained from a periodic array of SW defects needs to be interpreted with care. Our real space recursion approach [41] makes no appeal to lattice translational symmetry and is thus ideal for studying topological disorder and its effect on electronic structure. The illustration of this point is the justification of our proposed methodology and the main focus of this communication.

  5. Ab-intitio Studies of Defects in Ferroelectrics

    NASA Astrophysics Data System (ADS)

    Poykko, Sami

    2000-03-01

    Defects, defect complexes and domain walls in PbTiO3 have been studied using a first-principles method. Platinum is a widely used electrode material for PZT. Due to relatively high deposition temperatures a large concentration of Pt atoms diffuse into PZT, where they occupy Ti-sites and act as acceptors. Platinum impurity is shown to form a tightly bond pair with oxygen vacancy. This complex can have a significant role in fatigue, since each of these strongly polar defect also pin a polarization of a surrounding lattice. This result implies that in order to increase fatigue resistance of PZT it is extremely important to minimize especially acceptor type impurities [1]. We have shown that oxygen and lead vacancies do not form strongly bound defect complexes in PZT and therefore their creation does not seem to be directly involved in fatigue or imprint. According to our calculations a formation of a oxygen-vacancy lead-vacancy pair (close or distant) becomes exothermic under certain conditions. Therefore large number of vacancies are produced to PZT leading to resistance degradation and overall crystal quality also becomes worse [2]. An 180 degree domain wall has been shown to have an energy density of 150 erg/cm^2 and is lead-centered (ie. symmetry plane goes along Pb-atoms). A minimum width of a domain is calculated to be 4 lattice constants, narrower domains are found to be thermodynamically unstable [3]. footnote[1]S. Poykko and D. J. Chadi, "Dipolar Defect Model for Fatigue in Ferroelectric Perovskites" Physical Review Letters 83, 1231 (1999). footnote[2]S. Poykko and D. J. Chadi, "First principles study of Pb-vacancies in PbTiO_3", Applied Physics Letters, in print (2000). footnote[3]S. Poykko and D. J. Chadi, "Ab initio study of 180 degree domain wall energy and structure in PbTiO_3" Applied Physics Letters, 75, 2830 (1999).

  6. Effects of folic acid supplementation during different pregnancy periods and relationship with the other primary prevention measures to neural tube defects.

    PubMed

    Gong, Rui; Wang, Zhi-Ping; Wang, Meng; Gao, Li-Jie; Zhao, Zhong-Tang

    2016-12-01

    To find out the prevention effects of folic acid supplements during different pregnancy periods on neural tube defects (NTDs) and the relationship of folic acid supplements with the other NTDs' primary preventive measures. A 1:1 case-control study was conducted. Four hundred and fifty-nine women who delivered or gestate infants/fetuses with NTDs in the last two years were randomly selected as cases and were matched with women who delivered babies without obvious birth defects as controls. For anencephaly, folic acid supplementation during the periconceptional period and preconceptional period has a 57-83% reduction in risk of NTDs(ORs ranged from 0.17 to 0.43). For spina bifida, folic acid supplementation during the periconceptional period has a 79% reduction in risk of NTDs (OR = 0.21). For encephalocele, folic acid supplementation during the periconceptional period has a 67% reduction in risk of NTDs (OR = 0.33). The prevention effects on NTDs were significant when these preventive measures combined with folic acid supplements during the periconceptional period, with OR 0.04, 0.07, 0.10 and 0.11. The specific effects of folic acid supplementation during different periods show the reduction in the risk of NTDs, anencephaly, spina bifida, encephalocele. During periconceptional period, folic acid supplements have preventive effects on all NTDs' subtypes.

  7. Synaptic defects associated with s-inclusion body myositis are prevented by copper.

    PubMed

    Aldunate, R; Minniti, A N; Rebolledo, D; Inestrosa, N C

    2012-08-01

    Sporadic-inclusion body myositis (s-IBM) is the most common skeletal muscle disorder to afflict the elderly, and is clinically characterized by skeletal muscle degeneration. Its progressive course leads to muscle weakness and wasting, resulting in severe disability. The exact pathogenesis of this disease is unknown and no effective treatment has yet been found. An intriguing aspect of s-IBM is that it shares several molecular abnormalities with Alzheimer's disease, including the accumulation of amyloid-β-peptide (Aβ). Both disorders affect homeostasis of the cytotoxic fragment Aβ(1-42) during aging, but they are clinically distinct diseases. The use of animals that mimic some characteristics of a disease has become important in the search to elucidate the molecular mechanisms underlying the pathogenesis. With the aim of analyzing Aβ-induced pathology and evaluating the consequences of modulating Aβ aggregation, we used Caenorhabditis elegans that express the Aβ human peptide in muscle cells as a model of s-IBM. Previous studies indicate that copper treatment increases the number and size of amyloid deposits in muscle cells, and is able to ameliorate the motility impairments in Aβ transgenic C. elegans. Our recent studies show that neuromuscular synaptic transmission is defective in animals that express the Aβ-peptide and suggest a specific defect at the nicotine acetylcholine receptors level. Biochemical analyses show that copper treatment increases the number of amyloid deposits but decreases Aβ-oligomers. Copper treatment improves motility, synaptic structure and function. Our results suggest that Aβ-oligomers are the toxic Aβ species that trigger neuromuscular junction dysfunction.

  8. Ab initio study of tungsten defects near the surface

    NASA Astrophysics Data System (ADS)

    Guerrero, C. L.; Gordillo, N.; Iglesias, R.; Perlado, J. M.; Gonzalez, C.

    2016-05-01

    A first principles analysis of the behaviour of point defects, namely, self-interstitial atoms, a single vacancy and light impurity atoms such as H and He in tungsten is reported. These defects can be produced in the first wall of the future nuclear fusion reactors due to the high radiation fluxes present. The evolution of defects that appear in the bulk and end up reaching the surface has been followed. An energetic study has been combined with a detailed charge density analysis of the system by means of the SIESTA code. The resulting data have been validated by confronting them with those obtained with a more precise plane wave code, namely VASP. Meanwhile, the structural and the mechanical properties of the system have been positively compared with experimental measurements. Such comparisons have led us to present a new SIESTA basis for tungsten. This complete analysis establishes a nanoscopic view of the phenomena involving the presence of light atoms at native defects in tungsten, paying special attention to the vicinity of surfaces.

  9. Calculation studies on point defects in perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Han, Dan; Dai, Chenmin; Chen, Shiyou

    2017-01-01

    The close-to-optimal band gap, large absorption coefficient, low manufacturing cost and rapid increase in power conversion efficiency make the organic-inorganic hybrid halide (CH3NH3PbI3) and related perovskite solar cells very promising for commercialization. The properties of point defects in the absorber layer semiconductors have important influence on the photovoltaic performance of solar cells, so the investigation on the defect properties in the perovskite semiconductors is necessary for the optimization of their photovoltaic performance. In this work, we give a brief review to the first-principles calculation studies on the defect properties in a series of perovskite semiconductors, including the organic-inorganic hybrid perovskites and inorganic halide perovskites. Experimental identification of these point defects and characterization of their properties are called for. Project supported by the National Natural Science Foundation of China (No. 61574059), the Shanghai Rising-Star Program (No. 14QA1401500), the Shu-Guang Program (15SG20), and the CC of ECNU.

  10. A biomechanical study of periacetabular defects and cement filling.

    PubMed

    Li, Zuoping; Butala, Neha B; Etheridge, Brandon S; Siegel, Herrick J; Lemons, Jack E; Eberhardt, Alan W

    2007-04-01

    Periacetabular bone metastases cause severe pain and functional disability in cancer patients. Percutaneous acetabuloplasty (PCA) is a minimally invasive, image-guided procedure whereby cement is injected into lesion sites. Pain relief and functional restoration have been observed clinically; however, neither the biomechanical consequences of the lesions nor the effectiveness of the PCA technique are well understood. The objective of this study was to investigate how periacetabular lesion size, cortex involvement, and cement modulus affect pelvic bone stresses and strains under single-legged stance loading. Experiments were performed on a male cadaver pelvis under conditions of intact, periacetabular defect, and cement-filling with surface strains recorded at three strain gage locations. The experimental data were then employed to validate three-dimensional finite element models of the same pelvis, developed using computed tomography data. The models demonstrated that increases in cortical stresses were highest along the posterior column of the acetabulum, adjacent to the defect. Cortical stresses were more profoundly affected in the presence of transcortical defects, as compared to those involving only trabecular bone. Cement filling with a modulus of 2.2 GPa was shown to restore cortical stresses to near intact values, while a decrease in cement modulus due to inclusion of BaSO(4) reduced the restorative effect. Peak acetabular contact pressures increased less than 15% for all simulated defect conditions; however, the contact stresses were reduced to levels below intact in the presence of either cement filling. These results suggest that periacetabular defects may increase the vulnerability of the pelvis to fracture depending on size and cortical involvement and that PCA filling may lower the risk of periacetabular fractures.

  11. First-principles study of point defects in thorium carbide

    NASA Astrophysics Data System (ADS)

    Pérez Daroca, D.; Jaroszewicz, S.; Llois, A. M.; Mosca, H. O.

    2014-11-01

    Thorium-based materials are currently being investigated in relation with their potential utilization in Generation-IV reactors as nuclear fuels. One of the most important issues to be studied is their behavior under irradiation. A first approach to this goal is the study of point defects. By means of first-principles calculations within the framework of density functional theory, we study the stability and formation energies of vacancies, interstitials and Frenkel pairs in thorium carbide. We find that C isolated vacancies are the most likely defects, while C interstitials are energetically favored as compared to Th ones. These kind of results for ThC, to the best authors' knowledge, have not been obtained previously, neither experimentally, nor theoretically. For this reason, we compare with results on other compounds with the same NaCl-type structure.

  12. Defect metastability in surfaces: A study of EL2 defect in GaAs(110)

    SciTech Connect

    Zhang, S.B.

    1999-08-01

    Although it has been widely accepted that EL2 in GaAs is an As antisite, the identity of the metastable state of EL2thinsp(=EL2{sup {asterisk}}) has not been confirmed by experiment. Here it is suggested that cross-sectional scanning tunneling microscopy may be used to identify EL2{sup {asterisk}}. My suggestion is based on a comprehensive first-principles total energy study of surface defect metastability. It reveals rich structures of the EL2{sup {asterisk}} near the surface. The energy difference between EL2{sup {asterisk}} and EL2 can be reduced to only a tenth of that bulk due to interaction with relaxed surface atoms. {copyright} {ital 1999} {ital The American Physical Society}

  13. Use of Family History Information for Neural Tube Defect Prevention: Integration into State-Based Recurrence Prevention Programs

    ERIC Educational Resources Information Center

    Green, Ridgely Fisk; Ehrhardt, Joan; Ruttenber, Margaret F.; Olney, Richard S.

    2011-01-01

    A family history of neural tube defects (NTDs) can increase the risk of a pregnancy affected by an NTD. Periconceptional folic acid use decreases this risk. Purpose: Our objective was to determine whether second-degree relatives of NTD-affected children showed differences in folic acid use compared with the general population and to provide them…

  14. Pollution Prevention Wipe Application Study

    SciTech Connect

    Lopez, E.P.; Modderman, W.E.; Montoya, M.G.

    1999-02-10

    As part of a pollution prevention program, a study was conducted at Sandia National Laboratories and at the Amarillo, ''Pantex Plant'' to identify a suitable replacement solvent(s) for cleaning hardware during routine maintenance operations. Current cleaning is performed using solvents (e.g. acetone, toluene, MEK, alcohols) that are classified as Resource Conservation and Recovery Act (RCW) materials. The Environmental Protection Agency (EPA) has assigned four characteristics as the criteria for determining whether a material is identified as hazardous under RCRA: Ignitability, Corrosivity, Reactivity and Toxicity. Within the DOE and DoD sector, these solvents are used with hand wipes to clean surfaces prior to O-ring replacement, to remove decals for new labeling, to clean painted surfaces prior to reconditioning, and for other general maintenance purposes. In some cases, low level radioactive contamination during cleaning necessitates that the RCIL4 solvent-containing wipes be classified as mixed waste. To avoid using RCRA materials, cleaning candidates were sought that had a flashpoint greater than 140 F, a pH between 2.5 and 12.5, and did not fail the reactivity and toxicity criteria. Three brominated cleaners, two hydrofluoroether azeotropes and two aliphatic hydrocarbon cleaner formulations were studied as potential replacements. Cleaning efficacy, materials compatibility, corrosion and accelerated aging studies were conducted and used to screen potential candidates. Hypersolve NPB (an n-propyl bromide based formulation) consistently ranked high in removing typical contaminants for weapons applications.

  15. Evaluation and Visualization of Surface Defects — a Numerical and Experimental Study on Sheet-Metal Parts

    NASA Astrophysics Data System (ADS)

    Andersson, A.

    2005-08-01

    The ability to predict surface defects in outer panels is of vital importance in the automotive industry, especially for brands in the premium car segment. Today, measures to prevent these defects can not be taken until a test part has been manufactured, which requires a great deal of time and expense. The decision as to whether a certain surface is of acceptable quality or not is based on subjective evaluation. It is quite possible to detect a defect by measurement, but it is not possible to correlate measured defects and the subjective evaluation. If all results could be based on the same criteria, it would be possible to compare a surface by both FE simulations, experiments and subjective evaluation with the same result. In order to find a solution concerning the prediction of surface defects, a laboratory tool was manufactured and analysed both experimentally and numerically. The tool represents the area around a fuel filler lid and the aim was to recreate surface defects, so-called "teddy bear ears". A major problem with the evaluation of such defects is that the panels are evaluated manually and to a great extent subjectivity is involved in the classification and judgement of the defects. In this study the same computer software was used for the evaluation of both the experimental and the numerical results. In this software the surface defects were indicated by a change in the curvature of the panel. The results showed good agreement between numerical and experimental results. Furthermore, the evaluation software gave a good indication of the appearance of the surface defects compared to an analysis done in existing tools for surface quality measurements. Since the agreement between numerical and experimental results was good, this indicates that these tools can be used for an early verification of surface defects in outer panels.

  16. Awareness and intake of folic acid for the prevention of neural tube defects among Lebanese women of childbearing age.

    PubMed

    Nasr Hage, Claudine; Jalloul, Maya; Sabbah, Mohamad; Adib, Salim M

    2012-01-01

    Since the early 1990s, international recommendations have promoted folic acid supplementation during the periconception period as an effective way of preventing neural tube defects (NTDs). However, the adoption of this recommendation remains insufficient. To assess the awareness and actual intake of folic acid among married Lebanese women aged 18-45 years, a cross-sectional study was conducted among 600 women selected from all five administrative districts in Lebanon, using a multistage cluster sampling procedure. An anonymous questionnaire was completed which covered measures of knowledge and use of folate supplements, as well as demographic, socioeconomic and obstetrical factors. Sixty percent of surveyed women (60%; n = 360) had heard about folic acid. Doctors were the most frequent source of information (61.1%) but only 24.7% of women have been told of the correct period during which folic acid supplementation was useful. Overall, only 6.2% had taken folic acid tablets during the adequate period. Younger age, higher education level and stability/sufficiency of income appeared to be significant predictors of awareness among Lebanese women. Actual folic acid intake was significantly associated with younger age, higher number of pregnancies, planning the last pregnancy and having had that last one after 1990. In Lebanon, the level of folic acid awareness and adequate intake remain relatively low. Several approaches should be used to promote folic acid intake including awareness campaigns, and routine counseling by primary health care physicians on folic acid during preconception visits.

  17. [Attitudes of pregnant Japanese women and folic acid intake for the prevention of neural tube defects: a nationwide Internet survey].

    PubMed

    Sato, Yoko; Nakanishi, Tomoko; Chiba, Tsuyoshi; Umegaki, Keizo

    2014-01-01

    Folic acid intake is recommended for pregnant women because it significantly reduces the risk of neural tube defects (NTD) in the fetus. However, the risk of NTD remains medium in Japan. In this study, the attitudes of pregnant Japanese women and factors related to folic acid intake for the prevention of NTD were evaluated using a nationwide survey. An Internet-based questionnaire was conducted on 2,367 pregnant Japanese women who were registrants of a Japanese social research company in January 2012; 1,236 of these women responded. In the questionnaires, the knowledge regarding the folate intake (i.e., name of folic acid, the risk of NTD, recommended doses, and timing), actual intake of folic acid, demographic factors (i.e., age, geographical area, gestational age, and birth order), and intake of dietary supplements were surveyed. Eighty-five percent of respondents consumed folate, which was mostly obtained through dietary folic acid supplements during the first month of pregnancy or after. Factors associated with loss of folic acid intake until 3 months of pregnancy included lack of knowledge, failure to consume dietary supplements, younger age, and multigravida. Many pregnant women in Japan consumed folic acid. However, most of them started supplementation after pregnancy recognition, which is too late to reduce the risk of NTD. Alternative strategies to increase the efficacy of folic acid intake, such as recommending folic acid-enriched foods, promoting folic acid fortification efforts, and providing access to practical information, are necessary.

  18. C5a receptor signaling prevents folate deficiency-induced neural tube defects in mice.

    PubMed

    Denny, Kerina J; Coulthard, Liam G; Jeanes, Angela; Lisgo, Steven; Simmons, David G; Callaway, Leonie K; Wlodarczyk, Bogdan; Finnell, Richard H; Woodruff, Trent M; Taylor, Stephen M

    2013-04-01

    The complement system is involved in a range of diverse developmental processes, including cell survival, growth, differentiation, and regeneration. However, little is known about the role of complement in embryogenesis. In this study, we demonstrate a novel role for the canonical complement 5a receptor (C5aR) in the development of the mammalian neural tube under conditions of maternal dietary folic acid deficiency. Specifically, we found C5aR and C5 to be expressed throughout the period of neurulation in wild-type mice and localized the expression to the cephalic regions of the developing neural tube. C5aR was also found to be expressed in the neuroepithelium of early human embryos. Ablation of the C5ar1 gene or the administration of a specific C5aR peptide antagonist to folic acid-deficient pregnant mice resulted in a high prevalence of severe anterior neural tube defect-associated congenital malformations. These findings provide a new and compelling insight into the role of the complement system during mammalian embryonic development.

  19. Study of point defects in alkaline-earth sulfides

    SciTech Connect

    Pandey, R.; Kunz, A.B.; Vail, J.M.

    1988-11-01

    The results of a computer simulation study of point defects including vacancy, interstitial, and F/sup +/ center in alkaline-earth sulfides are presented. The study is based on ICECAP/HADES simulation procedures and uses empirical interionic potentials obtained from the analysis of macroscopic data for these materials. The results predict the dominance of Schottky disorder and suggest that vacancy migration predominates in alkaline-earth sulfides. Furthermore, the calculated F/sup +/ center absorption energy is in good agreement with the experimental data deduced from the optical stimulated studies in these materials.

  20. Ab initio studies of niobium defects in uranium

    SciTech Connect

    Xiang, S; Huang, H; Hsiung, L

    2007-06-01

    Uranium (U), with the addition of small amount of niobium (Nb), is stainless. The Nb is fully miscible with the high temperature phase of U and tends to segregate upon cooling below 647 C. The starting point of segregation is the configuration of Nb substitutional or interstitial defects. Using density-functional-theory based ab initio calculations, the authors find that the formation energy of a single vacancy is 1.08 eV, that of Nb substitution is 0.59 eV, that of Nb interstitial at octahedral site is 1.58 eV, and that of Nb interstitial at tetrahedral site is 2.35 eV; all with reference to a reservoir of {gamma} phase U and pure Nb. The formation energy of Nb defects correlates with the local perturbation of electron distribution; higher formation energy to larger perturbation. Based on this study, Nb atoms thermodynamically prefer to occupy substitutional sites in {gamma} phase U, and they prefer to be in individual substitutional defects than clusters.

  1. Lower rate of selected congenital heart defects with better maternal diet quality: a population-based study.

    PubMed

    Botto, Lorenzo D; Krikov, Sergey; Carmichael, Suzan L; Munger, Ronald G; Shaw, Gary M; Feldkamp, Marcia L

    2016-01-01

    To evaluate whether better diet quality in mothers is associated with lower risk for major non-syndromic congenital heart defects in their children. Multicentre population-based case-control study, the National Birth Defects Prevention Study. Ten sites in the USA. Mothers of babies with major non-syndromic congenital heart defects (n=9885) and mothers with unaffected babies (n=9468) with estimated date of delivery from 1997 to 2009. Adjusted ORs for specific major congenital heart defects by quartiles of maternal diet quality in the year before pregnancy, assessed by the Diet Quality Index for pregnancy (DQI-P) and the Mediterranean Diet Score. Quartile 1 (Q1) reflecting the worst diet quality and Q4 the best diet quality. Better diet quality was associated with reduced risk for some conotruncal and atrial septal heart defects. For DQI-P, estimated risks reductions (Q4 vs Q1) for conotruncal defects were 37% for tetralogy of Fallot (OR 0.63, 95% CI 0.49 to 0.80) and 24% overall (OR 0.76, 95% CI 0.64 to 0.91); and for septal defects, 23% for atrial septal defects (OR 0.77, 95% CI 0.63 to 0.94) and 14% overall (OR 0.86, 95% CI 0.75 to 1.00). Risk reductions were weaker or minimal for most other major congenital heart defects. Better diet quality is associated with a reduced occurrence of some conotruncal and septal heart defects. This finding suggests that a reduction in certain cardiac malformations may be an additional benefit of improved maternal diet quality, reinforcing current preconception care recommendations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  2. Optimal serum and red blood cell folate concentrations in women of reproductive age for prevention of neural tube defects: World Health Organization guidelines.

    PubMed

    Cordero, Amy M; Crider, Krista S; Rogers, Lisa M; Cannon, Michael J; Berry, R J

    2015-04-24

    Neural tube defects (NTDs) such as spina bifida, anencephaly, and encephalocele are serious birth defects of the brain and spine that occur during the first month of pregnancy when the neural tube fails to close completely. Randomized controlled trials and observational studies have shown that adequate daily consumption of folic acid before and during early pregnancy considerably reduces the risk for NTDs. The U.S. Public Health Service recommends that women capable of becoming pregnant consume 400 µg of folic acid daily for NTD prevention. Furthermore, fortification of staple foods (e.g., wheat flour) with folic acid has decreased folate-sensitive NTD prevalence in multiple settings and is a highly cost-effective intervention.

  3. Extended defect study in Si: EBIC versus LBIC

    NASA Astrophysics Data System (ADS)

    Orlov, V. I.; Yakimov, E. B.

    2016-11-01

    A comparative study of multicrystalline Si and plastically deformed single crystalline Si by the electron (EBIC) and laser beam induced current (LBIC) methods has been carried out. It is shown that the LBIC contrast of two-dimensional defects in crystals with large diffusion length can be a few times higher than that in the EBIC method. Thus, in recent Si structures the LBIC method allows to reveal grain boundaries with the lower recombination velocity than the EBIC on. The advantages of LBIC for the dislocation trail study in Si and for backside metallization effects in solar cells are demonstrated.

  4. 10 Projects for Preventing Fetal Alcohol Syndrome and Other Alcohol-Related Birth Defects and Have You Heard about Alcohol and Pregnancy.

    ERIC Educational Resources Information Center

    Adams, Jerry; And Others

    A set of two pamphlets is presented on the topic of Fetal Alcohol Syndrome and Alcohol-Related Birth Defects. "Ten Projects for Preventing Fetal Alcohol Syndrome and Other Alcohol-Related Birth Defects" provides ideas and materials for students and others to use in educating the public about the dangers of alcohol use during pregnancy.…

  5. 10 Projects for Preventing Fetal Alcohol Syndrome and Other Alcohol-Related Birth Defects and Have You Heard about Alcohol and Pregnancy.

    ERIC Educational Resources Information Center

    Adams, Jerry; And Others

    A set of two pamphlets is presented on the topic of Fetal Alcohol Syndrome and Alcohol-Related Birth Defects. "Ten Projects for Preventing Fetal Alcohol Syndrome and Other Alcohol-Related Birth Defects" provides ideas and materials for students and others to use in educating the public about the dangers of alcohol use during pregnancy.…

  6. Functional studies on three novel HCNH2 mutations in Taiwan: Identification of distinct mechanisms of channel defect and dissociation between glycosylation defect and assembly defect

    SciTech Connect

    Hsueh, C.-H.; Chen, W.-P.; Lin, J.-L.; Liu, Y.-B.; Su, M.-J.; Lai, L.-P.

    2008-09-05

    Mutations of the KCNH2 with decreased channel activity lead to congenital long QT syndrome (LQTS). We studied the electrophysiological, glycosylation, trafficking and assembly properties of three novel KCNH2 mutations identified in Taiwanese patients with LQTS (p.N633D, p.R744fs, and p.P923fs). When expressed in HEK293T cells, p.N633D and p.R744fs HERG channels displayed no HERG current while p.P923fs HERG channel showed HERG current with significantly lower (34%) current density and faster inactivation kinetics. In Western blot analysis, pR744fs was the only one with glycosylation defect, which was in consistence with the confocal microscopic findings showing that p.R744fs-GFP was the only one with trafficking defect. However, p.R744fs-GFP differed from pR744fs in being fully glycosylated while p.R744fs fusion with GFP at the N-terminus revealed glycosylation defect. To access the assembly capacity of each mutant, co-immunoprecipitation was conducted. Wild type (WT), p.N633D, and p.P923fs HERG protein showed assembly ability while p.R744fs failed to assemble with neither WT nor itself. In conclusion, we identified three novel LQTS-related KCNH2 mutations and each had a distinct mechanism of channel defect. For p.R744fs mutant, adding GFP to the C-terminus rescued the glycosylation defect but the channel was still assembly defective indicating a dissociation between glycosylation and assembly defects.

  7. Functional studies on three novel HCNH2 mutations in Taiwan: identification of distinct mechanisms of channel defect and dissociation between glycosylation defect and assembly defect.

    PubMed

    Hsueh, Chia-Hsiang; Chen, Wen-Pin; Lin, Jiunn-Lee; Liu, Yen-Bin; Su, Ming-Jai; Lai, Ling-Ping

    2008-09-05

    Mutations of the KCNH2 with decreased channel activity lead to congenital long QT syndrome (LQTS). We studied the electrophysiological, glycosylation, trafficking and assembly properties of three novel KCNH2 mutations identified in Taiwanese patients with LQTS (p.N633D, p.R744fs, and p.P923fs). When expressed in HEK293T cells, p.N633D and p.R744fs HERG channels displayed no HERG current while p.P923fs HERG channel showed HERG current with significantly lower (34%) current density and faster inactivation kinetics. In Western blot analysis, pR744fs was the only one with glycosylation defect, which was in consistence with the confocal microscopic findings showing that p.R744fs-GFP was the only one with trafficking defect. However, p.R744fs-GFP differed from pR744fs in being fully glycosylated while p.R744fs fusion with GFP at the N-terminus revealed glycosylation defect. To access the assembly capacity of each mutant, co-immunoprecipitation was conducted. Wild type (WT), p.N633D, and p.P923fs HERG protein showed assembly ability while p.R744fs failed to assemble with neither WT nor itself. In conclusion, we identified three novel LQTS-related KCNH2 mutations and each had a distinct mechanism of channel defect. For p.R744fs mutant, adding GFP to the C-terminus rescued the glycosylation defect but the channel was still assembly defective indicating a dissociation between glycosylation and assembly defects.

  8. Thermal buckling behavior of defective CNTs under pre-load: A molecular dynamics study.

    PubMed

    Mehralian, Fahimeh; Tadi Beni, Yaghoub; Kiani, Yaser

    2017-05-01

    Current study is concentrated on the extraordinary properties of defective carbon nanotubes (CNTs). The role of vacancy defects in thermal buckling response of precompressed CNTs is explored via molecular dynamics (MD) simulations. Defective CNTs are initially compressed at a certain ratio of their critical buckling strain and then undergo a uniform temperature rise. Comprehensive study is implemented on both armchair and zigzag CNTs with different vacancy defects including monovacancy, symmetric bivacancy and asymmetric bivacancy. The results reveal that defects have a pronounced impact on the buckling behavior of CNTs; interestingly, defective CNTs under compressive pre-load show higher resistance to thermal buckling than pristine ones. In the following, the buckling response of defective CNTs is shown to be dependent on the vacancy defects, location of defects and chirality.

  9. Folic acid fortification prevents neural tube defects and may also reduce cancer risks.

    PubMed

    Jägerstad, Margaretha

    2012-10-01

    The prevalence of neural tube defect (NTD)-affected pregnancies ranges between 0.4 and 2/1000 pregnancies in EU. NTDs result in severe malformations and sometimes miscarriages. Children born with NTD suffer for the rest of their life of disability and chronic healthcare issues, and many women therefore choose termination of pregnancy if NTD is diagnosed prenatally. Women planning for pregnancy are recommended to eat 400 μg folic acid/d, whereas average figures across Europe indicate intakes of ∼250 μg/d for women of fertile age, a gap that could be bridged by implementation of folic acid fortification. The results of mandatory folic acid fortifications introduced in USA and Canada are a decrease between 25 and 45% of NTD pregnancies.   Evidence-based NTD prophylaxis is now practised in more than 60 countries worldwide. EU countries worry over possible cancer risks, but ignore a wealth of studies reporting decreasing cancer risks with folate intakes at recommended levels. Currently, there are indications of a U-shaped relationship, that is, higher cancer risks at low folate intakes (<150 μg/day) and highly elevated folate intakes (>1 mg/day), respectively. However neither the global World Cancer Research review nor EU's European Food Safety Authority report present data on increased cancer risk at physiological folate intake levels. Therefore, EU should act to implement folic acid fortification as NTD prophylaxis as soon as possible. © 2012 The Author/Acta Paediatrica © 2012 Foundation Acta Paediatrica.

  10. Dissociation and diffusion of hydrogen on defect-free and vacancy defective Mg (0001) surfaces: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Han, Zongying; Chen, Haipeng; Zhou, Shixue

    2017-02-01

    First-principles calculations with the density functional theory (DFT) have been carried out to study dissociation and diffusion of hydrogen on defect-free and vacancy defective Mg (0001) surfaces. Results show that energy barriers of 1.42 eV and 1.28 eV require to be overcome for H2 dissociation on defect-free and vacancy defective Mg (0001) surfaces respectively, indicating that reactivity of Mg (0001) surface is moderately increased due to vacancy defect. Besides, the existence of vacancy defect changes the preferential H atom diffusion entrance to the subsurface and reduces the diffusion energy barrier. An interesting remark is that the minimum energy diffusion path of H atom from magnesium surface into bulk is a spiral channel formed by staggered octahedral and tetrahedral interstitials. The diffusion barriers computed for H atom penetration from the surface into inner-layers are all less than 0.70 eV, which is much smaller than the activation energy for H2 dissociation on the Mg (0001) surface. This suggests that H2 dissociation is more likely than H diffusion to be rate-limiting step for magnesium hydrogenation.

  11. Cathodoluminescence studies of defects in coated boron nitride

    NASA Astrophysics Data System (ADS)

    Guerch, Kévin; Dekany, Justin; Dennison, J. R.; Christensen, Justin; Paulmier, Thierry; Guillemet-Fritsch, Sophie; Lenormand, Pascal

    2017-07-01

    Optical emission properties of boron nitride (BN) substrates, BN with alumina (Al2O3) coating, and thermally-annealed alumina-coated boron nitride (an-BN/Al2O3) were investigated under electron irradiation using cathodoluminescence (CL) measurements. Tests were performed, temperatures ranging from ~100 K to ~300 K, with monoenergetic beams from 5 keV to 30 keV, and electron flux densities from 1 nA · cm-2 to 500 nA · cm-2. These experiments were conducted to identify the effects of coating and thermal annealing on the nature and occupation of defect states in different samples with BN substrates. Previous studies have shown that these treatments can limit the charging of BN substrates. Consequently, thorough investigations of electron trapping and recombination processes as a function of low temperature, dose and charging/discharge were performed in order to explain the differences of electrical behaviour and compare the CL spectra of the three different samples studied. Broad features associated with the BN and sharper features resulting from the annealed alumina coating were observed. Changes in the intensity, energy, and width of the features with sample treatments were observed. Different incident beam parameters were used to associate these features with specific types of defect states. The effects of charging, temperature- and dose-dependent conductivity, and thermal annealing and aging of the samples on the CL spectra were investigated. These were used to study defect creation and occupation and to understand the predominant physical mechanisms and main structural and chemical differences between these ceramic configurations.

  12. Defect studies in 4H- Silicon Carbide PVT grown bulk crystals, CVD grown epilayers and devices

    NASA Astrophysics Data System (ADS)

    Byrappa, Shayan M.

    postulated fault vectors by macrostep overgrowth of surface outcrops, has revealed faults to be of four types of which one of the following are discussed in detail which is the Shockley faults. The fault vector were determined by taking into account the contrast from stacking faults in SWBXT undergoing phase shift as the X-ray wave fields cross the fault plane. The deflected dislocations onto the basal plane were responsible for the stacking faults and were observed to be detrimental to the devices grown on them as they replicate to the epilayer. In the wafers studied at different stages of the SiC crystal boule resulted in reduction of threading defects as they at certain stage get deflected out of the crystal causing drop of defects density. [2] A novel technique known as the Ray Tracing Simulation was used to determine the sense of c/c+a dislocations obtained via Grazing-Incidence X-ray Topography. Determination of the complete sense and burgers vector of these dislocations was very important to augment our proposed models on stacking faults associated with these defects. Orientation contrast mechanism in X- ray diffraction topography was previously determined to be the dominant factor in SiC by our group and the same principles were used for the simulation. The results were surmised after extensive comparison between experimental and simulation images for the c+2a defects. [3] With the BPD density down to a record level of few hundred per square centimeter in several wafers in multiple regions made it possible to observe the conversion of sessile Threading Edge Dislocations [TED] to glissile BPDs with this repeating multiple times. Previously the high density of Basal Plane Dislocations [BPD] prevented from discerning the details accurately in the SiC images taken by SWBXT. The contribution of SWBXT in accurately categorizing the nature of dislocations in SiC has enabled the crystal growth community to incorporate strategies to mitigate their influence. One of them has

  13. Positron-annihilation study of radiation defects in sodium azide

    SciTech Connect

    Etin, G.I.; Ryabykh, S.M.

    1987-07-01

    Annihilation-photon angular correlation has been used to examine radiation defects in sodium azide capable of trapping positrons. The calculated and measured characteristics have been determined for various defects, including micropores filled by radiolytic nitrogen. The positron annihilation rates have been determined for the regions around radiation defects.

  14. Knowledge and periconceptional use of folic acid for the prevention of neural tube defects in ethnic communities in the United Kingdom: Systematic review and meta-analysis

    PubMed Central

    Peake, Jordana N; Copp, Andrew J; Shawe, Jill

    2013-01-01

    BACKGROUND: It is widely accepted that periconceptional supplementation with folic acid can prevent a significant proportion of neural tube defects (NTDs). The present study evaluated how folic acid knowledge and periconceptional use for NTD prevention varies by ethnicity in the United Kingdom (U.K.). METHODS: A literature search was conducted to identify studies that included assessment of folic acid knowledge or use in U.K. women of different ethnicities. Only research and referenced sources published after 1991, the year of the landmark Medical Research Council’s Vitamin Study, were included. A meta-analysis was performed of studies that assessed preconceptional folic acid use in Caucasians and non-Caucasians. RESULTS: Five studies met the inclusion criteria for assessment of knowledge and/or use of folic acid supplements in U.K. women including non-Caucasians. The available evidence indicates that South Asians specifically have less knowledge and lower periconceptional use of folic acid than Caucasians; one study found that West Indian and African women also had lower folic acid uptake. A synthesis of results from three of the studies, in a meta-analysis, shows that Caucasians are almost three times more likely to take folic acid before conception than non-Caucasians. CONCLUSION: From the limited evidence available, U.K. women of non-Caucasian ethnicity appear to have less knowledge and a lower uptake of folic acid supplementation than Caucasians during the periconceptional period. Implementing targeted, innovative education campaigns together with a mandatory fortification policy, including the fortification of ethnic minority foods, will be required for maximum prevention of folic acid–preventable NTDs across different ethnic groups. Birth Defects Research (Part A) 97:444–451, 2013. © 2013 Wiley Periodicals, Inc. PMID:23873812

  15. Defective implant osseointegration under protein undernutrition: prevention by PTH or pamidronate.

    PubMed

    Dayer, Romain; Badoud, Isabelle; Rizzoli, René; Ammann, Patrick

    2007-10-01

    Protein deficiency is associated with impaired titanium osseointegration. We studied whether systemic treatment with PTH or pamidronate could influence the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. PTH or pamidronate prevented the deleterious effects of protein undernutrition on bone microarchitecture close to the implant and on mechanical fixation. PTH even significantly improved implant osseointegration. Protein deficiency is highly prevalent among elderly patients hospitalized in orthopedic wards. Reduced protein intake impairs titanium osseointegration in rats. Whether stimulator of bone formation or inhibitor of bone resorption could improve implant osseointegration under protein deprivation is not known. We studied the effects of systemic treatment with PTH or pamidronate on the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. We measured the resistance to pull-out 1-mm-diameter titanium rods implanted into the proximal tibias of 49 adult female rats receiving a normal or an isocaloric low protein diet. After 2 wk on either diet, the implants were inserted, and the rats received PTH(1-34), pamidronate or saline vehicle for 8 wk. The tibias were removed for microCT morphometry, followed by the evaluation of pull-out strength. Pull-out strength was lower in rats fed an isocaloric low protein diet compared with rats fed a normal protein intake (-29%). PTH and pamidronate significantly increased pull-out strength in animals fed a normal or a low protein diet, the effect of PTH being of higher magnitude. The PTH- or pamidronate-mediated increase in pull-out strength was associated with significant increases of relative bone volume, bone-to-implant contact, and trabecular thickness, whereas trabecular spacing was reduced, in the vicinity of the implants. We confirmed that isocaloric low protein intake impairs

  16. Congenital heart defects in newborns with apparently isolated single gastrointestinal malformation: A retrospective study.

    PubMed

    Schierz, Ingrid Anne Mandy; Pinello, Giuseppa; Giuffrè, Mario; La Placa, Simona; Piro, Ettore; Corsello, Giovanni

    2016-12-01

    Congenital gastrointestinal system malformations/abdominal wall defects (GISM) may appear as isolated defects (single or complex), or in association with multiple malformations. The high incidence of association of GISM and congenital heart defects (CHD) in patients with syndromes and malformative sequences is known, but less expected is the association of apparently isolated single GISM and CHD. The aim of this study was to investigate the frequency of CHD in newborns with isolated GISM, and the possibility to modify the diagnostic-therapeutic approach just before the onset of cardiac symptoms or complications. Anamnestic, clinical, and imaging data of newborns requiring abdominal surgery for GISM, between 2009 and 2014, were compared with a control group of healthy newborns. Distribution of GISM and cardiovascular abnormalities were analyzed, and risk factors for adverse outcomes were identified. Seventy-one newborns with isolated GISM were included in this study. More frequent GISM were intestinal rotation and fixation disorders. CHD were observed in 15.5% of patients, augmenting their risk for morbidity. Risk factors for morbidity related to sepsis were identified in central venous catheter, intestinal stoma, and H2-inhibitor-drugs. Moreover, 28.2% of newborns presented only functional cardiac disorders but an unexpectedly higher mortality. The high incidence of congenital heart disease in infants with apparently isolated GISM confirms the need to perform an echocardiographic study before surgery to improve perioperative management and prevent complications such as sepsis and endocarditis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. The "Telefono Rosso": a service for the prevention of birth defects and for the evaluation of teratogenic risk.

    PubMed

    Mastroiacovo, P; Serafini, M; Pagano, M; De Santis, M; Vercillo, I; Celestini, E

    1993-01-01

    The "Telefono Rosso" ("Red telephone") is a specialized service for preconceptional counselling and teratogenic risk evaluation. In both cases the choice of telephone communication allows to reach a wide basin of users with personalized information. The service finds one of its main reasons in the marked disinformation which exists in this field and in the wrong risk perception shown by a high proportion of users. In addition to serving the community to prevent birth defects and to prevent some induced abortions, the "Telefono Rosso" represents a unique opportunity to add to the current body of knowledge by documenting the outcomes of pregnancies exposed to a variety of agents. In this respect the "Telefono Rosso" may be considered an additional source of post-marketing surveillance.

  18. Birth Defects (For Parents)

    MedlinePlus

    ... there is a problem with a baby's body chemistry, it is called a metabolic birth defect. Metabolic defects prevent the body from properly breaking down food to create energy. Examples of metabolic defects include ...

  19. Defect-based graphene nanoribbon photodetectors: A numerical study

    SciTech Connect

    Zarei, M. H.; Sharifi, M. J.

    2016-06-07

    Recently, some photodetectors based on graphene have been proposed. In all of these works, current generation was carried out by separation of photo-excited carriers using an electric field, either internal or external. In this work, a new method of producing current which is based on different transmission coefficients for electrons and holes when they travel toward any of the two contacts is proposed. To this end, a single Stone–Wales defect close to one of the two contacts was used to break the channel symmetry. In order to confirm the idea, the non-equilibrium Green's function formalism in real space in conjunction with the tight binding method was used in simulations. In addition, to clarify the results, we present a classical model in which different diffusion constants are assumed for the left going and the right going carriers. Additional simulations for different positions of the defect, different lengths of the ribbon, and different bias voltages were performed, and the results are included in this study.

  20. Triple-negative breast cancer risk in women is defined by the defect of estrogen signaling: preventive and therapeutic implications

    PubMed Central

    Suba, Zsuzsanna

    2014-01-01

    Epidemiologic studies strongly support that triple-negative breast cancers (TNBCs) may be distinct entities as compared with estrogen receptor (ER)+ tumors, suggesting that the etiologic factors, clinical characteristics, and therapeutic possibilities may vary by molecular subtypes. Many investigations propose that reproductive factors and exogenous hormone use differently or even quite inversely affect the risk of TNBCs and ER+ cancers. Controversies concerning the exact role of even the same risk factor in TNBC development justify that the biological mechanisms behind the initiation of both TNBCs and non-TNBCs are completely obscure. To arrive at a comprehensive understanding of the etiology of different breast cancer subtypes, we should also reconsider our traditional concepts and beliefs regarding cancer risk factors. Malignancies are multicausal, but the disturbance of proper estrogen signaling seems to be a crucial risk factor for the development of mammary cancers. The grade of defect in metabolic and hormonal equilibrium is directly associated with TNBC risk for women during their whole life. Inverse impact of menopausal status or parity on the development of ER+ and ER− breast cancers may not be possible; these controversial results derive from the misinterpretation of percentage-based statistical evaluations. Exogenous or parity-associated excessive estrogen supply is suppressive against breast cancer, though the lower the ER expression of tumors, the weaker the anticancer capacity. In women, the most important preventive strategy against breast cancers – included TNBCs – is the strict control and maintenance of hormonal equilibrium from early adolescence through the whole lifetime, particularly during the periods of great hormonal changes. PMID:24482576

  1. Computer programs for eddy-current defect studies

    SciTech Connect

    Pate, J. R.; Dodd, C. V.

    1990-06-01

    Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs.

  2. The study of develop optimization to control various resist defect in Photomask fabrication

    NASA Astrophysics Data System (ADS)

    Lim, JongHoon; Kim, ByungJu; Son, JaeSik; Park, EuiSang; Kim, SangPyo; Yim, DongGyu

    2015-07-01

    To reduce the pattern size in photomask is an inevitable trend because of the minimization of chip size. So it makes a big challenge to control defects in photomask industry. Defects below a certain size that had not been any problem in previous technology node are becoming an issue as the patterns are smaller. Therefore, the acceptable tolerance levels for current defect size and quantity are dramatically reduced. Because these defects on photomask can be the sources of the repeating defects on wafer, small size defects smaller than 200nm should not be ignored any more. Generally, almost defects are generated during develop process and etch process. Especially it is difficult to find the root cause of defects formed during the develop process because of their various types and very small size. In this paper, we studied how these small defects can be eliminated by analyzing the defects and tuning the develop process. There are 3 types of resist defects which are named as follows. The first type is `Popcorn' defect which is mainly occurred in negative resist and exists on the dark features. The second type is `Frog eggs' defect which is occurred in 2nd process of HTPSM and exists on the wide space area. The last type is `Spot' defect which also exists on the wide space area. These defects are generally appeared on the entire area of a plate and the number of these defects is about several hundred. It is thought that the original source is the surface's hydrophilic state before develop process or the incongruity between resist and developer. This study shows that the optimizing the develop process can be a good solution for some resist defects.

  3. Surgical pathology report defects: a College of American Pathologists Q-Probes study of 73 institutions.

    PubMed

    Volmar, Keith E; Idowu, Michael O; Hunt, Jennifer L; Souers, Rhona J; Meier, Frederick A; Nakhleh, Raouf E

    2014-05-01

    The rate of surgical pathology report defects is an indicator of quality and it affects clinician satisfaction. To establish benchmarks for defect rates and defect fractions through a large, multi-institutional prospective application of standard taxonomy. Participants in a 2011 Q-Probes study of the College of American Pathologists prospectively reviewed all surgical pathology reports that underwent changes to correct defects and reported details regarding the defects. Seventy-three institutions reported 1688 report defects discovered in 360,218 accessioned cases, for an aggregate defect rate of 4.7 per 1000 cases. Median institutional defect rate was 5.7 per 1000 (10th to 90th percentile range, 13.5-0.9). Defect rates were higher in institutions with a pathology training program (8.5 versus 5.0 per 1000, P = .01) and when a set percentage of cases were reviewed after sign-out (median, 6.7 versus 3.8 per 1000, P = .10). Defect types were as follows: 14.6% misinterpretations, 13.3% misidentifications, 13.7% specimen defects, and 58.4% other report defects. Overall, defects were most often detected by pathologists (47.4%), followed by clinicians (22.0%). Misinterpretations and specimen defects were most often detected by pathologists (73.5% and 82.7% respectively, P < .001), while misidentifications were most often discovered by clinicians (44.6%, P < .001). Misidentification rates were lower when all malignancies were reviewed by a second pathologist before sign-out (0.0 versus 0.6 per 1000, P < .001), and specimen defect rates were lower when intradepartmental review of difficult cases was conducted after sign-out (0.0 versus 0.4 per 1000, P = .02). This study provides benchmarking data on report defects and defect fractions using standardized taxonomy.

  4. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid

    USDA-ARS?s Scientific Manuscript database

    The objective of this study was to evaluate the beneficial effects of different levels of folic acid administration on the prevalence of neural tube defects, with a concurrent assessment of other potential benefits or adverse effects. The evaluation was based on a systematic review of the published ...

  5. Oxygen defects in GaAs: A hybrid functional study

    NASA Astrophysics Data System (ADS)

    Colleoni, Davide; Pasquarello, Alfredo

    2016-03-01

    Using hybrid density functional calculations, we address the structural properties, formation energies, and charge transition levels of a variety of oxygen defects in GaAs. The set of considered defects comprises the bridging O atom in a As-O-Ga configuration, interstitial O atoms in tetrahedral sites, and O atoms substitutional to either Ga (OGa) or As atoms (OAs). In addition, we consider an As vacancy containing two O atoms, for which the most stable configurations are found through the use of molecular dynamics simulations, and defect complexes involving a OAs defect bound to either one or two AsGa antisites, denoted AsGa-OAs and (AsGa)2-OAs , respectively. We find that the bridging O defect and the AsGa-OAs and (AsGa)2-OAs complexes are the most stable oxygen defects in GaAs. The actual occurrence of these defects is examined against two criteria. The first criterion concerns the stability against O dissociation and is evaluated via the calculation of dissociation energies. The second criterion involves the defect formation at thermodynamic equilibrium and is inferred from the comparison between the formation energy of the oxygen defect and that of its O-related dissociation product (bridging O defect). Both the AsGa-OAs and (AsGa)2-OAs complexes satisfy these criteria and are stable against O dissociation. Further analysis in cooled-down conditions leads us to dismiss the AsGa-OAs defect due to the more favorable bonding of two rather than one AsGa antisites. The conclusion that only the bridging O defect and the (AsGa)2-OAs complex are expected to occur is in accord with experimental observations.

  6. Defects in the Error Prevention Oxidized Guanine System Potentiate Stationary-Phase Mutagenesis in Bacillus subtilis▿

    PubMed Central

    Vidales, Luz E.; Cárdenas, Lluvia C.; Robleto, Eduardo; Yasbin, Ronald E.; Pedraza-Reyes, Mario

    2009-01-01

    Previous studies showed that a Bacillus subtilis strain deficient in mismatch repair (MMR; encoded by the mutSL operon) promoted the production of stationary-phase-induced mutations. However, overexpression of the mutSL operon did not completely suppress this process, suggesting that additional DNA repair mechanisms are involved in the generation of stationary-phase-associated mutants in this bacterium. In agreement with this hypothesis, the results presented in this work revealed that starved B. subtilis cells lacking a functional error prevention GO (8-oxo-G) system (composed of YtkD, MutM, and YfhQ) had a dramatic propensity to increase the number of stationary-phase-induced revertants. These results strongly suggest that the occurrence of mutations is exacerbated by reactive oxygen species in nondividing cells of B. subtilis having an inactive GO system. Interestingly, overexpression of the MMR system significantly diminished the accumulation of mutations in cells deficient in the GO repair system during stationary phase. These results suggest that the MMR system plays a general role in correcting base mispairing induced by oxidative stress during stationary phase. Thus, the absence or depression of both the MMR and GO systems contributes to the production of stationary-phase mutants in B. subtilis. In conclusion, our results support the idea that oxidative stress is a mechanism that generates genetic diversity in starved cells of B. subtilis, promoting stationary-phase-induced mutagenesis in this soil microorganism. PMID:19011023

  7. Analytic study to evaluate associations between hazardous waste sites and birth defects. Final report

    SciTech Connect

    Marshall, E.G.; Gensburg, L.J.; Geary, N.S.; Deres, D.A.; Cayo, M.R.

    1995-06-01

    A study was conducted to evaluate the risk of two types of birth defects (central nervous system and musculoskeletal defects) associated with mothers` exposure to solvents, metals, and pesticides through residence near hazardous waste sites. The only environmental factor showing a statistically significant elevation in risk was living within one mile of industrial or commercial facilities emitting solvents into the air. Residence near these facilities showed elevated risk for central nervous system defects but no elevated risks for musculoskeletal defects.

  8. Folic acid in the prevention of neural tube defect--a programme for Malaysia?

    PubMed

    Ho, J J

    2004-03-01

    There is good evidence that folic acid is safe and efficacious for reducing neural tube defect (NTD). All women capable of becoming pregnant should take 400 microgram daily. This can be given in the form of a daily vitamin supplement, by food fortification, or by increasing natural dietary folates. Compulsory grain fortification has been shown to reduce NTD in a population but supplementation and dietary advice have not. Malaysia should work towards a programme of grain fortification and use alternative strategies to reach sections of the population that would not be covered but several research questions need to be answered before a programme could be implemented in Malaysia.

  9. Sirt3 prevents maternal obesity-associated oxidative stress and meiotic defects in mouse oocytes.

    PubMed

    Zhang, Liang; Han, Longsen; Ma, Rujun; Hou, Xiaojing; Yu, Yang; Sun, Shaochen; Xu, Yinxue; Schedl, Tim; Moley, Kelle H; Wang, Qiang

    2015-01-01

    Maternal obese environment has been reported to induce oxidative stress and meiotic defects in oocytes, however the underlying molecular mechanism remains unclear. Here, using mice fed a high fat diet (HFD) as an obesity model, we first detected enhanced reactive oxygen species (ROS) content and reduced Sirt3 expression in HFD oocytes. We further observed that specific depletion of Sirt3 in control oocytes elevates ROS levels while Sirt3 overexpression attenuates ROS production in HFD oocytes, with significant suppression of spindle disorganization and chromosome misalignment phenotypes that have been reported in the obesity model. Candidate screening revealed that the acetylation status of lysine 68 on superoxide dismutase (SOD2K68) is dependent on Sirt3 deacetylase activity in oocytes, and acetylation-mimetic mutant SOD2K68Q results in almost threefold increase in intracellular ROS. Moreover, we found that acetylation levels of SOD2K68 are increased by ~80% in HFD oocytes and importantly, that the non-acetylatable-mimetic mutant SOD2K68R is capable of partially rescuing their deficient phenotypes. Together, our data identify Sirt3 as an important player in modulating ROS homeostasis during oocyte development, and indicate that Sirt3-dependent deacetylation of SOD2 plays a protective role against oxidative stress and meiotic defects in oocytes under maternal obese conditions.

  10. Sirt3 prevents maternal obesity-associated oxidative stress and meiotic defects in mouse oocytes

    PubMed Central

    Zhang, Liang; Han, Longsen; Ma, Rujun; Hou, Xiaojing; Yu, Yang; Sun, Shaochen; Xu, Yinxue; Schedl, Tim; Moley, Kelle H; Wang, Qiang

    2015-01-01

    Maternal obese environment has been reported to induce oxidative stress and meiotic defects in oocytes, however the underlying molecular mechanism remains unclear. Here, using mice fed a high fat diet (HFD) as an obesity model, we first detected enhanced reactive oxygen species (ROS) content and reduced Sirt3 expression in HFD oocytes. We further observed that specific depletion of Sirt3 in control oocytes elevates ROS levels while Sirt3 overexpression attenuates ROS production in HFD oocytes, with significant suppression of spindle disorganization and chromosome misalignment phenotypes that have been reported in the obesity model. Candidate screening revealed that the acetylation status of lysine 68 on superoxide dismutase (SOD2K68) is dependent on Sirt3 deacetylase activity in oocytes, and acetylation-mimetic mutant SOD2K68Q results in almost threefold increase in intracellular ROS. Moreover, we found that acetylation levels of SOD2K68 are increased by ∼80% in HFD oocytes and importantly, that the non-acetylatable-mimetic mutant SOD2K68R is capable of partially rescuing their deficient phenotypes. Together, our data identify Sirt3 as an important player in modulating ROS homeostasis during oocyte development, and indicate that Sirt3-dependent deacetylation of SOD2 plays a protective role against oxidative stress and meiotic defects in oocytes under maternal obese conditions. PMID:25790176

  11. DLTS and EPR study of defects in H implanted silicon

    NASA Astrophysics Data System (ADS)

    Mikšić, V.; Pivac, B.; Rakvin, B.; Zorc, H.; Corni, F.; Tonini, R.; Ottaviani, G.

    2002-01-01

    Single crystal CZ Si samples were implanted with hydrogen ions to the dose of 2E16 He ions/cm 2 at room temperature and subsequently annealed in vacuum in the temperature interval from 100 to 900 °C. The aim of the experiment was to determine the conditions for bubble formation within the solid film, which may have important technological application. Defects produced in such samples were studied by deep-level transient spectroscopy (DLTS) and electron paramagnetic resonance (EPR) spectroscopy. It is shown that high dose hydrogen implantation produces vacancy-related and silicon selfinterstitial clusters. The latter are thought to be responsible for the formation of the weak displacement field. The annealing at higher temperatures creates multivacancy-related clusters responsible for the strong displacement field formation.

  12. Estimate of the potential impact of folic acid fortification of corn masa flour on the prevention of neural tube defects.

    PubMed

    Tinker, Sarah C; Devine, Owen; Mai, Cara; Hamner, Heather C; Reefhuis, Jennita; Gilboa, Suzanne M; Dowling, Nicole F; Honein, Margaret A

    2013-10-01

    Hispanics in the US have a higher prevalence of neural tube defect (NTD) -affected pregnancies than non-Hispanic whites, and lower median total folic acid (FA) intake. FA fortification of corn masa flour (CMF) is a policy-level intervention for NTD prevention; however, the impact on NTD prevalence has not been estimated. We developed a model to estimate the percentage reduction in prevalence of spina bifida and anencephaly (NTDs) that could occur with FA fortification of CMF. Model inputs included estimates of the percentage reduction in United States NTD prevalence attributed to FA fortification of enriched cereal grain products (1995-1996 vs. 1998-2002), the increase in median FA intake after enriched cereal grain product fortification, and the estimated increase in median FA intake that could occur with CMF fortification at the same level as enriched cereal grain products (140 μg/100 g). We used Monte Carlo simulation to quantify uncertainty. We stratified analyses by racial/ethnic group and rounded results to the nearest 10. We estimated CMF fortification could prevent 30 Hispanic infants from having spina bifida (95% uncertainty interval: 0, 80) and 10 infants from having anencephaly (95% uncertainty interval: 0, 40) annually. The estimated impact among non-Hispanic whites and blacks was smaller. CMF fortification with FA could prevent from 0 to 120 infants, with the most likely value of approximately 40, from having spina bifida or anencephaly among Hispanics, the population most likely to benefit from the proposed intervention. While this estimated reduction is unlikely to be discernible using current birth defect surveillance methods, it still suggests an important benefit to the target population. Copyright © 2013 Wiley Periodicals, Inc.

  13. Use of an Osteoplastic Flap for the Prevention of Mastoidectomy Retroauricular Defects

    PubMed Central

    Bento, Ricardo Ferreira; Tsuji, Robinson Koji; Fonseca, Anna Carolina de Oliveira; Alves, Ricardo Dourado

    2016-01-01

    Introduction After mastoidectomy, patients usually complain of bone depressions in the retroauricular region in the surgical site, especially in procedures that require extensive cortical resections. This causes inconveniences such as difficulty wearing glasses, cleaning, and aesthetics complaints. Objective This study aims to describe a vascularized flap surgical technique that uses the mastoid cortical bone adhered to the periosteum, which is pedicled on the anterior portion and repositioned at the end of the surgery. This ensures the coverage of the mastoid cavity generated by surgery and prevents ear retraction into the cavity. This preliminary report describes the technique and intraoperative and immediate postoperative complications. Methods After retroauricular incision, periosteal exposure is performed. A U-shaped incision is required for the procedure and delimits a periosteum area appropriate to the size of the mastoidectomy. The cortical bone is opened using a 2.5 mm drill around the perimeter of the “U,” at a 3 mm depth. A chisel is introduced through the surface cells of the mastoid, and a hammer evolves into the anterior direction. The flap is lifted, leaving the periosteum adhered to it and forming a cap. The flap is anteriorly fixed to not hinder the surgery, and repositioned at the end. The periosteum is then sutured to the adjacent periosteum. Results The first 14 cases had no intraoperative complications and were firm and stable when digital pressure was applied during the intraoperative and immediate postoperative periods. Conclusion The osteoplastic flap pedicle is a safe and simple procedure, with good results in the immediate postoperative period. PMID:28382122

  14. Use of an Osteoplastic Flap for the Prevention of Mastoidectomy Retroauricular Defects.

    PubMed

    Bento, Ricardo Ferreira; Tsuji, Robinson Koji; Fonseca, Anna Carolina de Oliveira; Alves, Ricardo Dourado

    2017-04-01

    Introduction After mastoidectomy, patients usually complain of bone depressions in the retroauricular region in the surgical site, especially in procedures that require extensive cortical resections. This causes inconveniences such as difficulty wearing glasses, cleaning, and aesthetics complaints. Objective This study aims to describe a vascularized flap surgical technique that uses the mastoid cortical bone adhered to the periosteum, which is pedicled on the anterior portion and repositioned at the end of the surgery. This ensures the coverage of the mastoid cavity generated by surgery and prevents ear retraction into the cavity. This preliminary report describes the technique and intraoperative and immediate postoperative complications. Methods After retroauricular incision, periosteal exposure is performed. A U-shaped incision is required for the procedure and delimits a periosteum area appropriate to the size of the mastoidectomy. The cortical bone is opened using a 2.5 mm drill around the perimeter of the "U," at a 3 mm depth. A chisel is introduced through the surface cells of the mastoid, and a hammer evolves into the anterior direction. The flap is lifted, leaving the periosteum adhered to it and forming a cap. The flap is anteriorly fixed to not hinder the surgery, and repositioned at the end. The periosteum is then sutured to the adjacent periosteum. Results The first 14 cases had no intraoperative complications and were firm and stable when digital pressure was applied during the intraoperative and immediate postoperative periods. Conclusion The osteoplastic flap pedicle is a safe and simple procedure, with good results in the immediate postoperative period.

  15. Transient inhibition of the ERK pathway prevents cerebellar developmental defects and improves long-term motor functions in murine models of neurofibromatosis type 1.

    PubMed

    Kim, Edward; Wang, Yuan; Kim, Sun-Jung; Bornhorst, Miriam; Jecrois, Emmanuelle S; Anthony, Todd E; Wang, Chenran; Li, Yi E; Guan, Jun-Lin; Murphy, Geoffrey G; Zhu, Yuan

    2014-12-23

    Individuals with neurofibromatosis type 1 (NF1) frequently exhibit cognitive and motor impairments and characteristics of autism. The cerebellum plays a critical role in motor control, cognition, and social interaction, suggesting that cerebellar defects likely contribute to NF1-associated neurodevelopmental disorders. Here we show that Nf1 inactivation during early, but not late stages of cerebellar development, disrupts neuronal lamination, which is partially caused by overproduction of glia and subsequent disruption of the Bergmann glia (BG) scaffold. Specific Nf1 inactivation in glutamatergic neuronal precursors causes premature differentiation of granule cell (GC) precursors and ectopic production of unipolar brush cells (UBCs), indirectly disrupting neuronal migration. Transient MEK inhibition during a neonatal window prevents cerebellar developmental defects and improves long-term motor performance of Nf1-deficient mice. This study reveals essential roles of Nf1 in GC/UBC migration by generating correct numbers of glia and controlling GC/UBC fate-specification/differentiation, identifying a therapeutic prevention strategy for multiple NF1-associcated developmental abnormalities.

  16. Transient inhibition of the ERK pathway prevents cerebellar developmental defects and improves long-term motor functions in murine models of neurofibromatosis type 1

    PubMed Central

    Kim, Edward; Wang, Yuan; Kim, Sun-Jung; Bornhorst, Miriam; Jecrois, Emmanuelle S; Anthony, Todd E; Wang, Chenran; Li, Yi E; Guan, Jun-Lin; Murphy, Geoffrey G; Zhu, Yuan

    2014-01-01

    Individuals with neurofibromatosis type 1 (NF1) frequently exhibit cognitive and motor impairments and characteristics of autism. The cerebellum plays a critical role in motor control, cognition, and social interaction, suggesting that cerebellar defects likely contribute to NF1-associated neurodevelopmental disorders. Here we show that Nf1 inactivation during early, but not late stages of cerebellar development, disrupts neuronal lamination, which is partially caused by overproduction of glia and subsequent disruption of the Bergmann glia (BG) scaffold. Specific Nf1 inactivation in glutamatergic neuronal precursors causes premature differentiation of granule cell (GC) precursors and ectopic production of unipolar brush cells (UBCs), indirectly disrupting neuronal migration. Transient MEK inhibition during a neonatal window prevents cerebellar developmental defects and improves long-term motor performance of Nf1-deficient mice. This study reveals essential roles of Nf1 in GC/UBC migration by generating correct numbers of glia and controlling GC/UBC fate-specification/differentiation, identifying a therapeutic prevention strategy for multiple NF1-associcated developmental abnormalities. DOI: http://dx.doi.org/10.7554/eLife.05151.001 PMID:25535838

  17. Descriptive study on neural tube defects in Argentina.

    PubMed

    Sargiotto, Carla; Bidondo, María Paz; Liascovich, Rosa; Barbero, Pablo; Groisman, Boris

    2015-06-01

    Neural tube defects (NTDs) are the most common congenital anomalies of the central nervous system. Prevalence of NTDs varies depending on geographic region and folic acid fortification. The main objectives of this study are to analyze the prevalences of NTDs reported to the National Registry of Congenital Anomalies of Argentina (RENAC) during the period 2009 to 2013, to compare them with data from other selected surveillance systems of the Americas, and to evaluate the impact of folic acid fortification on the prevalence of NTDs in Argentina. We analyzed changes in prevalence between 2009 and 2013 for the RENAC, and differences in prevalence between RENAC and other surveillance systems. We evaluated changes for the pre and postfortification time periods in Argentina. In Argentina, anencephaly and spina bifida showed no statistically significant variation between 2009 and 2013, and encephalocele showed a statistically significant decline. The RENAC showed a statistically significant higher prevalence for all three defects when compared with surveillance systems from Chile, Colombia, and Costa Rica, and a statistically significant lower birth prevalence than Cuba for anencephaly. No differences were observed when comparing it to the Atlanta-USA and Mexico systems. A significant decrease in prevalence was observed for all three anomalies for the postfortification period in Argentina. The characteristics of cases reported to the RENAC are similar to those already reported in the literature. The differences in prevalence between the RENAC and other surveillance systems could be artifactual or real. We confirmed the decrease of prevalence of NTDs after folic acid fortification. © 2015 Wiley Periodicals, Inc.

  18. Hybrid functional studies of defects and hole polarons in oxides

    NASA Astrophysics Data System (ADS)

    Varley, Joel

    Transparent conducting oxides (TCOs) are ubiquitous, appearing in windows, flat-panel displays, solar cells, solid-state lighting, and transistors that all exploit TCOs' combination of high electrical conductivity and optical transparency. Thanks to this large and growing list of applications, there has been a surge of interest in the science of these materials, focusing on the fundamental properties and doping opportunities in traditional TCOs as well as the exploration of promising new candidate materials. Hybrid density functional theory has proven instrumental in elucidating the physics of TCOs. One example is the study of dopants and defects that determine the conductivity. Accurate formation energies and charge-state transition levels can now be obtained thanks to the accurate electronic structure provided by a hybrid functional. This allows us to address the origins of unintentional conductivity: for SnO2, In2O3, and Ga2O3, we demonstrate that this is not due to native defects such as oxygen vacancies, but must be attributed to unintentional incorporation of impurities. We can also provide guidelines for achieving higher doping levels, suggesting several impurities as candidate donors with high solubility. Limitations on doping due to the formation or incorporation of compensating centers are addressed as well. Hybrid functional calculations also overcome the shortcomings associated with traditional local or semi-local functionals, which do not properly describe charge localization. Hybrid functionals accurately describe polaron formation, i.e., the self-trapping of holes when p - type doping of the oxide materials is attempted. Consequences of polaron formation for optical characterization of the material will be discussed. This work was performed in collaboration with Anderson Janotti and Chris G. Van de Walle, and was in part under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  19. Multiple defects, including premature apoptosis, prevent Kaposi's sarcoma-associated herpesvirus replication in murine cells.

    PubMed

    Austgen, Kathryn; Oakes, Scott A; Ganem, Don

    2012-02-01

    The development of a mouse model for Kaposi's sarcoma-associated herpesvirus (KSHV) infection has been impeded by the limited host range of the virus. Here, we have examined the molecular basis of this host range restriction. KSHV efficiently enters murine cells and establishes latency. However, ectopic expression of the lytic switch protein RTA (replication and transcription activator) in these cells induces little viral gene expression and no virus production. Upon treatment with histone deacetylase inhibitors, KSHV-infected murine cells display more extensive but aberrant viral transcription and do not support either viral DNA synthesis or the production of infectious virions. These aberrantly infected cells also display markedly enhanced apoptosis. Genetic ablation of the mitochondrial apoptotic pathway in these cells prolongs their survival and permits viral DNA replication but does not rescue the generation of virions. We conclude that multiple defects, both prior to and following DNA synthesis, restrict lytic KSHV infection in murine cells.

  20. Enhancing native defect sensitivity for EUV actinic blank inspection: optimized pupil engineering and photon noise study

    NASA Astrophysics Data System (ADS)

    Wang, Yow-Gwo; Neureuther, Andrew; Naulleau, Patrick

    2016-03-01

    In this paper, we discuss the impact of optimized pupil engineering and photon noise on native defect sensitivity in EUV actinic blank inspection. Native defects include phase-dominated defects, absorber defects, and defects with a combination of phase and absorption behavior. First, we extend the idea of the Zernike phase contrast (ZPC) method and study the impact of optimum phase shift in the pupil plane on native defect sensitivity, showing a 23% signal-to-noise ratio (SNR) enhancement compare to bright field (BF) for a phase defect with 20% absorption. We also describe the possibility to increase target defect SNR on target defect sizes at the price of losing the sensitivity on smaller (non-critical) defects. Moreover, we show the advantage of the optimized phase contrast (OZPC) method over BF EUV actinic blank inspection. A single focus scan from OZPC has better inspection efficiency over BF. Second, we make a detailed comparison between the phase contrast with apodization (AZPC) method and dark field (DF) method based on defect sensitivity in the presence of both photon shot noise and camera noise. Performance is compared for a variety of photon levels, mask roughness conditions, and combinations of defect phase and absorption.

  1. Using defects to store energy in materials - a computational study.

    PubMed

    Lu, I-Te; Bernardi, Marco

    2017-06-13

    Energy storage occurs in a variety of physical and chemical processes. In particular, defects in materials can be regarded as energy storage units since they are long-lived and require energy to be formed. Here, we investigate energy storage in non-equilibrium populations of materials defects, such as those generated by bombardment or irradiation. We first estimate upper limits and trends for energy storage using defects. First-principles calculations are then employed to compute the stored energy in the most promising elemental materials, including tungsten, silicon, graphite, diamond and graphene, for point defects such as vacancies, interstitials and Frenkel pairs. We find that defect concentrations achievable experimentally (~0.1-1 at.%) can store large energies per volume and weight, up to ~5 MJ/L and 1.5 MJ/kg for covalent materials. Engineering challenges and proof-of-concept devices for storing and releasing energy with defects are discussed. Our work demonstrates the potential of storing energy using defects in materials.

  2. Immersion defectivity study with volume production immersion lithography tool for 45 nm node and below

    NASA Astrophysics Data System (ADS)

    Nakano, Katsushi; Nagaoka, Shiro; Yoshida, Masato; Iriuchijima, Yasuhiro; Fujiwara, Tomoharu; Shiraishi, Kenichi; Owa, Soichi

    2008-03-01

    Volume production of 45nm node devices utilizing Nikon's S610C immersion lithography tool has started. Important to the success in achieving high-yields in volume production with immersion lithography has been defectivity reduction. In this study we evaluate several methods of defectivity reduction. The tools used in our defectivity analysis included a dedicated immersion cluster tools consisting of a Nikon S610C, a volume production immersion exposure tool with NA of 1.3, and a resist coater-developer LITHIUS i+ from TEL. In our initial procedure we evaluated defectivity behavior by comparing on a topcoat-less resist process to a conventional topcoat process. Because of its simplicity the topcoatless resist shows lower defect levels than the topcoat process. In a second study we evaluated the defect reduction by introducing the TEL bevel rinse and pre-immersion bevel cleaning techniques. This technique was shown to successfully reduce the defect levels by reducing the particles at the wafer bevel region. For the third defect reduction method, two types of tool cleaning processes are shown. Finally, we discuss the overall defectivity behavior at the 45nm node. To facilitate an understanding of the root cause of the defects, defect source analysis (DSA) was applied to separate the defects into three classes according to the source of defects. DSA analysis revealed that more than 99% of defects relate to material and process, and less than 1% of the defects relate to the exposure tool. Material and process optimization by collaborative work between exposure tool vendors, track vendors and material vendors is a key for success of 45nm node device manufacturing.

  3. A study of irradiation-induced defects in silicon using low temperature photoluminescence

    NASA Technical Reports Server (NTRS)

    Streetman, B. G.

    1971-01-01

    Irradiation-induced defects in silicon, using low temperature photoluminescence as a probe of defect properties were investigated. The goal of this research was to gain new understanding of defects which degrade solar cell characteristics in a radiation environment. In this regard, an important aspect of this program was a study of radiation damage and annealing in lithium doped silicon, which is useful in reducing solar cell degradation. Luminescence was used to study defects because this property reveals electron transitions through a number of defect energy levels at any given annealing stage; the luminescence spectra give excellent resolution of many defect energy levels, and these measurements can be used to give defect symmetry in the lattice, impurity dependence, and annealing properties.

  4. Plane-wave pseudopotential study of point defects in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Crocombette, J. P.; Jollet, F.; Nga, L. Thien; Petit, T.

    2001-09-01

    A study on uranium and oxygen point defects in uranium dioxide using the ab initio plane-wave pseudopotential method in the local density approximation of the density functional theoretical framework is presented. Norm conserving pseudopotentials are used to describe oxygen and uranium atoms. The uranium pseudopotential is specifically described. Its validity is ascertained thanks to a detailed structural study of uranium dioxide and of three phases of metallic uranium (fcc, bcc, and α phase). The free energies of formation of both intrinsic (Frenkel pairs and Schottky defect) and extrinsic (single vacancies or interstitials) defects are calculated. The obtained values form a reliable set of numerical data that are analyzed in the framework of the point defect model which is commonly used to assess defect concentrations in uranium dioxide and their variation with stoichiometry. From the obtained results, the ability of the point defect model to accurately reproduce defect concentrations in uranium dioxide is discussed.

  5. Usefulness of a bioengineered oral mucosa model for preventing palate bone alterations in rabbits with a mucoperiostial defect.

    PubMed

    Fernández-Valadés-Gámez, Ricardo; Garzón, Ingrid; Liceras-Liceras, Esther; España-López, Antonio; Carriel, Víctor; Martin-Piedra, Miguel-Ángel; Muñoz-Miguelsanz, María-Ángeles; Sánchez-Quevedo, Maria-Carmen; Alaminos, Miguel; Fernández-Valadés, Ricardo

    2016-02-19

    The use of mucoperiostial flaps during cleft palate surgery is associated with altered palatal bone growth and development. We analyzed the potential usefulness of a bioengineered oral mucosa in an in vivo model of cleft palate. First, a 4 mm palate defect was created in one side of the palate oral mucosa of 3 week-old New Zealand rabbits, and a complete autologous bioengineered oral mucosa (BOM) or acellular fibrin-agarose scaffold (AS) was implanted. No material was implanted in the negative controls (NC), and positive controls were not subjected to palatal defect (PC). Animals were allowed to grow for 6 months and the results were analyzed morphologically (palate mucosa and bone size) and histologically. Results show that palatal mucosa and bone growth and development were significantly altered in NC and AS animals, whereas BOM animals had similar results to PC and the bioengineered oral mucosa was properly integrated in the host palate. The amount and compaction of collagen fibers was similar between BOM and PC, and both groups of animals had comparable contents of proteoglycans and glycoproteins at the palate bone. No differences were found for decorin, osteocalcin and BMP2. The use of bioengineered oral mucosa substitutes is able to improve palate growth and maturation by preventing the alterations found in animals with denuded palate bone. These results support the potential clinical usefulness of BOM substitutes for the treatment of patients with cleft palate and other conditions in which palate mucosa grafts are necessary with consequent bone denudation.

  6. Maternally provided LSD1/KDM1A enables the maternal-to-zygotic transition and prevents defects that manifest postnatally

    PubMed Central

    Wasson, Jadiel A; Simon, Ashley K; Myrick, Dexter A; Wolf, Gernot; Driscoll, Shawn; Pfaff, Samuel L; Macfarlan, Todd S; Katz, David J

    2016-01-01

    Somatic cell nuclear transfer has established that the oocyte contains maternal factors with epigenetic reprogramming capacity. Yet the identity and function of these maternal factors during the gamete to embryo transition remains poorly understood. In C. elegans, LSD1/KDM1A enables this transition by removing H3K4me2 and preventing the transgenerational inheritance of transcription patterns. Here we show that loss of maternal LSD1/KDM1A in mice results in embryonic arrest at the 1-2 cell stage, with arrested embryos failing to undergo the maternal-to-zygotic transition. This suggests that LSD1/KDM1A maternal reprogramming is conserved. Moreover, partial loss of maternal LSD1/KDM1A results in striking phenotypes weeks after fertilization; including perinatal lethality and abnormal behavior in surviving adults. These maternal effect hypomorphic phenotypes are associated with alterations in DNA methylation and expression at imprinted genes. These results establish a novel mammalian paradigm where defects in early epigenetic reprogramming can lead to defects that manifest later in development. DOI: http://dx.doi.org/10.7554/eLife.08848.001 PMID:26814574

  7. Assessment of non-carious root surface defects in areas of gingival recession: A descriptive study

    PubMed Central

    Jacob, Caroline-Annette; Nainar, Deepavalli-Arumuga

    2016-01-01

    Background The purpose of this descriptive study was to observe the distribution of four different classes of non-carious cervical root surface discrepancies in teeth with gingival recession. Additionally to explore the different treatment modalities in the literature for each of these defects. Material and Methods A total of 150 subjects with at least one labial gingival recession were included in the study. 1400 teeth were evaluated using 2.5 X magnification loupes and UNC -15 probe for the presence of the cemento-enamel junction and step like defects according to Pini-Prato’s classification: A-, identifiable CEJ without defect; A+, identifiable CEJ with defect; B-, unidentifiable CEJ without defect, B+, unidentifiable CEJ with defect. Further a comprehensive electronic and hand search of pubmed indexed journals was performed to identify appropriate treatment modalities for these defects and their predictability following restorative/surgical or combination of both. Results A total of 1400 teeth with exposed root surfaces were examined (793 Maxillary; 607 mandibular). 499 teeth were A-, 405 were A+, 322 were B+ and 174 were B-. The distribution of these defects in different teeth was: 36% premolars, 32% molars, 21% incisors and 11% canines, collectively 68% in the aesthetic zone. Conclusions Majority of these lesions are in the maxillary aesthetic zone. Hence the presence of the CEJ and the defect must be taken into account while managing these defects surgically. Key words:Cervical abrasion, gingival recession, magnification loupes, root coverage, step defects. PMID:27703607

  8. Tunable magnetic and electronic properties of BN nanosheets with triangular defects: a first-principles study.

    PubMed

    Wang, Yanli; Ding, Yi

    2014-10-29

    Experimentally, vacancy defects are commonly observed in BN nanosheets, expecially nitrogen-terminated triangular defects. Based on first-principles calculations, we systematically investigate the magnetic and electronic properties of BN nanosheets with these triangular vacancies (referred to as Vi(i = 1 - 4) defects with i representing the number of N atoms on each side of the triangle). It is found that the Vi defects bring diverse magnetic states into BN sheets, which are ferrimagnetic for V1, nonmagnetic for V2, ferrimagnetic for V3 and antiferromagnetic for V4 defects. When the isotropic strains are applied, the ferrimagnetic state is sustained for V1 defect, whereas the V2 defect undergoes a nonmagnetic to antiferromagnetic transition and the V3, V4 defects experience an abrupt change in the absolute magnetic moments under small strains, which are originated from the N-N bond breaking at these defects. Different from the BN nanoribbons, the antiparallel coupling is more favorable for the N atoms at the edges of triangular defects. Due to the triangular defects, the band gaps of BN sheets are reduced substantially, which could be further modulated by the strains. When the defective BN sheets serve as a substrate for graphene, the V1, V3 and V4 defects in BN would induce p-type doping in the graphene sheet. Interestingly, when the V2 defect is embedded in BN sheets, the doping behavior of graphene can be well-controlled by the strain, which is charge neutral at the strain-free state and p-type doped under strains. Our studies demonstrate that the rich magnetic and electronic properties of BN sheets with triangular defects enable the system's potential applications in nanodevices.

  9. Detecting gene-environment interactions in human birth defects: Study designs and statistical methods.

    PubMed

    Tai, Caroline G; Graff, Rebecca E; Liu, Jinghua; Passarelli, Michael N; Mefford, Joel A; Shaw, Gary M; Hoffmann, Thomas J; Witte, John S

    2015-08-01

    The National Birth Defects Prevention Study (NBDPS) contains a wealth of information on affected and unaffected family triads, and thus provides numerous opportunities to study gene-environment interactions (G×E) in the etiology of birth defect outcomes. Depending on the research objective, several analytic options exist to estimate G×E effects that use varying combinations of individuals drawn from available triads. In this study, we discuss important considerations in the collection of genetic data and environmental exposures. We will also present several population- and family-based approaches that can be applied to data from the NBDPS including case-control, case-only, family-based trio, and maternal versus fetal effects. For each, we describe the data requirements, applicable statistical methods, advantages, and disadvantages. A range of approaches can be used to evaluate potentially important G×E effects in the NBDPS. Investigators should be aware of the limitations inherent to each approach when choosing a study design and interpreting results. © 2015 Wiley Periodicals, Inc.

  10. Correlation between electron-irradiation defects and applied stress in graphene: A molecular dynamics study

    SciTech Connect

    Kida, Shogo; Yamamoto, Masaya; Kawata, Hiroaki; Hirai, Yoshihiko; Yasuda, Masaaki; Tada, Kazuhiro

    2015-09-15

    Molecular dynamics (MD) simulations are performed to study the correlation between electron irradiation defects and applied stress in graphene. The electron irradiation effect is introduced by the binary collision model in the MD simulation. By applying a tensile stress to graphene, the number of adatom-vacancy (AV) and Stone–Wales (SW) defects increase under electron irradiation, while the number of single-vacancy defects is not noticeably affected by the applied stress. Both the activation and formation energies of an AV defect and the activation energy of an SW defect decrease when a tensile stress is applied to graphene. Applying tensile stress also relaxes the compression stress associated with SW defect formation. These effects induced by the applied stress cause the increase in AV and SW defect formation under electron irradiation.

  11. Kinetic Defects Induced by Melittin in Model Lipid Membranes: A Solution Atomic Force Microscopy Study.

    PubMed

    Pan, Jianjun; Khadka, Nawal K

    2016-05-26

    Quantitative characterization of membrane defects (pores) is important for elucidating the molecular basis of many membrane-active peptides. We study kinetic defects induced by melittin in vesicular and planar lipid bilayers. Fluorescence spectroscopy measurements indicate that melittin induces time-dependent calcein leakage. Solution atomic force microscopy (AFM) is used to visualize melittin-induced membrane defects. After initial equilibration, the most probable defect radius is ∼3.8 nm in 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) bilayers. Unexpectedly, defects become larger with longer incubation, accompanied by substantial shape transformation. The initial defect radius is ∼4.7 nm in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. Addition of 30 mol % cholesterol to DOPC bilayers suppresses defect kinetics, although the inhibitory impact is negated by longer incubation. Overall, the kinetic rate of defect development follows DLPC > DOPC > DOPC/cholesterol. Kinetic defects are also observed when anionic lipids are present. Based on the observation that defects can occupy as large as 40% of the bilayer surface, we propose a kinetic defect growth model. We also study the effect of melittin on the phase behavior of DOPC/egg-sphingomyelin/cholesterol bilayers. We find that melittin initially suppresses or eliminates liquid-ordered (Lo) domains; Lo domains gradually emerge and become the dominant species with longer incubation; and defects in phase-coexisting bilayers have a most probable radius of ∼5 nm and are exclusively localized in the liquid-disordered (Ld) phase. Our experimental data highlight that melittin-induced membrane defects are not static; conversely, spontaneous defect growth is intrinsically associated with membrane permeabilization exerted by melittin.

  12. Knowledge and periconceptional use of folic acid for the prevention of neural tube defects in ethnic communities in the United Kingdom: systematic review and meta-analysis.

    PubMed

    Peake, Jordana N; Copp, Andrew J; Shawe, Jill

    2013-07-01

    It is widely accepted that periconceptional supplementation with folic acid can prevent a significant proportion of neural tube defects (NTDs). The present study evaluated how folic acid knowledge and periconceptional use for NTD prevention varies by ethnicity in the United Kingdom (U.K.). A literature search was conducted to identify studies that included assessment of folic acid knowledge or use in U.K. women of different ethnicities. Only research and referenced sources published after 1991, the year of the landmark Medical Research Council's Vitamin Study, were included. A meta-analysis was performed of studies that assessed preconceptional folic acid use in Caucasians and non-Caucasians. Five studies met the inclusion criteria for assessment of knowledge and/or use of folic acid supplements in U.K. women including non-Caucasians. The available evidence indicates that South Asians specifically have less knowledge and lower periconceptional use of folic acid than Caucasians; one study found that West Indian and African women also had lower folic acid uptake. A synthesis of results from three of the studies, in a meta-analysis, shows that Caucasians are almost three times more likely to take folic acid before conception than non-Caucasians. From the limited evidence available, U.K. women of non-Caucasian ethnicity appear to have less knowledge and a lower uptake of folic acid supplementation than Caucasians during the periconceptional period. Implementing targeted, innovative education campaigns together with a mandatory fortification policy, including the fortification of ethnic minority foods, will be required for maximum prevention of folic acid-preventable NTDs across different ethnic groups. Copyright © 2013 Wiley Periodicals, Inc.

  13. Laser annealing and defect study of chalcogenide photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Bhatia, Ashish

    Cu(In,Ga)Se2 (CIGSe), CuZnSn(S,Se)4(CZTSSe), etc., are the potential chalcogenide semiconductors being investigated for next-generation thin film photovoltaics (TFPV). While the champion cell efficiency of CIGSe has exceeded 20%, CZTSSe has crossed the 10% mark. This work investigates the effect of laser annealing on CISe films, and compares the electrical characteristics of CIGSe (chalcopyrite) and CZTSe (kesterite) solar cells. Chapter 1 through 3 provide a background on semiconductors and TFPV, properties of chalcopyrite and kesterite materials, and their characterization using deep level transient spectroscopy (DLTS) and thermal admittance spectroscopy (TAS). Chapter 4 investigates electrochemical deposition (nonvacuum synthesis) of CISe followed by continuous wave laser annealing (CWLA) using a 1064 nm laser. It is found that CWLA at ≈ 50 W/cm2 results in structural changes without melting and dewetting of the films. While Cu-poor samples show about 40% reduction in the full width at half maximum of the respective x-ray diffraction peaks, identically treated Cu-rich samples register more than 80% reduction. This study demonstrates that an entirely solid-phase laser annealing path exists for chalcopyrite phase formation and crystallization. Chapter 5 investigates the changes in defect populations after pulse laser annealing in submelting regime of electrochemically deposited and furnace annealed CISe films. DLTS on Schottky diodes reveal that the ionization energy of the dominant majority carrier defect state changes nonmonotonically from 215+/-10 meV for the reference sample, to 330+/-10 meV for samples irradiated at 20 and 30 mJ/cm2, and then back to 215+/-10 meV for samples irradiated at 40 mJ/cm2. A hypothesis involving competing processes of diffusion of Cu and laser-induced generation of In vacancies may explain this behavior. Chapter 6 compares the electrical characteristics of chalcopyrite and kesterite materials. Experiments reveal CZTSe cell has an

  14. Supplemental vitamin A prevents the acute radiation-induced defect in wound healing

    SciTech Connect

    Levenson, S.M.; Gruber, C.A.; Rettura, G.; Gruber, D.K.; Demetriou, A.A.; Seifter, E.

    1984-10-01

    Acute radiation injury leads to thymic involution, adrenal enlargement, leukopenia, thrombocytopenia, gastrointestinal ulceration, and impaired wound healing. The authors hypothesized that supplemental vitamin A would mitigate these adverse effects in rats exposed to acute whole-body radiation. To test their hypothesis, dorsal skin incisions and subcutaneous implantation of polyvinyl alcohol sponges were performed in anesthetized Sprague-Dawley rats at varying times following sham radiation or varying doses of whole-body radiation (175-850 rad). In each experiment, the control diet (which contains about 18,000 IU vit. A/kg chow (3 X the NRC RDA for normal rats)) was supplemented with 150,000 IU vit. A/kg diet beginning at, before, or after sham radiation and wounding or radiation and wounding. The supplemental vitamin A prevented the impaired wound healing and lessened the weight loss, leukopenia, thrombocytopenia, thymic involution, adrenal enlargement, decrease in splenic weight, and gastric ulceration of the radiated (750-850 rad) wounded rats. This was true whether the supplemental vitamin A was begun before (2 or 4 days) or after (1-2 hours to 4 days) radiation and wounding; the supplemental vitamin A was more effective when started before or up to 2 days after radiation and wounding. The authors believe that prevention of the impaired wound healing following radiation by supplemental vitamin A is due to its enhancing the early inflammatory reaction to wounding, including increasing the number of monocytes and macrophages at the wound site; possible effect on modulating collagenase activity; effect on epithelial cell (and possible mesenchymal cell) differentiation; stimulation of immune responsiveness; and lessening of the adverse effects of radiation.

  15. Defective Insulin Signalling, Mediated by Inflammation, Connects Obesity to Alzheimer Disease; Relevant Pharmacological Therapies and Preventive Dietary Interventions.

    PubMed

    Rodriguez-Casado, Arantxa; Toledano-Díaz, Adolfo; Toledano, Adolfo

    2017-01-01

    Recent evidence suggests that obesity, besides being a risk factor for cardiovascular events, also increases the risk of Alzheimer's disease. Insulin resistance is common in all cases of obesity and appears to be the linkage between both diseases. Obesity, often associated with excessive fat and sugar intake, represents a preclinical stage toward insulin resistance during which nutrition intervention is likely to have maximum effect. In this way, healthy lifestyles lifetime to prevent obesity-related modifiable risk factors such as inflammation, oxidative stress and metabolic disorders could be simultaneously beneficial for preserving cognition and controlling the Alzheimer's disease. This review relates extensive research literature on facts linking nutrients and dietary patterns to obesity and Alzheimer's disease. In addition briefly presents molecular mechanisms involved in obesity- induced insulin resistance and the contribution of peripheral inflammatory and defective insulin signalling pathways, as well as ectopic lipids accumulation to Alzheimer's development through brain inflammation, neuronal insulin resistance, and cognitive dysfunction seen in Alzheimer's disease. The work relates current and emerging pharmacological and non-pharmacological therapies for the management of obesity, insulin resistance and Alzheimer's considering them as disorders with common molecular features. The findings of this review validate the importance of some nutritional interventions as possible approach to prevent or delay simultaneously progression of Alzheimer's disease and obesity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. A study on limb reduction defects in six European regions.

    PubMed

    Stoll, C; Calzolari, E; Cornel, M; Garcia-Minaur, S; Garne, E; Nevin, N; Ten Kate, L

    1996-01-01

    Limb reduction defects (LRD) gained special attention after the thalidomide tragedy in 1962. LRD are common congenital malformations which present as obvious congenital anomalies recognized at birth. Therefore it might be assumed that they are well documented. However classification of LRDs is disputed as the identification of the exact site of the reduction(s) is hindered by imprecise information. This study was undertaken in 6 European countries to evaluate the use of the new classification proposed by EUROCAT for the epidemiologic and genetic study of LRD. The total number of births including livebirths, still-births and terminations, surveyed during 7 years by the 6 registries of congenital anomalies participating to this study was 611.150. The total prevalence of LRD was 7.06 per 10.000 births including the following categories prevalence : terminal transverse, 3.97, longitudinal, 1.75, proximal-intercalary, 0.10, split hand/foot 0.54 and multiple types 0.70. The prevalence of LRD was statistically higher in Basque Country, Odense, Strasbourg and Groningen than in Belfast and Emilia Romagna. Six per cent of the cases were chromosomal anomalies, including 15 trisomies 18 out of 26 cases, 49.5% (201 cases) were isolated LRD and 50.5% (206 cases) had other major non LRD associated malformations. Sex ratio and maternal age were not statistically different between regions and from the normal population. Multiply malformed with LRD had statistically significantly lower birthweight and lower gestational age than isolated cases with LRD, where available prenatal detection of LRD was higher in multiple malformed children with LRD than in isolated cases, 19.9% and 4.8% respectively. The precurrence risk was 1 in 37.

  17. Observed Prevalence of Congenital Heart Defects From a Surveillance Study in China

    PubMed Central

    Zhang, Yali; Riehle-Colarusso, Tiffany; Correa, Adolfo; Li, Song; Feng, Xinheng; Gindler, Jacqueline; Lin, Hui; Webb, Catherine; Li, Wei; Trines, Jean; Berry, Robert J.; Yeung, Lorraine; Luo, Ying; Jiang, Meifang; Chen, Hua; Sun, Xiamei; Li, Zhu

    2015-01-01

    Objectives The purpose of this study was to estimate the prevalence of major and minor congenital heart defects among fetuses and neonates using sonography in a general population of 4 areas surrounding Shanghai, China. Methods Pregnant women were recruited between April 2004 and December 2005 in Jiaxing City, Suzhou City, Changshu County, and Haining County. All participants could have 3 sonographic examinations performed by specially trained physicians regardless of medical indication: a fetal sonographic screen and fetal echocardiography between 20 and 28 weeks’ gestation and neonatal echocardiography. Diagnoses of congenital heart defects were made on the basis of review of all available scans by an international group of experts in pediatric cardiology. Prevalence rates were calculated per 1000 births. Results Among 4006 scanned fetuses and neonates, there were 75 congenital heart defects, including 12 major defects. The observed prevalence for all congenital heart defects was 18.7 (95% confidence interval, 14.8–23.5) per 1000 births, and the prevalence for major defects was 3.0 (95% confidence interval, 1.6–5.2) per 1000 births. The most common defects were ventricular septal defects (n = 47 [62.7%]), atrial septal defects (n = 14 [18.7%]), tetralogy of Fallot (n = 4 [5.3%]), and hypoplastic left heart syndrome (n = 3 [4.0%]). Conclusions The prevalence of all congenital heart defects in the 4 areas of China studied was higher than that reported in other countries, with ventricular septal defects being the most frequent defects. Our data likely reflect a better estimate of the total prevalence of congenital heart defects in China than reported previously. PMID:21705732

  18. Preventing dental caries: part 2. Case studies in prevention.

    PubMed

    Blinkhorn, Anthony S; Davies, Robin M

    2013-12-01

    This article seeks to bring together the preventive messages given in Paper 1 and apply them to specific individual patients. The key elements are the appropriate advice on fluorides, fissure sealants, diet and formulating advice in terms of an individual's educational background. This article offers practical advice on the prevention of dental caries using individual patient-based scenarios.

  19. Folic acid supplementation influences the distribution of neural tube defect subtypes: A registry-based study.

    PubMed

    Bergman, J E H; Otten, E; Verheij, J B G M; de Walle, H E K

    2016-01-01

    Periconceptional folic acid (FA) reduces neural tube defect (NTD) risk, but seems to have a varying effect per NTD subtype. We aimed to study the effect of FA supplementation on NTD subtype distribution using data from EUROCAT Northern Netherlands. We included all birth types with non-syndromal NTDs born in 1997-2012. By Fisher's exact test we analyzed possible differences in NTD subtype distribution between a correct FA supplementation group and incorrect FA supplementation group. We found proportionally fewer cervical/thoracic spina bifida cases and more lumbar/sacral spina bifida cases in the correct FA supplementation group, irrespective of the presence of the main NTD risk factors. The effect on NTD subtype distribution was only seen when FA supplementation was started before conception. We conclude that FA not only prevents the occurrence of a significant proportion of NTDs, but might also decrease the severity of NTDs, as long as supplementation is started before conception.

  20. Repair of bone defects with absorbable membranes. A study on rabbits.

    PubMed

    Ashammakhi, N; Mäkelä, E A; Vihtonen, K; Rokkanen, P; Törmälä, P

    1995-01-01

    Self-reinforced polyglycolic acid (SR-PGA) devices were developed in the mid-eighties, applied for fixation purposes and proved to be biocompatible. In this study SR-PGA membranes (10 x 10 mm) were used to augment defects on the medial aspect of distal femoral metaphysis in 31 New Zealand rabbits. Defects of 3.5 mm were either filled with autografts or left non-grafted. In a control group, no membranes were used. The rabbits were followed up for six, 12 and 24 weeks. Radiography, histology, oxytetracycline (OTC) fluorescence labelling and microradiography were used. Defects where membranes were used, healed by new bone formation. In some cases where polyglycolic acid (PGA) membranes were not used, defects were invaded by fibrous tissue. Membranes sometimes slipped away from their positions opposite to grafted defects. This study proved that the advantage of the use of PGA membranes could be taken in augmentation of cancellous bone defects in rabbits.

  1. Lithium-ion drifting: Application to the study of point defects in floating-zone silicon

    NASA Technical Reports Server (NTRS)

    Walton, J. T.; Wong, Y. K.; Zulehner, W.

    1997-01-01

    The use of lithium-ion (Li(+)) drifting to study the properties of point defects in p-type Floating-Zone (FZ) silicon crystals is reported. The Li(+) drift technique is used to detect the presence of vacancy-related defects (D defects) in certain p-type FZ silicon crystals. SUPREM-IV modeling suggests that the silicon point defect diffusivities are considerably higher than those commonly accepted, but are in reasonable agreement with values recently proposed. These results demonstrate the utility of Li(+) drifting in the study of silicon point defect properties in p-type FZ crystals. Finally, a straightforward measurement of the Li(+) compensation depth is shown to yield estimates of the vacancy-related defect concentration in p-type FZ crystals.

  2. Defective TGFβ signaling in bone marrow-derived cells prevents Hedgehog-induced skin tumors

    PubMed Central

    Liu, Hailan; Yang, Ling; Zhang, Xiaoli; Yoder, Mervin C.; Kaplan, Mark H.; Xie, Jingwu

    2013-01-01

    Hedgehog (Hh) signaling in cancer cells drives changes in the tumor microenvironment that are incompletely understood. Here we report that Hh- driven tumors exhibit an increase in myeloid-derived suppressor cells (MDSC) and a decrease in T cells, indicative of an immune suppressive tumor microenvironment. This change was associated with activated TGFβ signaling in several cell types in BCCs. We determined that TGFβ signaling in bone marrow (BM)-derived cells, not keratinocytes, regulates MDSC and promotes tumor development. Tgfbr2 deficiency in the BM-derived cells also reduced the size of previously developed tumors in mice. We identified CCL2 as the major chemokine attracting MDSC to tumor, whose expression was Tgfbr2-dependent, whereas its receptor CCR2 was highly expressed in MDSC population. CCL2 alone was sufficient to induce migration of MDSC. Moreover, the CCR2 inhibitors prevented MDSC migration towards skin cells in vitro, reduced MDSC accumulation and Hh signaling-driven tumor development in mice. Our results reveal a signaling network critical for Hh signaling in cancer cells to establish an effective immune suppressive microenvironment during tumor development. PMID:24282281

  3. [Prevention of neural tube defects: prevalence of folic acid supplementation during pregnancy and associated factors in Pelotas, Rio Grande do Sul State, Brazil].

    PubMed

    Mezzomo, Cíntia Leal Sclowitz; Garcias, Gilberto de Lima; Sclowitz, Marcelo Leal; Sclowitz, Iandora Timm; Brum, Clarice Brinck; Fontana, Tiago; Unfried, Ricardo Issler

    2007-11-01

    To determine folic acid use and associated factors, a cross-sectional population-based study was conducted in all five maternity hospitals in Pelotas, Rio Grande do Sul State, Brazil. Data were collected from April 1 to August 15, 2006 (n = 1,450 women). A standard questionnaire was applied in the hospitals. Statistical analysis used Poisson regression. Prevalence of folic acid consumption during pregnancy was 31.8%, and periconceptional use was 4.3%. The following were associated with folic acid use: white skin color, schooling > 9 years, family income > R$600, age > 30 years, planned pregnancy, > or =7 prenatal visits, knowledge on folic acid, and prenatal care in the private health system. In order to prevent neural tube defects, it is important to promote folic acid use among childbearing-age women and to supply folic acid to poor women.

  4. Prevention of Aerobic Spoilage of Maize Silage by a Genetically Modified Killer Yeast, Kluyveromyces lactis, Defective in the Ability To Grow on Lactic Acid

    PubMed Central

    Kitamoto, H. K.; Hasebe, A.; Ohmomo, S.; Suto, E. G.; Muraki, M.; Iimura, Y.

    1999-01-01

    In this study, we propose a new process of adding a genetically modified killer yeast to improve the aerobic stability of silage. Previously constructed Kluyveromyces lactis killer strain PCK27, defective in growth on lactic acid due to disruption of the gene coding for phosphoenolpyruvate carboxykinase, a key enzyme for gluconeogenesis, inhibited the growth of Pichia anomala inoculated as an aerobic spoilage yeast and prevented a rise in pH in a model of silage fermentation. This suppressive effect of PCK27 was not only due to growth competition but also due to the killer protein produced. From these results, we concluded that strain PCK27 can be used as an additive to prolong the aerobic stability of maize silage. In the laboratory-scale experiment of maize silage, the addition of a killer yeast changed the yeast flora and significantly reduced aerobic spoilage. PMID:10508111

  5. C-V and DLTS studies of radiation induced Si-SiO2 interface defects

    NASA Astrophysics Data System (ADS)

    Capan, I.; Janicki, V.; Jacimovic, R.; Pivac, B.

    2012-07-01

    Interface traps at the Si-SiO2 interface have been and will be an important performance limit in many (future) semiconductor devices. In this paper, we present a study of fast neutron radiation induced changes in the density of Si-SiO2 interface-related defects. Interface related defects (Pb centers) are detected before and upon the irradiation. The density of interface-related defects is increasing with the fast neutron fluence.

  6. Vandalism Prevention Programs: A Case Study Approach.

    ERIC Educational Resources Information Center

    White, James; Fallis, Anita

    The objective of this study was to identify, describe, and appraise existing behavior-oriented, vandalism-prevention programs using a case-study approach. This report summarizes an investigation of three programs in Ontario (Canada): Project PRIDE (Pupils Responsible in Determining their own Environment); Operation Aware; and a Diversion program.…

  7. First principles study of O defects in CdSe

    NASA Astrophysics Data System (ADS)

    T-Thienprasert, J.; Limpijumnong, S.; Du, M.-H.; Singh, D. J.

    2012-08-01

    Recently, the vibrational signatures related to oxygen defects in oxygen-doped CdSe were measured using ultrahigh resolution Fourier transform infrared (FTIR) spectroscopy by Chen et al.(2008) [1]. They observed two absorption bands centered at ∼1991.77 and 2001.3 cm-1, which they attributed to the LVMs of OCd, in the samples grown with the addition of CdO and excess Se. For the samples claimed to be grown with even more excess Se, three high-frequency modes (1094.11, 1107.45, and 1126.33) were observed and assigned to the LVMs of OSe-VCd complex. In this work, we explicitly calculated the vibrational signatures of OCd and OSe-VCd complex defects based on first principles approach. The calculated vibrational frequencies of OCd and OSe-VCd complex are inconsistent with the frequencies observed by Chen et al., indicating that their observed frequencies are from other defects. Potential defects that could explain the experimentally observed modes are suggested.

  8. A DFT study of Cu nanoparticles adsorbed on defective graphene

    NASA Astrophysics Data System (ADS)

    García-Rodríguez, D. E.; Mendoza-Huizar, L. H.; Díaz, C.

    2017-08-01

    Metal nanoparticles adsorbed on graphene are systems of interest for processes relative to catalytic reactions and alternative energy production. Graphene decorated with Cu-nanoparticles, in particular, could be a good alternative material for electrodes in direct borohydride fuel cells. However our knowledge of this system is still very limited. Based on density functional theory, we have analyzed the interaction of Cun nanoparticles (n = 4, 5, 6, 7, 13) with pristine and defective-graphene. We have considered two types of defects, a single vacancy (SV), and an extended lineal structural defect (ELSD), formed by heptagon-pentagon pairs. Our analysis has revealed the covalent character of the Cun-graphene interaction for pristine- and ELSD-graphene, and a more ionic-like interaction for SV-graphene. Furthermore, our analysis shows that the interaction between the nanoparticles and the graphene is rather local, i.e., only the nanoparticle atoms close to the contact region are involved in the interaction, being the electronic contact region much higher for defective-graphene than for pristine-graphene. Thus, the higher the particle the lower its average electronic and structural distortion.

  9. Remaining Visual Field and Preserved Subjective Visual Functioning Prevent Mental Distress in Patients with Visual Field Defects

    PubMed Central

    Gall, Carolin; Brösel, Doreen; Sabel, Bernhard A.

    2013-01-01

    Background: Patients with visual field defects after visual pathway lesion may experience reduced vision-related quality of life (vrQoL). It has not been clarified how vrQoL impairments contribute to vision-related mental distress. Methods: One hundred and eight subjects with visual field defects caused by optic neuropathies (age M = 57.6; SD = 13.7 years) answered the National Eye Institute Visual-Functioning Questionnaire 39 (NEI-VFQ) for vrQoL and the SF-12 Short Form Health Survey for health-related quality of life. A 10 item composite of NEI-VFQ “visual functioning” and 5 items of “mental-health symptoms due to vision problems” were subjected to Rasch analysis. The test battery comprised static and High Resolution Perimetry (HRP). Regression and path analysis were used to investigate associations between QoL, mental distress, and perimetry results. Results: A higher level of “visual functioning” was associated with monocular impairment and a larger remaining visual field compared to binocular impairment. Subjective “visual functioning” but not visual field parameters predicted “mental-health symptoms due to vision problems” which was the only variable associated with the SF-12 mental component score. The SF-12 physical component score was less strongly associated with “mental-health symptoms due to vision problems.” Here, reaction time in HRP and mean threshold in perimetry were additional significant variables. Path analysis revealed a significant path from remaining visual field via visual functioning on mental health. Conclusion: Subjective consequences of visual impairments in everyday life impact mental health rather than “objective” visual function loss as measured by perimetry. Since a higher extent of vrQoL was related to lower levels of mental distress, the maintenance of vrQoL could reduce and prevent mental distress due to vision problems. Patients with persisting visual field defects may benefit from

  10. Intrinsic defect in BiNbO4: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Lai, Kangrong; Zhu, Yingtao; Dai, Ying; Huang, Baibiao

    2012-08-01

    Formation energies, transition energy levels, and electronic properties of various intrinsic defects in BiNbO4 systems are studied based on the first-principles density-functional theory. Our results indicate that the acceptor defects form easier than donor defects under O rich condition, while it is opposite under Bi rich condition. Under O-rich condition, Bi vacancies (Bivac) leading to p-type conductivity are the dominant intrinsic defects, whereas O vacancies (Ovac) inducing moderate n-type conductivity are the dominant intrinsic defects under Bi-rich condition. Among these intrinsic defects, Ovac is a deep donor; to the contrary, Bivac is found to be a shallow acceptor which is benefit to the separation and migration of the photogenerated carriers. Consequently, the BiNbO4 with Bivac under O-rich growth condition should be of better photocatalytic performance.

  11. A Study on the Effects of Ball Defects on the Fatigue Life in Hybrid Bearings

    NASA Technical Reports Server (NTRS)

    Tang, Ching-Yao; Foerster, Chad E.; O'Brien, Michael J.; Hardy, Brian S.; Goyal, Vinay K.; Nelson, Benjamin A.; Robinson, Ernest Y.; Ward, Peter C.; Hilton, Michael R.

    2014-01-01

    Hybrid ball bearings using silicon nitride ceramic balls with steel rings are increasingly being used in space mechanism applications due to their high wear resistance and long rolling contact fatigue life. However, qualitative and quantitative reports of the effects of ball defects that cause early fatigue failure are rare. We report on our approach to study these effects. Our strategy includes characterization of defects encountered in use, generation of similar defects in a laboratory setting, execution of full-scale bearing tests to obtain lifetimes, post-test characterization, and related finite-element modeling to understand the stress concentration of these defects. We have confirmed that at least one type of defect of appropriate size can significantly reduce fatigue life. Our method can be used to evaluate other defects as they occur or are encountered.

  12. Study on distortion correction for image mosaic of surface defects

    NASA Astrophysics Data System (ADS)

    Wang, Shitong; Liu, Dong; Chen, Xiaoyu; Cao, Pin; Yang, Yongying

    2012-10-01

    It is hard to quantitate the micron-scale defects on large aperture (102mm×102mm) optical components by the conventional optical testing methods. This paper proposes a super-smooth surface defects measurement and evaluation system, achieved by using microscopic dark-field scattering imaging device, two-dimensional sub-image scanning mechanism and multi-cycle image mosaic algorithm. The defects detecting system, with a lateral resolution of 0.5μm, applies a large field of view design (largest FOV: 15mm×15mm). In order to test the largest element (430mm×430mm), however, over 1000 sub-pictures are captured. It takes more than 30 minutes to process these sub-pictures by multi-cycle image mosaic algorithm. This paper also presents a distortion correction method to revise the image mosaic mismatch caused by the optical distortion in the defects testing system on the platform of MATLAB. A binary optical grid plate (BOE) is fabricated as standard board to evaluate distortion. The proposed method applies image division multi-steps to build a look-up matrix of distortion parameters. According to the look-up matrix, all pixels on a sub-image are repositioned from the distortion Cartesian coordinates to the ideal Cartesian coordinates. Finally, feasibility of the distortion correction method is demonstrated by comparing the mosaic results of defect images before and after this process. The full field view distortion is reduced from more than 4% to less than 0.1%. After distortion correction, subimages can be directly mosaicked without using multi-cycle image mosaic algorithm, which improves test efficiency significantly. The method mentioned in this paper may also apply to other optical testing systems for image mosaic.

  13. Laser Scattering Tomography for the Study of Defects in Protein Crystals

    NASA Technical Reports Server (NTRS)

    Feigelson, Robert S.; DeLucas, Lawrence; DeMattei, R. C.

    1997-01-01

    The goal of this research is to explore the application of the non-destructive technique of Laser Scattering Tomography (LST) to study the defects in protein crystals and relate them to the x-ray diffraction performance of the crystals. LST has been used successfully for the study of defects in inorganic crystals and. in the case of lysozyme, for protein crystals.

  14. Developing effective campaign messages to prevent neural tube defects: a qualitative assessment of women's reactions to advertising concepts.

    PubMed

    Massi Lindsey, Lisa L; Silk, Kami J; Von Friederichs-Fitzwater, Marlene M; Hamner, Heather C; Prue, Christine E; Boster, Franklin J

    2009-03-01

    The incidence of neural tube defects (NTDs), serious birth defects of the brain and spine that affect approximately 3,000 pregnancies in the United States each year, can be reduced by 50-70% with daily periconceptional consumption of the B vitamin folic acid. Two studies were designed to assess college women's reactions to and perceptions of potential campaign advertising concepts derived from preproduction formative research to increase folic acid consumption through the use of a daily multivitamin. Study one assessed draft advertising concepts in eight focus groups (N = 71) composed of college-enrolled women in four cities geographically dispersed across the United States. Based on study one results, the concepts were revised and reassessed in study two with a different sample (eight focus groups; N = 73) of college women in the same four cities. Results indicated that participants generally responded favorably to concepts in each of the two studies, and provided insight into individual concepts to increase their overall appeal and effectiveness. The specific findings and implications of these results are discussed.

  15. Structural transformations from point to extended defects in silicon: A molecular dynamics study

    SciTech Connect

    Marques, Luis A.; Pelaz, Lourdes; Santos, Ivan; Lopez, Pedro; Aboy, Maria

    2008-11-15

    We use classical molecular dynamics simulation techniques to study how point defects aggregate to form extended defects in silicon. We have found that <110> chains of alternating interstitials and bond defects, a generalization of the Si di-interstitial structure, are metastable at room temperature but spontaneously transform into (311) defects when annealed at higher temperatures. Obtained atomic configurations and energetics are in good agreement with experiments and previous theoretical calculations. We have found a (311) structural unit which consists of two interstitial chains along <110> but arranged differently with respect to the known (311) units.

  16. Maternal and perinatal aspects of birth defects: a case-control study

    PubMed Central

    Nhoncanse, Geiza César; Germano, Carla Maria R.; de Avó, Lucimar Retto da S.; Melo, Débora Gusmão

    2014-01-01

    Objective: To assess the prevalence of congenital defects and to investigate their maternal and perinatal associated aspects by reviewing Birth Certificates. Methods: Among all born alive infants from January 2003 to December 2007 in Maternidade da Santa Casa de Misericórdia of São Carlos, Southeast Brazil (12,199 infants), cases were identified as the newborns whose Birth Certificates registered any congenital defect. The same sex neonate born immediately after the case was chosen as a control. In total, 13 variables were analyzed: six were maternal related, three represented labor and delivery conditions and four were linked to fetal status. The chi-square and Fisher's exact tests were used to compare the variables, being significant p<0.05. Results: The prevalence of congenital defects was 0.38% and the association of two or more defects represented 32% of all cases. The number of mothers whose education level was equal or less than eight years was significantly higher among the group with birth defects (p=0.047). A higher frequency of prematurity (p<0.001) and cesarean delivery (p=0.004) was observed among children with birth defects. This group also showed lower birth weight and Apgar scores in the 1st and the 5th minute (p<0.001). Conclusions: The prevalence of congenital defect of 0.38% is possibly due to underreporting. The defects notified in the Birth Certificates were only the most visible ones, regardless of their severity. There is a need of adequate epidemiological monitoring of birth defects in order to create and expand prevention and treatment programs. PMID:24676186

  17. Associations of birth defects with adult intellectual performance, disability and mortality: population-based cohort study.

    PubMed

    Eide, Martha G; Skjaerven, Rolv; Irgens, Lorentz M; Bjerkedal, Tor; Oyen, Nina

    2006-06-01

    Infants born with birth defects have poorer outcomes in terms of mortality and disability, but the long-term intellectual outcome in children with birth defects is generally unknown. We assessed the long-term associations of various birth defects with mortality and disability, and evaluated whether high mortality and disability were reflected in impaired intellectual performance at age 18. In this nationwide cohort study, records of 9,186 males with and 384,384 without birth defects, registered in the Medical Birth Registry of Norway (1967-1979) were linked to the National Conscript Service (1984-1999). Mortality and disability before military draft, and intelligence test score at conscription were the main outcome measures. Males with birth defects had a relative risk for disability of 6.0 compared with males without defects. Disability was low within categories of birth defects associated with low mortality, and high within defect categories associated with high mortality. The relative risk for not being drafted was highest if maternal educational level was low. Heart defects and cleft palate were the only subgroups in which intellectual performance was lower after adjustment for maternal education, maternal age, marital status and birth order. In particular, intellectual performance was not impaired among those with multiple compared with single defects. We conclude that for the majority of birth defect categories in the present birth cohort, our hypothesis that intellectual performance would be impaired was not confirmed. Thus, there seems to be little reason to fear an adverse intellectual outcome in non-disabled surviving infants with birth defects.

  18. Quantum defect orbital study of the sodium isoelectronic sequence

    NASA Astrophysics Data System (ADS)

    Martin, Inmaculada; Karwowski, Jacek; Lavin, Carmen; Diercksen, Geerd H. F.

    1991-12-01

    The quantum defect orbital (QDO) method and its relativistic (RQDO) counterpart have been applied to the calculation of oscillator strengths for the 3s 2S → 3p 2Po, 3p 2Po → 3d 2D, 3d 2D → 4f 2Fo, and 3d 2D → 5f 2Fo transitions in sodium-like atoms. The consequences of including relativistic effects are demonstrated.

  19. Formate supplementation enhances folate-dependent nucleotide biosynthesis and prevents spina bifida in a mouse model of folic acid-resistant neural tube defects.

    PubMed

    Sudiwala, Sonia; De Castro, Sandra C P; Leung, Kit-Yi; Brosnan, John T; Brosnan, Margaret E; Mills, Kevin; Copp, Andrew J; Greene, Nicholas D E

    2016-07-01

    The curly tail mouse provides a model for neural tube defects (spina bifida and exencephaly) that are resistant to prevention by folic acid. The major ct gene, responsible for spina bifida, corresponds to a hypomorphic allele of grainyhead-like 3 (Grhl3) but the frequency of NTDs is strongly influenced by modifiers in the genetic background. Moreover, exencephaly in the curly tail strain is not prevented by reinstatement of Grhl3 expression. In the current study we found that expression of Mthfd1L, encoding a key component of mitochondrial folate one-carbon metabolism (FOCM), is significantly reduced in ct/ct embryos compared to a partially congenic wild-type strain. This expression change is not attributable to regulation by Grhl3 or the genetic background at the Mthfd1L locus. Mitochondrial FOCM provides one-carbon units as formate for FOCM reactions in the cytosol. We found that maternal supplementation with formate prevented NTDs in curly tail embryos and also resulted in increased litter size. Analysis of the folate profile of neurulation-stage embryos showed that formate supplementation resulted in an increased proportion of formyl-THF and THF but a reduction in proportion of 5-methyl THF. In contrast, THF decreased and 5-methyl THF was relatively more abundant in the liver of supplemented dams than in controls. In embryos cultured through the period of spinal neurulation, incorporation of labelled thymidine and adenine into genomic DNA was suppressed by supplemental formate, suggesting that de novo folate-dependent biosynthesis of nucleotides (thymidylate and purines) was enhanced. We hypothesise that reduced Mthfd1L expression may contribute to susceptibility to NTDs in the curly tail strain and that formate acts as a one-carbon donor to prevent NTDs.

  20. Defectivity study of directed self-assembly of cylindrical diblock copolymers in laterally confined thin channels

    NASA Astrophysics Data System (ADS)

    Kim, Bongkeun; Laachi, Nabil; Fredrickson, Glenn H.

    2013-03-01

    We use self-consistent field theory (SCFT) to study the directed self-assembly of cylinder-forming diblock copolymers laterally confined in narrow channels. The side walls and top/bottom surfaces of the channel are either all major block attractive, all minor block attractive, or a combination of major block attractive on the top surface and minor block attractive on the remaining film surfaces. We focus on systems in which the self-assembled cylinders form a monolayer oriented parallel to the sidewalls in a thin channel. Experimentally and theoretically, well-ordered perfect cylinders are observed in narrow channels, but undesirable defective structures are also found. We investigate the energetics of isolated, meta-stable defects and compare them with two types of defects (dislocations and disclinations) recently investigated in laterally confined lamellar block copolymer systems using SCFT. Our simulation results are also compared with defect energy estimates for lying down cylinder monolayers extracted from experimental work by Mishra and coworkers. Parametric studies include the effects of film thickness, domain spacing, χN, and composition on defect energies with various wall wetting conditions in narrow channels of varying widths. A major finding is that defects of cylindrical directed self-assembly in a confined channel have a smaller free energy cost (tens of kT) in comparison with defects in laterally confined, vertically oriented lamellae (many tens of kT). We also discovered a novel vertically branched cylinder defect in the case of neutral top and bottom surfaces with significantly lower defect energy than a corresponding dislocation defect. More broadly, this study reveals unexpected dependences of equilibrium defect densities on a wide range of parameters that must be carefully controlled in order to successfully implement a directed self-assembly process with block-copolymers.

  1. Studies on the Protein Defect in Tangier Disease

    PubMed Central

    Lux, Samuel E.; Levy, Robert I.; Gotto, Antonio M.; Fredrickson, Donald S.

    1972-01-01

    High density lipoproteins (d 1.063-1.210 g/ml) were isolated from the plasma of normal individuals (HDL) and seven homozygous patients with Tangier disease (HDLt). In Tangier patients, the concentration of protein in the high density region (HDLt) was only 0.5-4.5% of normal. Immunochemical studies, including mixing experiments conducted in vivo and in vitro, indicated that HDLt was different from HDL. HDLt was the only high density lipoprotein detectable in the plasma of Tangier homozygotes. In heterozygotes both HDL and HDLt were present. HDLt was not detected in the plasma of over 300 normal persons and 10 patients with secondary high density lipoprotein deficiency and appeared to be a unique marker for Tangier disease. ApoHDL contained two major apoproteins designated apoLp-Gln-I and apoLp-Gln-II; together they comprised 85-90% of the total protein content. Both of the major HDL apoproteins were present in apoHDLt; but apoLp-Gln-I was disproportionately decreased with respect to apoLp-Gln-II, the ratio of their concentrations being 1: 12 in apoHDLt as compared with 3: 1 in apoHDL. Several minor apoprotein components which together comprise 5-15% of apoHDL were present in approximately normal proportions in apoHDLt. In the HDL of Tangier patients it was estimated that, compared with normal individuals, the concentration of apoLp-Gln-I was decreased about 600-fold and the concentration of apoLp-Gln-II about 17-fold. The decrease in these apoproteins was not due to preferential segregation with the lipoprotein fractions of d < 1.063 g/ml or with the plasma proteins of d > 1.21 g/ml. Tangier apoLp-Gln-I and apoLp-Gln-II appeared to be immunochemically identical with their normal counterparts, and no differences between the two sets of apoproteins were detected on polyacrylamide gel electrophoresis at pH 9.4 or 2.9. These results are most compatible with the hypothesis that the hereditary defect in Tangier disease is a mutation in an allele-regulating synthesis of

  2. [Electron microscopic study of wedge-shaped defects of teeth on initial stage].

    PubMed

    Makeeva, I M; Biakova, S F; Chuev, V P; Sheveliuk, Iu V

    2009-01-01

    The aim of thes; study was to observe initial stage of wedge-shaped defects under scanning electron microscopy without prior samples preparation. There were revealed special features of structure of enamel and cement at initial stage of wedge-shaped defects in comparison to normal tissues.

  3. REVIEWS OF TOPICAL PROBLEMS: Defects in liquid crystals: homotopy theory and experimental studies

    NASA Astrophysics Data System (ADS)

    Kurik, Mikhail V.; Lavrentovich, O. D.

    1988-03-01

    The fundamental concepts of the homotopy theory of defects in liquid crystals and the results of experimental studies in this field are presented. The concepts of degeneracy space, homotopy groups, and topological charge, which are used for classifying the topologically stable inhomogeneous distributions in different liquid-crystalline phases are examined (uni and biaxial nematics, cholesterics, smectics, and columnar phases). Experimental data are given for the different mesophases on the structure and properties of dislocations, disclinations, point defects in the volume (hedgehogs) and on the surface of the medium (boojums), monopoles, domain formations, and solitons. Special attention is paid to the results of studies of defects in closed volumes (spherical drops, cylindrical capillaries), and to the connection between the topological charges of these defects and the character of the orientation of the molecules of the liquid crystal at the surface. A set of fundamentally new effects that can occur in studying the topological properties of defects in liquid crystals is discussed.

  4. Agricultural chemical exposures and birth defects in the Eastern Cape Province, South Africa A case – control study

    PubMed Central

    Heeren, Gudrun A; Tyler, Joanne; Mandeya, Andrew

    2003-01-01

    Background South Africa is one of the major users of pesticides on the African continent. The Eastern Cape is the second largest province in South Africa. There has been growing concern about the occurrence of certain birth defects which seemed to have increased in the past few years. In this paper we investigate associations between exposure to agricultural chemicals and certain birth defects. Few such studies have been undertaken in the developing world previously. Methods Between September 2000 and March 2001 a case – control study was conducted among rural women in the area of the Eastern cape to investigate the association between women's exposure to pesticides and the occurrence of birth defects. Information on birth defects was obtained from the register of the Paediatrics Department at the Cecilia Makiwane Hospital in Mdantsane, one of the largest referral hospitals in the province. The cases were children who were diagnosed with selected birth defects. The controls were children born in the same areas as the cases. Exposure information on the mothers was obtained by interview concerning from their activities in gardens and fields. Data were analysed using conditional logistic regression. Results A total of 89 case mothers and 178 control mothers was interviewed. Babies with birth defects were seven times more likely to be born to women exposed to chemicals used in gardens and fields compared to no reported exposure (Odds Ratio 7.18, 95% CI 3.99, 13.25); and were almost twice as likely to be born to women who were involved in dipping livestock used to prevent ticks (OR 1.92, 95% CI 1.15, 3.14). They were also 6.5 times more likely to be born to women who were using plastic containers for fetching water (OR 6.5, 95% CI 2.2, 27.9). Some of these containers had previously contained pesticides (OR 1.87, 95% CI 1.06, 3.31). Conclusions These findings suggest a link between exposure to pesticides and certain birth defects among the children of rural South

  5. Defects in Peroxisomal 6-Phosphogluconate Dehydrogenase Isoform PGD2 Prevent Gametophytic Interaction in Arabidopsis thaliana.

    PubMed

    Hölscher, Christian; Lutterbey, Marie-Christin; Lansing, Hannes; Meyer, Tanja; Fischer, Kerstin; von Schaewen, Antje

    2016-05-01

    We studied the localization of 6-phosphogluconate dehydrogenase (PGD) isoforms of Arabidopsis (Arabidopsis thaliana). Similar polypeptide lengths of PGD1, PGD2, and PGD3 obscured which isoform may represent the cytosolic and/or plastidic enzyme plus whether PGD2 with a peroxisomal targeting motif also might target plastids. Reporter-fusion analyses in protoplasts revealed that, with a free N terminus, PGD1 and PGD3 accumulate in the cytosol and chloroplasts, whereas PGD2 remains in the cytosol. Mutagenesis of a conserved second ATG enhanced the plastidic localization of PGD1 and PGD3 but not PGD2. Amino-terminal deletions of PGD2 fusions with a free C terminus resulted in peroxisomal import after dimerization, and PGD2 could be immunodetected in purified peroxisomes. Repeated selfing of pgd2 transfer (T-)DNA alleles yielded no homozygous mutants, although siliques and seeds of heterozygous plants developed normally. Detailed analyses of the C-terminally truncated PGD2-1 protein showed that peroxisomal import and catalytic activity are abolished. Reciprocal backcrosses of pgd2-1 suggested that missing PGD activity in peroxisomes primarily affects the male gametophyte. Tetrad analyses in the quartet1-2 background revealed that pgd2-1 pollen is vital and in vitro germination normal, but pollen tube growth inside stylar tissues appeared less directed. Mutual gametophytic sterility was overcome by complementation with a genomic construct but not with a version lacking the first ATG. These analyses showed that peroxisomal PGD2 activity is required for guided growth of the male gametophytes and pollen tube-ovule interaction. Our report finally demonstrates an essential role of oxidative pentose-phosphate pathway reactions in peroxisomes, likely needed to sustain critical levels of nitric oxide and/or jasmonic acid, whose biosynthesis both depend on NADPH provision. © 2016 American Society of Plant Biologists. All Rights Reserved.

  6. Tight-binding calculation studies of vacancy and adatom defects in graphene

    DOE PAGES

    Zhang, Wei; Lu, Wen-Cai; Zhang, Hong-Xing; ...

    2016-02-19

    Computational studies of complex defects in graphene usually need to deal with a larger number of atoms than the current first-principles methods can handle. We show a recently developed three-center tight-binding potential for carbon is very efficient for large scale atomistic simulations and can accurately describe the structures and energies of various defects in graphene. Using the three-center tight-binding potential, we have systematically studied the stable structures and formation energies of vacancy and embedded-atom defects of various sizes up to 4 vacancies and 4 embedded atoms in graphene. In conclusion, our calculations reveal low-energy defect structures and provide a moremore » comprehensive understanding of the structures and stability of defects in graphene.« less

  7. Tight-binding calculation studies of vacancy and adatom defects in graphene

    SciTech Connect

    Zhang, Wei; Lu, Wen-Cai; Zhang, Hong-Xing; Ho, K. M.; Wang, C. Z.

    2016-02-19

    Computational studies of complex defects in graphene usually need to deal with a larger number of atoms than the current first-principles methods can handle. We show a recently developed three-center tight-binding potential for carbon is very efficient for large scale atomistic simulations and can accurately describe the structures and energies of various defects in graphene. Using the three-center tight-binding potential, we have systematically studied the stable structures and formation energies of vacancy and embedded-atom defects of various sizes up to 4 vacancies and 4 embedded atoms in graphene. In conclusion, our calculations reveal low-energy defect structures and provide a more comprehensive understanding of the structures and stability of defects in graphene.

  8. Comparative theoretical study of adsorption of lithium polysulfides (Li2Sx) on pristine and defective graphene

    NASA Astrophysics Data System (ADS)

    Jand, Sara Panahian; Chen, Yanxin; Kaghazchi, Payam

    2016-03-01

    Adsorption of Li2Sx on pristine and defective (Stone-Wales (SW) and vacancy) graphene is studied using density functional theory. Results show that the interaction between Li2Sx and graphene is dominated by dispersion interaction (physisorption), which depends on the size of molecule as well as the existence and type of defect sites on graphene. We find that single Li2Sx molecules interact only slightly stronger to the SW sites than to the defect-free sites, but they interact very strongly with single-vacant defects. In the later cases, the vacant site catches one S atom from the Li2Sx molecule, leading to the formation of a Li2Sx-1 molecule, which adsorbs weakly on the created S-doped graphene. This study suggests that defect sites can not improve the ability of graphene to catch lithium polysulfides in Li-S batteries.

  9. Exploring the interaction between lithium ion and defective graphene surface using dispersion corrected DFT studies

    SciTech Connect

    Vijayakumar, M.; Hu, Jian Z.

    2013-10-15

    To analyze the lithium ion interaction with realistic graphene surfaces, we carried out dispersion corrected DFT-D3 studies on graphene with common point defects and chemisorbed oxygen containing functional groups along with defect free graphene surface. Our study reveals that, the interaction between lithium ion (Li+) and graphene is mainly through the delocalized π electron of pure graphene layer. However, the oxygen containing functional groups pose high adsorption energy for lithium ion due to the Li-O ionic bond formation. Similarly, the point defect groups interact with lithium ion through possible carbon dangling bonds and/or cation-π type interactions. Overall these defect sites render a preferential site for lithium ions compared with pure graphene layer. Based on these findings, the role of graphene surface defects in lithium battery performance were discussed.

  10. Etiologic heterogeneity of neural tube defects. II. Clues from family studies.

    PubMed Central

    Khoury, M J; Erickson, J D; James, L M

    1982-01-01

    We previously reported that among neural tube defects (NTDs) with no known causes the ones that occur alone (singles) have different epidemiologic characteristics from those that occur in combination with other defects (multiples), suggesting an underlying causal heterogeneity. In this study, we compared family histories of 223 single NTD cases and 66 multiple cases ascertained through the Metropolitan Atlanta Congenital Defects Program (MACDP) between 1970 and 1979. Compared with siblings of multiples, siblings of singles had a higher precurrence rate for NTDs (2.0% vs. 0.0%) and for birth defects in general (10.9% vs. 3.0%). Furthermore, siblings of singles that were born within 2 years before the birth of the index case had a higher precurrence rate for NTDs (8.0% vs. 1.1%) and for major birth defects (20.0% vs. 2.9%) than had those born earlier. These results further suggest that NTDs are etiologically heterogeneous, depending on the presence of associated defects, and point to important environmental influences in the increased risk for birth defects among siblings of singles. Larger studies are needed to confirm these data and show that single and multiple NTDs have different recurrence rates, not only for NTDs but also for other birth defects. PMID:7180852

  11. A resin-modified glass ionomer cement barrier for treating degree II furcation defects: a pilot study in dogs.

    PubMed

    Miranda, Letícia Algarves; Gomes, Sabrina Carvalho; Soares, Ilson José; Oppermann, Rui Vicente

    2006-02-01

    The aim of this study was to evaluate in an animal model the healing of degree II furcation defects treated with: an experimental barrier of resin-modified glass-ionomer cement (GIC), a polylactic acid barrier (GUI), and flap surgery (CTR). In 3 beagles, 18 class II furcation defects were surgically produced in mandibular and maxillary premolars and exposed to plaque accumulation for 21 days. Following a full flap, notches were made at the base to the bone defect. GIC barriers were prepared immediately before use from a commercial product and fit to place with the same product. The GIC barriers were removed after 30 days and the dogs euthanized after 120 days. Histologic sections were analyzed in a computer-assisted microscope. Epithelium, new cementum with inserting fibers, and connective tissue lining the root surface in-between notches were measured and medians of percentage values calculated. In the GIC, epithelium constituted 3.5% (median values) of the notch-to-notch root area; new cementum was 83.6% and connective tissue 12.9%. These values were 0%, 73.6%, and 26.4% for the GUI group and 35.6%, 43.2%, and 0% for the CTR group. Bone fill median values were 54.3% for GIC, 20.6% for GUI, and 24.6% for CTR. GIC and GUI prevented epithelial migration and promoted the formation of new periodontal tissues in experimentally induced class II furcation defects in dogs.

  12. Mothers of Kids with Severe Birth Defects May Have Shorter Lives: Study

    MedlinePlus

    ... With Severe Birth Defects May Have Shorter Lives: Study But the overall risk of early death is ... women just don't die very frequently," stressed study lead author Dr. Eyal Cohen. He's a physician ...

  13. Interaction between epidemiology and laboratory sciences in the study of birth defects: Design of birth defects risk factor surveillance in metropolitan Atlanta

    SciTech Connect

    Lynberg, M.C.; Khoury, M.J. )

    1993-01-01

    Despite years of research, the etiology of most birth defects remains largely unknown. Interview instruments have been the major tools in the search for environmental causes of birth defects. Because of respondents' problems with recognition and recall, interviews are limited in their capacity to measure certain exposures. Laboratory scientists can have a major impact on defining markers of environmental exposure and genetic susceptibility. The Centers for Disease Control is starting a case-control study of serious birth defects on the basis of a population-based surveillance system for birth defects diagnosed during the first year of life in metropolitan Atlanta, Each year, 300 infants with selected birth defects (case subjects) and 100 population-based control subjects (infants without birth defects) will be enrolled in an ongoing study that will supplement surveillance. In addition to conducting extensive maternal interviews, we will collect blood and urine specimens from case and control subjects and their mothers for laboratory testing. Eventually, some environmental sampling may be incorporated. Particular areas of emphasis are (1) nutritional factors, specifically measuring maternal folic acid levels and other micronutrients (e.g., zinc) to explore their role in the etiology of neural tube defects, (2) substance use, specifically measuring cocaine metabolites in the blood and urine to explore their role for specific vascular disruption defects, and (3) environmental factors such as pesticides and aflatoxins, to explore their potential relationships with specific defects. In addition, a DNA bank will be maintained to evaluate the role of specific candidate genes in the etiology of birth defects. The development and testing of these methods could be useful to assess the interaction between environmental exposures and genetic susceptibility in the etiology of birth defects. 15 refs., 1 fig., 1 tab.

  14. First-principles study of native point defects in hafnia and zirconia

    NASA Astrophysics Data System (ADS)

    Zheng, J. X.; Ceder, G.; Maxisch, T.; Chim, W. K.; Choi, W. K.

    2007-03-01

    A first-principles study of native point defects in hafnia (HfO2) and zirconia (ZrO2) is carried out to identify dominant defects under different oxygen chemical potentials and Fermi levels. Oxygen vacancies and oxygen interstitials in both HfO2 and ZrO2 show negative- U behavior. It is shown that HfO2 is less prone to the formation of oxygen point defects than ZrO2 under the same oxygen chemical potential. When the Fermi level is constrained to be within the band gap of silicon, the dominant defects are negatively charged hafnium or zirconium vacancies under intermediate to high oxygen chemical potential. We find no evidence for magnetic defects.

  15. Oxygen defects in amorphous Al2O3: A hybrid functional study

    NASA Astrophysics Data System (ADS)

    Guo, Zhendong; Ambrosio, Francesco; Pasquarello, Alfredo

    2016-08-01

    The electronic properties of the oxygen vacancy and interstitial in amorphous Al2O3 are studied via ab initio molecular dynamics simulations and hybrid functional calculations. Our results indicate that these defects do not occur in amorphous Al2O3, due to structural rearrangements which assimilate the defect structure and cause a delocalization of the associated defect levels. The imbalance of oxygen leads to a nonstoichiometric compound in which the oxygen occurs in the form of O2- ions. Intrinsic oxygen defects are found to be unable to trap excess electrons. For low Fermi energies, the formation of peroxy linkages is found to be favored leading to the capture of holes. The relative +2/0 defect levels occur at 2.5 eV from the valence band.

  16. Theoretical Studies on the Extrinsic Defects of Montmorillonite in Soft Rock

    NASA Astrophysics Data System (ADS)

    He, Man-Chao; Fang, Zhi-Jie; Zhang, Ping

    Using the first-principles methods, we study the formation energetics and charge doping properties of the extrinsic substitutional defects in montmorillonite. Especially, we choose Be, Mg, Ca, Fe, Cr, Mn, Cu, Zn as extrinsic defects to substitute for Al atoms. By systematically calculating the impurity formation energies and transition energy levels, we find that all Group II defects introduce the relative shallow transition energy levels in montmorillonite. Among them, MgAl has the shallowest transition energy level at 0.10 eV above the valence band maximum. The transition-elemental defects FeAl, CrAl, and MnAl are found to have relatively low formation energies, suggesting their easy formation in montmorillonite under natural surrounding conditions. Our calculations show that the defects CuAl and ZnAl have high formation energies, which exclude the possibility of their formation in montmorillonite.

  17. Study of Residual Stress and Vacancy Defects in Oxide Dispersion Strengthened Steels

    NASA Astrophysics Data System (ADS)

    Slugeň, V.; Veterníková, J.; Kilpeläinen, S.; Tuomisto, F.

    This study was focused on commercial oxide-dispersion strengthened (ODS) steels -MA 956 (20%Cr), ODM 751 (16%Cr) and ODS Eurofer (9%Cr), developed for fuel cladding of GEN IV reactors. The ODS steels are described in order to comparison their microstructure features. Vacancy defects were observed by Doppler Broadening Spectroscopy (DBS) and Positron Annihilation Lifetime Spectroscopy (PALS). Residual stress proportional to all kinds of defects was investigated by Magnetic Barkhausen Noise (MBN) measurement. The positron techniques demonstrated the highest defect concentration for ODS Eurofer followed by MA 956. The lowest defect density belongs to ODM 751; although these defects are the largest (three or four vacancy clusters). MA 956 and ODS Eurofer have di-vacancies in predominance. MBN results are in a good accordance with positron techniques. The highest residual stress is for ODS Eurofer, followed by MA 956. Finally, the lowest residual stress proportional to hardness is found for ODM 751.

  18. Inversion of tone burst eddy current thermography data for defect sizing - A simulation study

    NASA Astrophysics Data System (ADS)

    Biju, N.; Ganesan, N.; Krishnamurthy, C. V.; Balasubramaniam, Krishnan

    2013-01-01

    In this paper, the results of the simulation study to reconstruct the size of the defects from the data obtained using the active thermography technique based on transient induction heating, will be presented. The forward problem of electro-magnetic induction was solved with an axi-symmetric model using finite element method and from the temperature history profiles, an inverse analysis was performed using Genetic Algorithm (GA) to size the defect. Simulations were performed using the finite element model to obtain the temperature data which are then used to reconstruct the radius (rd) and depth (dd) of the wall thinning defects in aluminum plate using inversion method. Two cases, coil inner radius less than the defect radius (rcdefect radius (rc>rd), were considered. The analysis of the sensitivity of coil dimensions to the calculated peak temperature at the observation point was carried out.

  19. Oxygen defects in amorphous Al{sub 2}O{sub 3}: A hybrid functional study

    SciTech Connect

    Guo, Zhendong Ambrosio, Francesco; Pasquarello, Alfredo

    2016-08-08

    The electronic properties of the oxygen vacancy and interstitial in amorphous Al{sub 2}O{sub 3} are studied via ab initio molecular dynamics simulations and hybrid functional calculations. Our results indicate that these defects do not occur in amorphous Al{sub 2}O{sub 3}, due to structural rearrangements which assimilate the defect structure and cause a delocalization of the associated defect levels. The imbalance of oxygen leads to a nonstoichiometric compound in which the oxygen occurs in the form of O{sup 2–} ions. Intrinsic oxygen defects are found to be unable to trap excess electrons. For low Fermi energies, the formation of peroxy linkages is found to be favored leading to the capture of holes. The relative +2/0 defect levels occur at 2.5 eV from the valence band.

  20. A study of defects on EUV mask using blank inspection, patterned mask inspection, and wafer inspection

    SciTech Connect

    Huh, S.; Ren, L.; Chan, D.; Wurm, S.; Goldberg, K. A.; Mochi, I.; Nakajima, T.; Kishimoto, M.; Ahn, B.; Kang, I.; Park, J.-O.; Cho, K.; Han, S.-I.; Laursen, T.

    2010-03-12

    The availability of defect-free masks remains one of the key challenges for inserting extreme ultraviolet lithography (EUVL) into high volume manufacturing. yet link data is available for understanding native defects on real masks. In this paper, a full-field EUV mask is fabricated to investigate the printability of various defects on the mask. The printability of defects and identification of their source from mask fabrication to handling were studied using wafer inspection. The printable blank defect density excluding particles and patterns is 0.63 cm{sup 2}. Mask inspection is shown to have better sensitivity than wafer inspection. The sensitivity of wafer inspection must be improved using through-focus analysis and a different wafer stack.

  1. Defect-tuning exchange bias of ferromagnet/antiferromagnet core/shell nanoparticles by numerical study.

    PubMed

    Mao, Zhongquan; Zhan, Xiaozhi; Chen, Xi

    2012-07-11

    The influence of non-magnetic defects on the exchange bias (EB) of ferromagnet (FM)/antiferromagnet (AFM) core/shell nanoparticles is studied by Monte Carlo simulations. It is found that the EB can be tuned by defects in different positions. Defects at both the AFM and FM interfaces reduce the EB field while they enhance the coercive field by decreasing the effective interface coupling. However, the EB field and the coercive field show respectively a non-monotonic and a monotonic dependence on the defect concentration when the defects are located inside the AFM shell, indicating a similar microscopic mechanism to that proposed in the domain state model. These results suggest a way to optimize the EB effect for applications.

  2. Bone tissue ultrastructural defects in a mouse model for osteogenesis imperfecta: a Raman spectroscopy study

    NASA Astrophysics Data System (ADS)

    Chen, Tsoching; Kozloff, Kenneth M.; Goldstein, Steven A.; Morris, Michael D.

    2004-07-01

    Osteogenesis imperfecta (OI) is genetic defect in which the genes that code for the α1(I) or α2(I) chains of type I collagen are defective. The defects often result in substitution of a bulky amino acid for glycine, causing formation of collagen that can not form the normal triple helix. Depending on the details of the defects, the outcomes range from controllable to lethal. This study focuses on OI type IV, a more common and moderately severe form of the disease. People with the disease have a substantial increase in the risk and rate of fracture. We examine the spectroscopic consequences of these defects, using a mouse model (BRTL) that mimics OI type IV. We compare Raman images from tibial cortical tissue of wild-type mice and BRTL mice with single copy of mutation and show that both mineral to matrix ratios and collagen inter-fibril cross-links are different in wild-type and mutant mice.

  3. Vacancy-type defects induced by grinding of Si wafers studied by monoenergetic positron beams

    SciTech Connect

    Uedono, Akira; Yoshihara, Nakaaki; Mizushima, Yoriko; Kim, Youngsuk; Nakamura, Tomoji; Ohba, Takayuki; Oshima, Nagayasu; Suzuki, Ryoichi

    2014-10-07

    Vacancy-type defects introduced by the grinding of Czochralski-grown Si wafers were studied using monoenergetic positron beams. Measurements of Doppler broadening spectra of the annihilation radiation and the lifetime spectra of positrons showed that vacancy-type defects were introduced in the surface region (<98 nm), and the major defect species were identified as (i) relatively small vacancies incorporated in dislocations and (ii) large vacancy clusters. Annealing experiments showed that the defect concentration decreased with increasing annealing temperature in the range between 100 and 500°C. After 600–700°C annealing, the defect-rich region expanded up to about 170 nm, which was attributed to rearrangements of dislocation networks, and a resultant emission of point defects toward the inside of the sample. Above 800°C, the stability limit of those vacancies was reached and they started to disappear. After the vacancies were annealed out (900°C), oxygen-related defects were the major point defects and they were located at <25 nm.

  4. Li NMR study of heavy-fermion LiV2O4 containing magnetic defects

    SciTech Connect

    Zong, X.; Das, S.; Borsa, F.; Vannette, M.; Prozorov, R.; Schmalian, J.; Johnston, D.

    2008-04-21

    We present a systematic study of the variations of the {sup 7}Li NMR properties versus magnetic defect concentration up to 0.83 mol% within the spinel structure of polycrystalline powder samples and a collection of small single crystals of LiV2O4 in the temperature range from 0.5 to 4.2 K. We also report static magnetization measurements and ac magnetic susceptibility measurements at 14 MHz on the samples at low temperatures. Both the NMR spectrum and nuclear spin-lattice relaxation rate are inhomogeneous in the presence of the magnetic defects. The NMR data for the powders are well explained by assuming that (i) there is a random distribution of magnetic point defects, (ii) the same heavy Fermi liquid is present in the samples containing the magnetic defects as in magnetically pure LiV2O4, and (iii) the influences of the magnetic defects and of the Fermi liquid on the magnetization and NMR properties are separable. In the single crystals, somewhat different behaviors are observed. Remarkably, the magnetic defects in the powder samples show evidence of spin freezing below T {approx} 1.0 K, whereas in the single crystals with similar magnetic defect concentration no spin freezing was found down to 0.5 K. Thus different types of magnetic defects and/or interactions between them appear to arise in the powders versus the crystals, possibly due to the substantially different synthesis conditions of the powders and crystals.

  5. Structure and energy of point defects in TiC: An ab initio study

    NASA Astrophysics Data System (ADS)

    Sun, Weiwei; Ehteshami, Hossein; Korzhavyi, Pavel A.

    2015-04-01

    We employ first-principles calculations to study the atomic and electronic structure of various point defects such as vacancies, interstitials, and antisites in the stoichiometric as well as slightly off-stoichiometric Ti1 -cCc (including both C-poor and C-rich compositions, 0.49 ≤c ≤0.51 ). The atomic structure analysis has revealed that both interstitial and antisite defects can exist in split conformations involving dumbbells. To characterize the electronic structure changes caused by a defect, we introduce differential density of states (dDOS) defined as a local perturbation of the density of states (DOS) on the defect site and its surrounding relative to the perfect TiC. This definition allows us to identify the DOS peaks characteristic of the studied defects in several conformations. So far, characteristic defect states have been discussed only in connection with carbon vacancies. Here, in particular, we have identified dDOS peaks of carbon interstitials and dumbbells, which can be used for experimental detection of such defects in TiC. The formation energies of point defects in TiC are derived in the framework of a grand-canonical formalism. Among the considered defects, carbon vacancies and interstitials are shown to have, respectively, the lowest and the second-lowest formation energies. Their formation energetics are consistent with the thermodynamic data on the phase stability of nonstoichiometric TiC. A cluster type of point defect is found to be next in energy, a titanium [100] dumbbell terminated by two carbon vacancies.

  6. Dental enamel defects in Italian children with cystic fibrosis: an observational study.

    PubMed

    Ferrazzano, G F; Sangianantoni, G; Cantile, T; Amato, I; Orlando, S; Ingenito, A

    2012-03-01

    The relationship between cystic fibrosis (CF) and caries experience has already been explored, but relatively little information is available on dental enamel defects prevalence among children affected by cystic fibrosis. The aim of this study was to investigate this issue in deciduous and permanent teeth of children with CF resident in southern Italy. This cross sectional observational study was undertaken between October 2009 and March 2010. 88 CF patients and 101 healthy age-matched participated in this study. The prevalence of dental enamel defects was calculated using a modified Developmental Defects of Enamel (DDE) index. The comparison of dental enamel defects prevalence among groups was carried out using regression binary logistic analysis. In the CF subjects there was a higher prevalence (56%) of enamel defects in comparison to the healthy group (22%). The most prevalent enamel defect was hypoplasia with loss of enamel (23% of CF patients vs 1 1/2% of control group) in permanent teeth. This study confirms that children with cystic fibrosis are at increased risk of developing hypoplastic defects on their permanent teeth.

  7. Radiation defect dynamics in Si at room temperature studied by pulsed ion beams

    SciTech Connect

    Wallace, J. B.; Myers, M. T.; Charnvanichborikarn, S.; Bayu Aji, L. B.; Kucheyev, S. O.; Shao, L.

    2015-10-07

    The evolution of radiation defects after the thermalization of collision cascades often plays the dominant role in the formation of stable radiation disorder in crystalline solids of interest to electronics and nuclear materials applications. Here, we explore a pulsed-ion-beam method to study defect interaction dynamics in Si crystals bombarded at room temperature with 500 keV Ne, Ar, Kr, and Xe ions. The effective time constant of defect interaction is measured directly by studying the dependence of lattice disorder, monitored by ion channeling, on the passive part of the beam duty cycle. The effective defect diffusion length is revealed by the dependence of damage on the active part of the beam duty cycle. Results show that the defect relaxation behavior obeys a second order kinetic process for all the cases studied, with a time constant in the range of ∼4–13 ms and a diffusion length of ∼15–50 nm. Both radiation dynamics parameters (the time constant and diffusion length) are essentially independent of the maximum instantaneous dose rate, total ion dose, and dopant concentration within the ranges studied. However, both the time constant and diffusion length increase with increasing ion mass. This demonstrates that the density of collision cascades influences not only defect production and annealing efficiencies but also the defect interaction dynamics.

  8. KEEPS: The Kronos Early Estrogen Prevention Study.

    PubMed

    Harman, S M; Brinton, E A; Cedars, M; Lobo, R; Manson, J E; Merriam, G R; Miller, V M; Naftolin, F; Santoro, N

    2005-03-01

    Observational studies have indicated that hormone therapy given at or after menopause is linked to substantial reduction in cardiovascular disease and its risk factors. Recent findings from the Women's Health Initiative (WHI) clinical trial, however, indicate that combined estrogen plus progestin hormone therapy, as well as estrogen-alone hormone therapy (given to women without a uterus), is ineffective in preventing the new onset of cardiac events in previously healthy late menopausal women. Further, the secondary prevention trial, the Heart and Estrogen/progestin Replacement Study (HERS), also failed to demonstrate any benefit of initiation of hormone therapy in women with established coronary heart disease. In light of these results, a hypothesis has arisen that early initiation of hormone therapy, in women who are at the inception of their menopause, will delay the onset of subclinical cardiovascular disease in women. The rationale that earlier intervention than that performed in the WHI and HERS trials will provide cardiovascular benefit to women is the driving force behind the Kronos Early Estrogen Prevention Study, or KEEPS. KEEPS is a multicenter, 5-year clinical trial that will evaluate the effectiveness of 0.45 mg of conjugated equine estrogens, 50 microg weekly transdermal estradiol (both in combination with cyclic oral, micronized progesterone, 200 mg for 12 days each month), and placebo in preventing progression of carotid intimal medial thickness and the accrual of coronary calcium in women aged 42-58 years who are within 36 months of their final menstrual period. A total of 720 women are planned to be enrolled in 2005, with an anticipated close-out of the trial in 2010. This overview summarizes the recruitment and methodology of the KEEPS trial.

  9. Paramagnetic resonance studies of defects in titanium dioxide crystals

    NASA Astrophysics Data System (ADS)

    Yang, Shan

    Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify and characterize point defects in TiO2 crystals having the rutile structure. Defect production occurs at low temperature during illumination with 442 nm laser light. Spectra with S = 1/2 and S = 1 are assigned to singly ionized and neutral oxygen vacancies, respectively. These oxygen vacancies have their unpaired spins localized on the two neighboring titanium ions aligned along the [001] axis. A Ti3+ ion next to a substitutional Si4+ ion, a Ti3+ self-trapped electron, and a self-trapped hole on the oxygen sublattice are also observed. Fluorine ions substitute for oxygen and are present as unintentional impurities in TiO2 crystals. Isolated singly ionized fluorine donors in an as-grown (fully oxidized) crystal convert to their neutral charge state during exposure to 442 nm laser light at 6 K. These donors return to the singly ionized charge state within a few seconds when the light is removed. In contrast, the neutral fluorine donors are observed at 6 K without photoexcitation after a crystal is reduced at 600 ºC in flowing nitrogen gas. The angular dependences of the EPR and ENDOR spectra provide a complete set of spin-Hamiltonian parameters (principal values are 1.9746, 1.9782, and 1.9430 for the g matrix and -0.23, 0.47, and 5.15 MHz for the 19F hyperfine matrix). These matrices suggest that the unpaired electron is localized primarily on one of the two equivalent neighboring substitutional titanium ions, i.e., the ground state of the neutral fluorine donor in rutile-structured TiO2 is a Ti 3+ ion adjacent to a F- ion. Hydrogen, in the form of an OH- ion, is a shallow donor in TiO2. In the neutral charge state, the unpaired electron forms an adjacent Ti3+ ion. The hydrogen EPR signal cannot be produced in oxidized crystals containing fluorine donors, which suggest that hydrogen is a shallower donor than fluorine in TiO2 (rutile) crystals. The hydrogen EPR

  10. Exploiting Defect Clustering to Screen Bare Die for Infant Mortality Failure: An Experimental Study

    NASA Technical Reports Server (NTRS)

    Lakin, David R., II; Singh, Adit D.

    1999-01-01

    We present the first experimental results to establish that a binning strategy based on defect clustering can be used to screen bare die for early life failures. The data for this study comes from the SEMATECH test methods experiment.

  11. Exploiting Defect Clustering to Screen Bare Die for Infant Mortality Failure: An Experimental Study

    NASA Technical Reports Server (NTRS)

    Lakin, David R., II; Singh, Adit D.

    1999-01-01

    We present the first experimental results to establish that a binning strategy based on defect clustering can be used to screen bare die for early life failures. The data for this study comes from the SEMATECH test methods experiment.

  12. Long-term effect on tooth vitality of regenerative therapy in deep periodontal bony defects: a retrospective study.

    PubMed

    de Sanctis, Massimo; Goracci, Cecilia; Zucchelli, Giovanni

    2013-01-01

    Over the last few decades, many authors have investigated the effect of periodontal disease and treatment on pulpal status with controversial results. This study was conducted to verify whether periodontal disease in a deep intrabony defect and complex therapy, including aggressive root planing such as in periodontal regeneration, have an influence on tooth vitality. One hundred thirty-seven patients who fulfilled the requirements were included. The collected data did not support the need for "preventive" root canal treatment in severely compromised teeth that are planned to undergo periodontal regenerative surgery.

  13. Study on dynamic compression performance of K9 glass with prefabricated defects

    NASA Astrophysics Data System (ADS)

    Hu, Changming; Wang, Xiang; Cai, Lingcang; Liu, Cangli

    2012-03-01

    We conducted several planar impact experiments to study dynamic compression properties of K9 glass on powder gun using Photon Doppler Velocimetry (PDV) measure system. Samples are prefabricated some internal meso-defects by laser three-dimensional erosion technique before shock loading. Free surface velocities recorded by high temporal-spatial resolution PDV array or multi-point PDV. All these experimental results show some different properties influenced by evolutions of pre-existed internal defects face on free surface velocity profiles. The critical compression strength and dynamic evolution information of pre-existed internal defects can be derived from the experimental results tentatively.

  14. Theoretical study of boron nitride nanotubes with defects in nitrogen-rich synthesis.

    PubMed

    Kang, Hong Seok

    2006-03-16

    On the basis of calculations using the density functional theory, it is shown that BNNT synthesis could produce tubes deprived of one (B1 hole) or two (B2 hole) boron atoms under the condition where nitrogen atoms exist in excess throughout this study. The relative populations of various isomers of defective tubes will depend on the chirality of the tube. Interestingly, calculations show that B2 holes are much more favored than B1 holes, particularly in armchair tubes. Electronic properties are modified in such a way that the band gap is decreased through the introduction of defect states inside the gap. Magnetic properties will also be dependent on the chirality. The majority of armchair tubes with B2 holes will be nonmagnetic, while the majority of zigzag tubes with defects will exhibit magnetism. Contrary to the case of defect-free BNNT, the defective tubes are expected to be easily subject to reduction by accommodating excess electrons in the presence of Li atoms. In addition, the defect sites will show a higher affinity toward hydrogenation than the defect-free sites.

  15. First-principles study of point defects in CePO4 monazite

    NASA Astrophysics Data System (ADS)

    Yi, Yong; Zhao, Xiaofeng; Teng, Yuancheng; Bi, Beng; Wang, Lili; Wu, Lang; Zhang, Kuibao

    2016-12-01

    CePO4 monazite is an important radiation-resistant material that may act as a potential minor actinides waste form. Here, we present the results of the calculations for the basic radiation defect modellings in CePO4 crystals, along with the examination of their defect formation energies and effect of the defect concentrations. This study focused on building a fully-relaxed CePO4 model with the step iterative optimization from the DFT-GGA calculations using the VASP and CASTEP databases. The results show that the Frenkel defect configuration resulting from the center interstitials has a lower energy when compared to two adjacent orthophosphate centers (the saddle point position). High formation energies were found for all the types of intrinsic Frenkel and vacancy defects. The formation energies conform to the following trend (given in the decreasing order of energy): Ce Frenkel (12.41 eV) > O Frenkel (11.02 eV) > Ce vacancy (9.09 eV) > O vacancy (6.69 eV). We observed almost no effect from the defect concentrations on the defect formation energies.

  16. Anisotropic compressive response of Stone-Thrower-Wales defects in graphene: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Rajasekaran, G.; Parashar, Avinash

    2016-09-01

    The mechanical properties of graphene sheet can be tailored with the help of topological defects. In this research article, the effects of Stone-Thrower-Wales (STW) defects on the mechanical properties of graphene sheet was investigated with the help of molecular dynamics based simulations. Authors has made an attempt to analyse the stress field developed in and around the vicinity of defect due to bond reorientation and further systematic evaluation has been carried out to study the effect of these stress fields against the applied axial compressive load. The results obtained with the pristine graphene were made to compare with the available open literature and the results were reported to be in good agreement with theoretical and experimental data. It was predicted that graphene with STW defect cannot able to bear compressive strength in zigzag direction, whereas on the other hand it was predicted that graphene sheet containing STW defect can bear higher compressive load in armchair direction, which shows an anisotropic response of STW defects in graphene. From the obtained results it can be observed that orientation of STW defects and the loading direction plays an important role to alter the strength of graphene under axial compression.

  17. Native defects in GaN: a hybrid functional study

    NASA Astrophysics Data System (ADS)

    Diallo, Ibrahima Castillo; Demchenko, Denis

    Intrinsic defects play an important role in the performance of GaN-based devices. We present hybrid density functional calculations of the electronic and possible optical properties of interstitial N (Ni-Ni) , N antisite (NGa) , interstitial Ga (Gai) , Ga antisite (GaN) , Ga vacancy (VGa) , N vacancy (VN) and Ga-N divacancies (VGaVN) in GaN. Our results show that the vacancies display relatively low formation energies in certain samples, whereas antisites and interstitials are energetically less favorable. However, interstitials can be created by electron irradiation. For instance, in 2.5 MeV electron-irradiated GaN samples, a strong correlation between the frequently observed photoluminescence (PL) band centered around 0.85 eV accompanied with a rich phonon sideband of ~0.88 eV and the theoretical optical behavior of interstitial Ga is discussed. N vacancies are found to likely contribute to the experimentally obtained green luminescence band (GL2) peaking at 2.24 eV in high-resistivity undoped and Mg-doped GaN. National Science Foundation (DMR-1410125) and the Thomas F. and Kate Miller Jeffress Memorial Trust.

  18. High resolution Laplace DLTS studies of defects in ion-implanted silicon

    NASA Astrophysics Data System (ADS)

    Evans-Freeman, J. H.; Abdelgader, N.; Kan, P. Y. Y.; Peaker, A. R.

    2002-01-01

    We have used high resolution Laplace deep level transient spectroscopy (LDLTS) to investigate defects in n-type silicon caused by implantation of Si, Ge or Er with doses of the order of 1×10 9 cm-2. These are compared with defects created in proton irradiated n-type silicon. Unlike the simple proton irradiated case, LDLTS spectra of ion implanted silicon show that there are many emission rates associated with defects with energies in the region of Ec-400 meV. We have carried out annealing studies and Laplace DLTS depth profiling and show that the complex spectra measured from a region less than half way through the implant simplify as the profile is moved through the implant and towards the tail. Annealing studies show that these defects survive an anneal that should remove the E-centre.

  19. Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region.

    PubMed

    Wang, Haochen; De Steur, Hans; Chen, Gong; Zhang, Xiaotian; Pei, Lijun; Gellynck, Xavier; Zheng, Xiaoying

    2016-03-09

    Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs) through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages) and a control group received ordinary flour (three villages). NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs) method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207-0473, p < 0.001). In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory) folic acid fortification in China.

  20. Effectiveness of Folic Acid Fortified Flour for Prevention of Neural Tube Defects in a High Risk Region

    PubMed Central

    Wang, Haochen; De Steur, Hans; Chen, Gong; Zhang, Xiaotian; Pei, Lijun; Gellynck, Xavier; Zheng, Xiaoying

    2016-01-01

    Despite efforts to tackle folate deficiency and Neural Tube Defects (NTDs) through folic acid fortification, its implementation is still lacking where it is needed most, highlighting the need for studies that evaluate the effectiveness of folic acid fortified wheat flour in a poor, rural, high-risk, NTD region of China. One of the most affected regions, Shanxi Province, was selected as a case study. A community intervention was carried out in which 16,648 women of child-bearing age received fortified flour (eight villages) and a control group received ordinary flour (three villages). NTD birth prevalence and biological indicators were measured two years after program initiation at endline only. The effect on the NTD burden was calculated using the disability-adjusted life years (DALYs) method. In the intervention group, serum folate level was higher than in the control group. NTDs in the intervention group were 68.2% lower than in the control group (OR = 0.313, 95% CI = 0.207–0473, p < 0.001). In terms of DALYs, burden in intervention group was approximately 58.5% lower than in the control group. Flour fortification was associated with lower birth prevalence and burden of NTDs in economically developing regions with a high risk of NTDs. The positive findings confirm the potential of fortification when selecting an appropriate food vehicle and target region. As such, this study provides support for decision makers aiming for the implementation of (mandatory) folic acid fortification in China. PMID:27005659

  1. First-principles study of He point-defects in HCP rare-earth metals

    SciTech Connect

    Li, Yang; Chen, Ru; Peng, SM; Long, XG; Wu, Z.; Gao, Fei; Zu, Xiaotao

    2011-05-01

    He defect properties in Sc, Y, Gd, Tb, Dy, Ho, Er and Lu were studied using first-principles calculations based on density functional theory. The results indicate that the formation energy of an interstitial He atom is smaller than that of a substitutional He atom in all hcp rare-earth metals considered. Furthermore, the tetrahedral interstitial position is more favorable than an octahedral position for He defects. The results are compared with those from bcc and fcc metals.

  2. High Serum Estradiol and Heavy Metals Responsible for Human Spermiation Defect-A Pilot Study

    PubMed Central

    Jain, Manish; Kalsi, Amanpreet Kaur; Srivastava, Amita; Gupta, Yogendra Kumar

    2016-01-01

    Introduction Spermiation is a process of releasing sperm into the lumen of seminiferous tubules. Failure in releasing sperm into the lumen is designated as spermiation defect. Spermiation defect cases present as oligo-azoospermia or azoospermia despite normal gonadotropins and testicular histology/cytology. Human spermiation defect never got attention to investigate infertility practice. Most of the information on spermiation defect, so far is from animal experiments. We assume some cases of non-obstructive azoospermia with normal gonadotropins and testicular histology/cytology could be due to spermiation defect. Aim The aim of the study was to find out the underlying aetiology in cases of human spermiation defect. Materials and Methods A total of 13 cases of spermiation defect and 20 fertile men as control constituted study material. Cases were studied for chromosomal abnormalities by conventional karyotyping, sex chromosome mosaicism by interphase XY FISH, Yq microdeletion by STS PCR, sertoli cell quality (function) and quantity (numbers) by serum Anti-Mullerian Hormone (AMH) and inhibin B besides other hormones like Follicular Stimulating Hormone (FSH), prolactin, testosterone and estradiol. Vitamin A concentration in serum was also measured. Presence of heavy metal was investigated by elemental electron microscopy in seminal cells (eight cases) & by spectrometry in serum as well as seminal plasma. Results Chromosomal and Yq microdeletion study failed to detect any abnormalities. AMH, inhibin B and vitamin A were also normal. Estradiol level was high in 6 out of 13 cases (46%) while platinum in seminal cells was high in 4 cases (50%). High (four times or more) serum level of lead and nickel was observed in 11 (85%) and 6 (46%) cases, respectively. Conclusion High serum concentration of heavy metals like lead & nickel or high platinum accumulation in seminal cells or high serum estradiol alone or in combinations may be underlying aetiologic factors in human

  3. Antisite defects at oxide interfaces

    NASA Astrophysics Data System (ADS)

    Chen, Hanghui; Millis, Andrew

    We use ab initio calculations to estimate formation energies of cation (transition metal) antisite defects at oxide interfaces and to understand the basic physical effects that drive or suppress the formation of these defects. We find that antisite defects are favored in systems with substantial charge transfer across the interface, while Jahn-Teller distortions and itinerant ferromagnetism can prevent antisite defects and help stabilize atomically sharp interfaces. Our results enable identification of classes of systems that are more and less susceptible to the formation of antisite defects and motivate a range of experimental studies and further theoretical calculations to further explicate the oxide interface systems. This research was supported by National Science Foundation under Grant No. DMR-1120296 (H. Chen) and DOE-ER-046169 (A. J. Millis).

  4. Pollution Abatement and Prevention Analysis (PAPA) Study.

    DTIC Science & Technology

    1994-07-01

    or reduced at the source first, or whenever feasible; if prevention or reduction was not achievable, then pollution should be recycled; when not...Restoration Account (DERA). (3) The prevention pillar focuses on preventing or eliminating pollution . Source reduction is preferred, but other options such...hazardous materials at Army installations is the main goal of this pillar. The pollution prevention pillar and its emphasis on source reduction/elimination

  5. Ab initio studies of the electronic structure of defects in PbTe

    NASA Astrophysics Data System (ADS)

    Ahmad, Salameh; Mahanti, S. D.; Hoang, Khang; Kanatzidis, M. G.

    2006-10-01

    Understanding the detailed electronic structure of deep defect states in narrow band-gap semiconductors has been a challenging problem. Recently, self-consistent ab initio calculations within density functional theory using supercell models have been successful in tackling this problem. In this paper, we carry out such calculations in PbTe, a well-known narrow band-gap semiconductor, for a large class of defects: cationic and anionic substitutional impurities of different valence, and cationic and anionic vacancies. For the cationic defects, we study the chemical trends in the position of defect levels by looking at series of compounds RPb2n-1Te2n , where R is vacancy or monovalent, divalent, or trivalent atom. Similarly, for anionic defects, we study compounds MPb2nTe2n-1 , where M is vacancy, S, Se or I. We find that the density of states near the top of the valence band and the bottom of the conduction band get significantly modified for most of these defects. This suggests that the transport properties of PbTe in the presence of impurities may not always be interpreted by simple carrier doping (from bound impurity states in the gap) concepts, confirming such ideas developed from qualitative and semiquantitative arguments.

  6. Study of mitochondrial respiratory defects on reprogramming to human induced pluripotent stem cells

    PubMed Central

    Hung, Sandy S.C.; Van Bergen, Nicole J.; Jackson, Stacey; Liang, Helena; Mackey, David A.; Hernández, Damián; Lim, Shiang Y.; Hewitt, Alex W.; Trounce, Ian; Pébay, Alice; Wong, Raymond C.B.

    2016-01-01

    Reprogramming of somatic cells into a pluripotent state is known to be accompanied by extensive restructuring of mitochondria and switch in metabolic requirements. Here we utilized Leber's hereditary optic neuropathy (LHON) as a mitochondrial disease model to study the effects of homoplasmic mtDNA mutations and subsequent oxidative phosphorylation (OXPHOS) defects in reprogramming. We obtained fibroblasts from a total of 6 LHON patients and control subjects, and showed a significant defect in complex I respiration in LHON fibroblasts by high-resolution respiratory analysis. Using episomal vector reprogramming, our results indicated that human induced pluripotent stem cell (hiPSC) generation is feasible in LHON fibroblasts. In particular, LHON-specific OXPHOS defects in fibroblasts only caused a mild reduction and did not significantly affect reprogramming efficiency, suggesting that hiPSC reprogramming can tolerate a certain degree of OXPHOS defects. Our results highlighted the induction of genes involved in mitochondrial biogenesis (TFAM, NRF1), mitochondrial fusion (MFN1, MFN2) and glycine production (GCAT) during reprogramming. However, LHON-associated OXPHOS defects did not alter the kinetics or expression levels of these genes during reprogramming. Together, our study provides new insights into the effects of mtDNA mutation and OXPHOS defects in reprogramming and genes associated with various aspects of mitochondrial biology. PMID:27127184

  7. A histological study of fetoscopic membrane defects to document membrane healing.

    PubMed

    Gratacós, E; Sanin-Blair, J; Lewi, L; Toran, N; Verbist, G; Cabero, L; Deprest, J

    2006-01-01

    To evaluate the rate of spontaneous healing in human fetal membranes after fetoscopy. Membranes from patients that had undergone fetoscopic interventions and delivered in one of the two treatment centers were included in the study. The membranes were examined macroscopically for any remaining defects and if present, the size of the defect in chorion and amnion was measured. Subsequently, the defect was excised and stained with HE for histological evaluation. Additional immunohistochemical staining was performed with Ki-67, cytokeratin and vimentin. The proliferation index (percentage of proliferating cells) was calculated in amnion and chorion. Nineteen membrane defects were included in the study. The median time interval between invasive procedures and delivery was 60 days (range 3-112). All fetoscopic defects (n=19) could be identified in the gestational sac and in none spontaneous closure had occurred. Proliferation indices as measured by inmunohistochemistry were very low (median 2.8%, range 0-7%) in the chorion and 0% in the amnion. No evidence of spontaneous membrane healing was found after fetoscopic procedures, suggesting that the membrane defect normally persists until delivery. Absence of amniotic fluid leakage after invasive procedures may be based on mechanisms other than histologic membrane repair.

  8. A study of photovoltaic loss-mechanisms due to defects and grain boundaries in polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Sopori, B. L.

    1980-01-01

    Various photovoltaic loss mechanisms associated with defects and grain boundaries (gbs) in polycrystalline silicon have been experimentally studied. Analysis was carried out on two types of substrates/cells viz. Wacker Silso and laser-crystallized RTR ribbons. Solar cells were fabricated on selected regions of the substrates and their characteristics related to the substrate structure. Mechanisms related to photovoltaic losses are divided into two categories: electronic and physical. Parameters describing electronic loss mechanisms, such as changes in minority carrier diffusion length, dark current and local photo-current losses were measured, and their dependence on density and type of defects was determined. A variety of analytical techniques were used for this study. These include I-V characterization of solar cells, I-V characterization of gbs, and light intensity dependences of some material parameters. Loss mechanisms associated with physical effects are defect-defect and impurity-defect interactions. It is shown that physical effects such as impurity segregation and defect annihilation can lead to significant loss/gain in photovoltaic characteristics.

  9. Dental enamel defects, caries experience and oral health-related quality of life: a cohort study.

    PubMed

    Arrow, P

    2017-06-01

    The impact of enamel defects of the first permanent molars on caries experience and child oral health-related quality of life was evaluated in a cohort study. Children who participated in a study of enamel defects of the first permanent molars 8 years earlier were invited for a follow-up assessment. Consenting children completed the Child Perception Questionnaire and the faces Modified Child Dental Anxiety Scale, and were examined by two calibrated examiners. ANOVA, Kruskal-Wallis, negative binomial and logistic regression were used for data analyses. One hundred and eleven children returned a completed questionnaire and 91 were clinically examined. Negative binomial regression found that oral health impacts were associated with gender (boys, risk ratio (RR) = 0.73, P = 0.03) and decayed, missing or filled permanent teeth (DMFT) (RR = 1.1, P = 0.04). The mean DMFT of children were sound (0.9, standard deviation (SD) = 1.4), diffuse defects (0.8, SD = 1.7), demarcated defects (1.5, SD = 1.4) and pit defects (1.3, SD = 2.3) (Kruskal-Wallis, P = 0.05). Logistic regression of first permanent molar caries found higher odds of caries experience with baseline primary tooth caries experience (odds ratio (OR) = 1.5, P = 0.01), the number of teeth affected by enamel defects (OR = 1.9, P = 0.05) and lower odds with the presence of diffuse enamel defects (OR = 0.1, P = 0.04). The presence of diffuse enamel defects was associated with lower odds of caries experience. © 2016 Australian Dental Association.

  10. Maternal use of oral contraceptives and risk of birth defects in Denmark: prospective, nationwide cohort study.

    PubMed

    Charlton, Brittany M; Mølgaard-Nielsen, Ditte; Svanström, Henrik; Wohlfahrt, Jan; Pasternak, Björn; Melbye, Mads

    2016-01-06

    Is oral contraceptive use around the time of pregnancy onset associated with an increased risk of major birth defects? In a prospective observational cohort study, data on oral contraceptive use and major birth defects were collected among 880,694 live births from Danish registries between 1997 and 2011. We conservatively assumed that oral contraceptive exposure lasted up to the most recently filled prescription. The main outcome measure was the number of major birth defects throughout one year follow-up (defined according to the European Surveillance of Congenital Anomalies classification). Logistic regression estimated prevalence odds ratios of any major birth defect as well as categories of birth defect subgroups. Prevalence of major birth defects (per 1000 births) was consistent across each oral contraceptive exposure group (25.1, never users; 25.0, use >3 months before pregnancy onset (reference group); 24.9, use 0-3 months before pregnancy onset (that is, recent use); 24.8, use after pregnancy onset). No increase in prevalence of major birth defects was seen with oral contraceptive exposure among women with recent use before pregnancy (prevalence odds ratio 0.98 (95% confidence interval 0.93 to 1.03)) or use after pregnancy onset (0.95 (0.84 to 1.08)), compared with the reference group. There was also no increase in prevalence of any birth defect subgroup (for example, limb defects). It is unknown whether women took oral contraceptives up to the date of their most recently filled prescription. Also, the rarity of birth defects made disaggregation of the results difficult. Residual confounding was possible, and the analysis lacked information on folate, one of the proposed mechanisms. Oral contraceptive exposure just before or during pregnancy does not appear to be associated with an increased risk of major birth defects. BMC was funded by the Harvard T H Chan School of Public Health's Maternal Health Task Force and Department of Epidemiology Rose Traveling

  11. Acquired Color Vision Defects and Hexane Exposure: A Study of San Francisco Bay Area Automotive Mechanics

    PubMed Central

    Beckman, Stella; Eisen, Ellen A.; Bates, Michael N.; Liu, Sa; Haegerstrom-Portnoy, Gunilla; Hammond, S. Katharine

    2016-01-01

    Occupational exposure to solvents, including n-hexane, has been associated with acquired color vision defects. Blue-yellow defects are most common and may be due to neurotoxicity or retinal damage. Acetone may potentiate the neurotoxicity of n-hexane. We present results on nonhexane solvent and hexane exposure and color vision from a cross-sectional study of 835 automotive repair workers in the San Francisco Bay Area, California (2007–2013). Cumulative exposure was estimated from self-reported work history, and color vision was assessed using the Lanthony desaturated D-15 panel test. Log-binomial regression was used to estimate prevalence ratios for color vision defects. Acquired color vision defects were present in 29% of participants, of which 70% were blue-yellow. Elevated prevalence ratios were found for nonhexane solvent exposure, with a maximum of 1.31 (95% confidence interval (CI): 0.86, 2.00) for blue-yellow. Among participants aged ≤50 years, the prevalence ratio for blue-yellow defects was 2.17 (95% CI: 1.03, 4.56) in the highest quartile of nonhexane solvent exposure and 1.62 (95% CI: 0.97, 2.72) in the highest category of exposure to hexane with acetone coexposure. Cumulative exposures to hexane and nonhexane solvents in the highest exposure categories were associated with elevated prevalence ratios for color vision defects in younger participants. PMID:27188942

  12. Intrinsic defect in BiNbO{sub 4}: A density functional theory study

    SciTech Connect

    Lai Kangrong; Zhu Yingtao; Dai Ying; Huang Baibiao

    2012-08-15

    Formation energies, transition energy levels, and electronic properties of various intrinsic defects in BiNbO{sub 4} systems are studied based on the first-principles density-functional theory. Our results indicate that the acceptor defects form easier than donor defects under O rich condition, while it is opposite under Bi rich condition. Under O-rich condition, Bi vacancies (Bi{sub vac}) leading to p-type conductivity are the dominant intrinsic defects, whereas O vacancies (O{sub vac}) inducing moderate n-type conductivity are the dominant intrinsic defects under Bi-rich condition. Among these intrinsic defects, O{sub vac} is a deep donor; to the contrary, Bi{sub vac} is found to be a shallow acceptor which is benefit to the separation and migration of the photogenerated carriers. Consequently, the BiNbO{sub 4} with Bi{sub vac} under O-rich growth condition should be of better photocatalytic performance.

  13. Doubling the number of women consuming vitamin supplement pills containing folic acid: an urgently needed birth defect prevention complement to the folic acid fortification of cereal grains.

    PubMed

    Oakley, G P

    1997-01-01

    The major known environmental causes of birth defects are ancient agents that have been in the environment for centuries but have been only recently discovered-rubella, alcohol, and folic acid deficiency. In the United States, we have made great progress in preventing congenital rubella syndrome. We also have a great opportunity to prevent spina bifida and anencephaly (SBA) by increasing the number of women who daily consume vitamin supplements containing folic acid. Even with the recently announced grain fortification regulations, there are 45 million women unprotected from an SBA-affected pregnancy. This article suggests that a substantial educational campaign could, over a 5-year period, double the number of women consuming folic acid supplement pills and make a substantial contribution toward preventing SBA.

  14. DJ-1-binding compounds prevent oxidative stress-induced cell death and movement defect in Parkinson's disease model rats.

    PubMed

    Miyazaki, Shin; Yanagida, Takashi; Nunome, Kana; Ishikawa, Shizuma; Inden, Masatoshi; Kitamura, Yoshihisa; Nakagawa, Shinsuke; Taira, Takahiro; Hirota, Kosaku; Niwa, Masami; Iguchi-Ariga, Sanae M M; Ariga, Hiroyoshi

    2008-06-01

    Parkinson's disease (PD) is caused by neuronal cell death. Although a precursor of dopamine and inhibitors of dopamine degradation have been used for PD therapy, cell death progresses during treatment. DJ-1, a causative gene product of a familial form of PD, PARK7, plays roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to result in the onset of PD. Superfluous oxidation of cysteine at amino acid 106 (C106) of DJ-1 renders DJ-1 inactive, and such oxidized DJ-1 has been observed in patients with the sporadic form of PD. In this study, we isolated compounds that bind to the region at C106 by a virtual screening. These compounds prevented oxidative stress-induced death of SH-SY5Y cells, embryonic stem cell-derived dopaminergic cells and primary neuronal cells of the ventral mesencephalon, but not that of DJ-1-knockdown cells of SH-SY5Y and NIH3T3 cells, indicating that the effect of the compounds is specific to DJ-1. These compounds inhibited production of reactive oxygen species and restored activities of mitochondrial complex I and tyrosine hydroxylase that had been compromised by oxidative stress. These compounds prevented dopaminergic cell death in the substantia nigra and restored movement abnormality in 6-hydroxyldopamine-injected PD model rats. One mechanism of action of these compounds is prevention of superfluous oxidation of DJ-1, and the compounds passed through the blood-brain barrier in vitro. Taken together, the results indicate that these compounds should become fundamental drugs for PD therapy.

  15. Maternal obesity and congenital heart defects: a population-based study123

    PubMed Central

    Mills, James L; Troendle, James; Conley, Mary R; Carter, Tonia; Druschel, Charlotte M

    2010-01-01

    Background: Obesity affects almost one-third of pregnant women and causes many complications, including neural tube defects. It is not clear whether the risk of congenital heart defects, the most common malformations, is also increased. Objective: This study was conducted to determine whether obesity is associated with an increased risk of congenital heart defects. Design: A population-based, nested, case-control study was conducted in infants born with congenital heart defects and unaffected controls from the cohort of all births (n = 1,536,828) between 1993 and 2003 in New York State, excluding New York City. The type of congenital heart defect, maternal body mass index (BMI; in kg/m2), and other risk factors were obtained from the Congenital Malformations Registry and vital records. Mothers of 7392 congenital heart defect cases and 56,304 unaffected controls were studied. Results: All obese women (BMI ≥ 30) were significantly more likely than normal-weight women (BMI: 19–24.9) to have children with a congenital heart defect [odds ratio (OR): 1.15; 95% CI: 1.07, 1.23; P < 0.0001]. Overweight women were not at increased risk (OR: 1.00; 95% CI: 0.94, 1.06). The risk in morbidly obese women (BMI ≥ 40) was higher (OR: 1.33; 95% CI: 1.15, 1.54; P = 0.0001) than that in obese women with a BMI of 30–39.9 (OR: 1.11; 95% CI: 1.04, 1.20; P = 0.004). There was a highly significant trend of increasing OR for congenital heart defects with increasing maternal obesity (P < 0.0001). The offspring of obese women had significantly higher ORs for atrial septal defects, hypoplastic left heart syndrome, aortic stenosis, pulmonic stenosis, and tetralogy of Fallot. Conclusions: Obese, but not overweight, women are at significantly increased risk of bearing children with a range of congenital heart defects, and the risk increases with increasing BMI. Weight reduction as a way to reduce risk should be investigated. PMID:20375192

  16. Ab initio study of dopant-defect interactions in graphene sheets and graphene nano-ribbons

    NASA Astrophysics Data System (ADS)

    Tawalbeh, Tarek

    Theoretical studies of nanostructured systems, such as doped, defective and pristine graphene and graphene nanoribbons, present a major challenge to conventional computational methods. This thesis presents ab initio calculations based on density functional theory (DFT) to study the structural and electronic properties of doped and defective graphene and graphene 'nanoribbons. Our calculations are carried-out using density-functional pseudopotential approximations combined with the generalized gradient approximation (GGA) for the exchange-correlation functional. Structural optimizations are executed by iterative force minimization using the conjugate gradient algorithm. We investigate the effect of dopants and point defects on graphene and graphene nanoribbons and study the interactions between the two. Binding energies, equilibrium geometries, charge transfer, and exchange-splitting-induced magnetism are calculated. The dependence of dopant-defect separation distance on interaction energy and interaction energy is examined in detail. We find that the interaction energy for on-defect dopant sites is dominated by how well defect geometry accommodates the dopant-carbon interatomic distance. Depending on the site dopant-defect interaction is either attractive or repulsive. Stone-Wales defect-nitrogen pairing was found to induce exchange splitting and magnetism in certain configurations. Nitrogen was also found to passivate single-vacancy dangling bonds and eliminate exchange-splitting induced magnetism; vacancy-nitrogen interactions were found to be mostly attractive. Boron-vacancy pairing can result in a favorable symmetric sp3 configuration, this is the only vacancy-boron pairing were dangling bonds are passivated and magnetism is eliminated; other favorable boron-vacancy pairings maintain exchange splitting and can in some cases enhance it. We found that the effect of dopant-defect separation distance follows a simple inverse power law. Our results indicate that

  17. U.S. Centers for Disease Control and Prevention and Environmental Protection Agency Urge Commonwealth of Puerto Rico to Consider Aerial Spraying as Part of Integrated Mosquito Control to Reduce Zika-Associated Birth Defects

    EPA Pesticide Factsheets

    EPA News Release: U.S. Centers for Disease Control and Prevention and Environmental Protection Agency Urge Commonwealth of Puerto Rico to Consider Aerial Spraying as Part of Integrated Mosquito Control to Reduce Zika-Associated Birth Defects

  18. Genome-Wide Association Study of Down Syndrome-Associated Atrioventricular Septal Defects

    PubMed Central

    Ramachandran, Dhanya; Zeng, Zhen; Locke, Adam E.; Mulle, Jennifer G.; Bean, Lora J.H.; Rosser, Tracie C.; Dooley, Kenneth J.; Cua, Clifford L.; Capone, George T.; Reeves, Roger H.; Maslen, Cheryl L.; Cutler, David J.; Feingold, Eleanor; Sherman, Stephanie L.; Zwick, Michael E.

    2015-01-01

    The goal of this study was to identify the contribution of common genetic variants to Down syndrome−associated atrioventricular septal defect, a severe heart abnormality. Compared with the euploid population, infants with Down syndrome, or trisomy 21, have a 2000-fold increased risk of presenting with atrioventricular septal defects. The cause of this increased risk remains elusive. Here we present data from the largest heart study conducted to date on a trisomic background by using a carefully characterized collection of individuals from extreme ends of the phenotypic spectrum. We performed a genome-wide association study using logistic regression analysis on 452 individuals with Down syndrome, consisting of 210 cases with complete atrioventricular septal defects and 242 controls with structurally normal hearts. No individual variant achieved genome-wide significance. We identified four disomic regions (1p36.3, 5p15.31, 8q22.3, and 17q22) and two trisomic regions on chromosome 21 (around PDXK and KCNJ6 genes) that merit further investigation in large replication studies. Our data show that a few common genetic variants of large effect size (odds ratio >2.0) do not account for the elevated risk of Down syndrome−associated atrioventricular septal defects. Instead, multiple variants of low-to-moderate effect sizes may contribute to this elevated risk, highlighting the complex genetic architecture of atrioventricular septal defects even in the highly susceptible Down syndrome population. PMID:26194203

  19. Defect-related internal dissipation in mechanical resonators and the study of coupled mechanical systems.

    SciTech Connect

    Friedmann, Thomas Aquinas; Czaplewski, David A.; Sullivan, John Patrick; Modine, Normand Arthur; Wendt, Joel Robert; Aslam, Dean (Michigan State University, Lansing, MI); Sepulveda-Alancastro, Nelson (University of Puerto Rico, Mayaguez, PR)

    2007-01-01

    Understanding internal dissipation in resonant mechanical systems at the micro- and nanoscale is of great technological and fundamental interest. Resonant mechanical systems are central to many sensor technologies, and microscale resonators form the basis of a variety of scanning probe microscopies. Furthermore, coupled resonant mechanical systems are of great utility for the study of complex dynamics in systems ranging from biology to electronics to photonics. In this work, we report the detailed experimental study of internal dissipation in micro- and nanomechanical oscillators fabricated from amorphous and crystalline diamond materials, atomistic modeling of dissipation in amorphous, defect-free, and defect-containing crystalline silicon, and experimental work on the properties of one-dimensional and two-dimensional coupled mechanical oscillator arrays. We have identified that internal dissipation in most micro- and nanoscale oscillators is limited by defect relaxation processes, with large differences in the nature of the defects as the local order of the material ranges from amorphous to crystalline. Atomistic simulations also showed a dominant role of defect relaxation processes in controlling internal dissipation. Our studies of one-dimensional and two-dimensional coupled oscillator arrays revealed that it is possible to create mechanical systems that should be ideal for the study of non-linear dynamics and localization.

  20. Genome-Wide Association Study of Down Syndrome-Associated Atrioventricular Septal Defects.

    PubMed

    Ramachandran, Dhanya; Zeng, Zhen; Locke, Adam E; Mulle, Jennifer G; Bean, Lora J H; Rosser, Tracie C; Dooley, Kenneth J; Cua, Clifford L; Capone, George T; Reeves, Roger H; Maslen, Cheryl L; Cutler, David J; Feingold, Eleanor; Sherman, Stephanie L; Zwick, Michael E

    2015-07-20

    The goal of this study was to identify the contribution of common genetic variants to Down syndrome-associated atrioventricular septal defect, a severe heart abnormality. Compared with the euploid population, infants with Down syndrome, or trisomy 21, have a 2000-fold increased risk of presenting with atrioventricular septal defects. The cause of this increased risk remains elusive. Here we present data from the largest heart study conducted to date on a trisomic background by using a carefully characterized collection of individuals from extreme ends of the phenotypic spectrum. We performed a genome-wide association study using logistic regression analysis on 452 individuals with Down syndrome, consisting of 210 cases with complete atrioventricular septal defects and 242 controls with structurally normal hearts. No individual variant achieved genome-wide significance. We identified four disomic regions (1p36.3, 5p15.31, 8q22.3, and 17q22) and two trisomic regions on chromosome 21 (around PDXK and KCNJ6 genes) that merit further investigation in large replication studies. Our data show that a few common genetic variants of large effect size (odds ratio >2.0) do not account for the elevated risk of Down syndrome-associated atrioventricular septal defects. Instead, multiple variants of low-to-moderate effect sizes may contribute to this elevated risk, highlighting the complex genetic architecture of atrioventricular septal defects even in the highly susceptible Down syndrome population.

  1. Structural birth defects associated with neural tube defects in Hawai'i from 1986 until 2001.

    PubMed

    Forrester, Mathias B; Merz, Ruth D

    2007-09-01

    Using birth defects registry data, this study identified birth defects associated with anencephaly, spina bifida, and encephalocele. Musculoskeletal defects were associated with anencephaly; central nervous system defects, gastrointestinal atresia/stenosis, genitourinary system defects, and musculoskeletal system defects with spina bifida; and central nervous system defects, respiratory defects, oral clefts, genitourinary system defects, and musculoskeletal system defects with encephalocele.

  2. Preventing Fetal Alcohol Syndrome and Other Alcohol-Related Birth Defects: Teacher's Manual and Student Text. High School Edition.

    ERIC Educational Resources Information Center

    Howard, Elizabeth; And Others

    This teacher's manual presents lesson plans for a high-school instructional unit on Fetal Alcohol Syndrome and its less severe manifestations, Alcohol-Related Birth Defects. The lessons cover alcohol's effects during pregnancy, the history of concern about alcohol's effects, consequences of alcohol use in pregnancy, lifestyle risk reduction, and…

  3. Preventing Fetal Alcohol Syndrome and Other Alcohol-Related Birth Defects: Teacher's Manual and Student Text. High School Edition.

    ERIC Educational Resources Information Center

    Howard, Elizabeth; And Others

    This teacher's manual presents lesson plans for a high-school instructional unit on Fetal Alcohol Syndrome and its less severe manifestations, Alcohol-Related Birth Defects. The lessons cover alcohol's effects during pregnancy, the history of concern about alcohol's effects, consequences of alcohol use in pregnancy, lifestyle risk reduction, and…

  4. New Study Designs | Division of Cancer Prevention

    Cancer.gov

    The Division of Cancer Prevention is expanding clinical research beyond standard trial designs to find interventions that may play a role in more than one prevalent disease. | The Division of Cancer Prevention is expanding clinical research beyond standard trial designs to find interventions that may play a role in more than one prevalent disease.

  5. [Awareness and knowledge of the use of folic acid in the prevention of neural tube defects: a survey of women living in Santiago, Chile].

    PubMed

    Pardo V, Rosa A; Lay-Son R, Guillermo; Aranda Ch, Waldo; Dib M, Martín; Espina M, Pablo; Muñoz K, María J; Muñoz B, Pilar; Navarrete C, María F; Ojeda M, Natalia V; Parra, Jorge; Rebolledo D, Cristian A; Recabal G, Pedro; Tenhamm T, Tamara

    2007-12-01

    Wheat flour in Chile is fortified with folie acid and pregnant women are also supplemented with the vitamin, but the population level of knowledge or awareness about this vitamin and its use by pregnant women is unknown. To assess the level of knowledge that postpartum women from Santiago de Chile have about folic acid. A questionnaire about folic acid and its effects on the prevention of neural tube defects was developed adapting questionnaires designed abroad. It was applied by medical students to puerperal women, hospitalized in public hospitals. The questionnaire was applied to 342 women aged 26 +/- 7 years. Sixty one percent were housewives and 55% completed high school education. Forty seven percent of these women had heard about folic acid, 9.6% knew that it was able to prevent congenital defects and only one received an adequate supplementation during pregnancy. Women aged 25 to 34 years and those with an adequate medical care during pregnancy had a significantly better knowledge about folic acid and its role in the prevention of congenital anomalies. The more common means to receive information about folic acid were midwives (34%), mass media (28%) and doctors (20%). Two hundred eleven women (62%) agreed to take folic acid in a future gestation and 58% preferred to do so using fortified foods. Post partum women from Santiago have a poor knowledge about the relevance of folic acid supplementation.

  6. Autologous serum eyedrops for dry eyes and epithelial defects: clinical and in vitro toxicity studies

    PubMed Central

    Poon, A.; Geerling, G.; Dart, J.; Fraenkel, G.; Daniels, J.

    2001-01-01

    BACKGROUND/AIMS—Autologous serum drops have been reported to be beneficial in keratoconjunctivitis sicca (KCS) and persistent epithelial defects (PED). A clinical pilot study was carried out to examine these potential uses and in vitro toxicity testing on corneal epithelial cell cultures was performed to compare the effect of serum drops with unpreserved hypromellose (hydroxypropylmethylcellulose 0.3%).
METHODS—Patients with KCS and PED, unresponsive to conventional treatment were recruited. Patients were examined before treatment, at 1 and 2 weeks after initiation, and then 2 weekly until treatment ceased. Symptoms were assessed at each visit. Clinical examination included Schirmer's test without anaesthesia, rose bengal staining, and fluorescein staining. Epithelial defects were measured with the slit beam. In the laboratory, cultured human corneal epithelial cells were exposed to serum drops and hypromellose, and their viability evaluated with fluorescent viability staining (Calcein AM ethidium homodimer) and an ATP assay.
RESULTS—Autologous serum was used in 15 eyes of 13 patients with PED and 11 eyes of nine patients with KCS. In two patients serum drops were started after penetrating keratoplasty (PK). The PKs were performed for perforations secondary to PEDs. Of the 15 eyes with PED, nine healed at a mean of 29 days and six failed. The mean duration of PED before the use of serum drops was 48.2 days. Of the 11 eyes with KCS, six had improved subjective scores and fluorescein scores, and five had improved rose bengal scores after the use of serum drops. For the two patients who used serum eyedrops post-PK, there was a stable and intact epithelium at 1 week. Cessation of serum drops during the postoperative period led to deterioration in the subjective and objective scores in both patients. One developed a PED that responded to reinstitution of serum drops. The morphology and ATP levels of cultured epithelial cells exposed to serum were

  7. Craniofacial birth defects: The role of neural crest cells in the etiology and pathogenesis of Treacher Collins syndrome and the potential for prevention.

    PubMed

    Trainor, Paul A

    2010-12-01

    Of all the babies born with birth defects, approximately one-third display anomalies of the head and face [Gorlin et al., 1990] including cleft lip, cleft palate, small or absent facial and skull bones and improperly formed nose, eyes, ears, and teeth. Craniofacial disorders are a primary cause of infant mortality and have serious lifetime functional, esthetic, and social consequences that are devastating to both children and parents alike. Comprehensive surgery, dental care, psychological counseling, and rehabilitation can help ameliorate-specific problems but at great cost over many years which dramatically affects national health care budgets. For example, the Center for Disease Control and Prevention estimates that the lifetime cost of treating the children born each year with cleft lip and/or cleft palate alone to be US$697 million. Treating craniofacial malformations, of which in excess of 700 distinct syndromes have been described, through comprehensive, well-coordinated and integrated strategies can provide satisfactory management of individual conditions, however, the results are often variable and rarely fully corrective. Therefore, better techniques for tissue repair and regeneration need to be developed and therapeutic avenues of prevention need to be explored in order to eliminate the devastating consequences of head and facial birth defects. To do this requires a thorough understanding of the normal events that control craniofacial development during embryogenesis. This review therefore focuses on recent advances in our understanding of the basic etiology and pathogenesis of a rare craniofacial disorder known as Treacher Collins syndrome and emerging prospects for prevention that may have broad application to congenital craniofacial birth defects.

  8. Craniofacial Birth Defects: The Role of Neural Crest Cells in the Etiology and Pathogenesis of Treacher Collins Syndrome and the Potential for Prevention

    PubMed Central

    Trainor, Paul A.

    2013-01-01

    Of all the babies born with birth defects, approximately one-third display anomalies of the head and face [Gorlin et al., 1990] including cleft lip, cleft palate, small or absent facial and skull bones and improperly formed nose, eyes, ears, and teeth. Craniofacial disorders are a primary cause of infant mortality and have serious lifetime functional, esthetic, and social consequences that are devastating to both children and parents alike. Comprehensive surgery, dental care, psychological counseling, and rehabilitation can help ameliorate-specific problems but at great cost over many years which dramatically affects national health care budgets. For example, the Center for Disease Control and Prevention estimates that the lifetime cost of treating the children born each year with cleft lip and/or cleft palate alone to be US$697 million. Treating craniofacial malformations, of which in excess of 700 distinct syndromes have been described, through comprehensive, well-coordinated and integrated strategies can provide satisfactory management of individual conditions, however, the results are often variable and rarely fully corrective. Therefore, better techniques for tissue repair and regeneration need to be developed and therapeutic avenues of prevention need to be explored in order to eliminate the devastating consequences of head and facial birth defects. To do this requires a thorough understanding of the normal events that control craniofacial development during embryogenesis. This review therefore focuses on recent advances in our understanding of the basic etiology and pathogenesis of a rare craniofacial disorder known as Treacher Collins syndrome and emerging prospects for prevention that may have broad application to congenital craniofacial birth defects. PMID:20734335

  9. Laron's Dwarfism: Studies on the Nature of the Defect

    ERIC Educational Resources Information Center

    Elders, M. Joycelyn; And Others

    1973-01-01

    Laron's syndrome, characterized by severe dwarfism, high circulating levels of immunoreactive growth hormone, and failure to generate somatomedin after administration of human growth hormone, was studied in a boy 7 1/2 years of age. (MC)

  10. Dementia in Ageing Mental Defectives: A Clinical and Neuropathological Study.

    ERIC Educational Resources Information Center

    Reid, A. H.; And Others

    1978-01-01

    The study was aimed at establishing the prevalence and clinical features of the psychoses of senescence (senile, presenile, and cerebral arteriosclerotic dementias) in 155 mentally retarded patients over the age of 45. (SBH)

  11. Laron's Dwarfism: Studies on the Nature of the Defect

    ERIC Educational Resources Information Center

    Elders, M. Joycelyn; And Others

    1973-01-01

    Laron's syndrome, characterized by severe dwarfism, high circulating levels of immunoreactive growth hormone, and failure to generate somatomedin after administration of human growth hormone, was studied in a boy 7 1/2 years of age. (MC)

  12. Defective Infant Formulas and Expressive Language Problems: A Case Study.

    ERIC Educational Resources Information Center

    Wing, Clara S.

    1990-01-01

    Children who used chloride-deficient soy-based infant formulas (Neo-Mull-Soy and Cho-Free) have been found to exhibit expressive language disorders. Medical studies of such children are reviewed, and a case study compares the language development deficits of an eight-year-old boy who used the formula with that of his fraternal twin who did not.…

  13. First-Principles Study of Defects in GaN, AlN and Their Alloys

    DTIC Science & Technology

    2010-08-31

    studied the similar type of pairs in GaN, i.e. Gai -VGa. These types of defect complexes are called Frenkel pairs which are believed to form when the...defects have been carried out.[17-21] In our previous program, we studied the GaGa i V− pairs in GaN. We found that Gai can occur in 3+, 2+, and 1...charge states, depending on the Fermi energy of the sample. VGa can occur in 3−, 2−, 1−, and neutral charge states. Because Gai and VGa have

  14. Basic Study of Detecting Defects in Solid Materials Using High-Intensity Aerial Ultrasonic Waves

    NASA Astrophysics Data System (ADS)

    Osumi, Ayumu; Kobayashi, Hiromasa; Ito, Youichi

    2012-07-01

    Recently, developments have improved methods employing aerial ultrasonic waves for detecting defects in solid materials such as metals, pipe walls, and fiber-reinforced plastics. These methods can be performed using a noncontacting aerial ultrasonic probe. In a previous study, we developed a new method using high-intensity aerial ultrasonic waves to successfully detect peeling, artificially created by inserting an air gap between tiles and concrete plates. In the present study, we use the same method to detect the depth and size of defects in a homogeneous medium.

  15. Optical lattices as a tool to study defect-induced superfluidity

    NASA Astrophysics Data System (ADS)

    Astrakharchik, Grigory E.; Krutitsky, Konstantin V.; Lewenstein, Maciej; Mazzanti, Ferran; Boronat, Jordi

    2017-09-01

    We study the superfluid response, the energetic and structural properties of a one-dimensional ultracold Bose gas in an optical lattice of arbitrary strength. We use the Bose-Fermi mapping in the limit of infinitely large repulsive interaction and the diffusion Monte Carlo method in the case of finite interaction. For slightly incommensurate fillings we find a superfluid behavior, which is discussed in terms of vacancies and interstitials. It is shown that both the excitation spectrum and static structure factor are different for the cases of microscopic and macroscopic fractions of defects. This system provides an extremely well-controlled model for studying defect-induced superfluidity.

  16. Light Activated Copper Defects in P-Type Silicon Studied by PCD

    NASA Astrophysics Data System (ADS)

    Yli-Koski, M.; Väinölä, H.; Haarahiltunen, A.; Storgårds, J.; Saarnilehto, E.; Sinkkonen, J.

    2004-01-01

    We have studied copper defects in p-type silicon by measuring its precipitation kinetics by means of the microwave photoconductive decay (µPCD) technique. Copper atoms precipitated during high intensity light treatment at room temperature. We used the total reflection X-ray fluorescence (TXRF) and the transient ion drift (TID) techniques to determine the bulk concentration of copper. We estimated the density and the radius of the copper precipitates as well as the average capture cross-section for precipitated copper atoms from the measured copper precipitation time constant, bulk concentration of copper, and the change in the recombination rate. We also studied how the density of oxygen defect affects the copper precipitation. Our results show that copper precipitates at two different kinds of defects.

  17. (Defect studies in III-V thin film semiconductors)

    SciTech Connect

    Not Available

    1991-01-01

    Our primary research objective in 90/91 has been to continue studying misfit dislocation confinement by patterning substrates into mesas before the epitaxial growth of strained layers. This report presents progress for many of the areas of our research. (JL)

  18. A comprehensive evaluation of food fortification with folic acid for the primary prevention of neural tube defects.

    PubMed

    Liu, Shiliang; West, Roy; Randell, Edward; Longerich, Linda; O'connor, Kathleen Steel; Scott, Helen; Crowley, Marian; Lam, Angeline; Prabhakaran, Victor; McCourt, Catherine

    2004-09-27

    BACKGROUND: Periconceptional use of vitamin supplements containing folic acid reduces the risk of a neural tube defect (NTD). In November 1998, food fortification with folic acid was mandated in Canada, as a public health strategy to increase the folic acid intake of all women of childbearing age. We undertook a comprehensive population based study in Newfoundland to assess the benefits and possible adverse effects of this intervention. METHODS: This study was carried out in women aged 19-44 years and in seniors from November 1997 to March 1998, and from November 2000 to March 2001. The evaluation was comprised of four components: I) Determination of rates of NTDs; II) Dietary assessment; III) Blood analysis; IV) Assessment of knowledge and use of folic acid supplements. RESULTS: The annual rates of NTDs in Newfoundland varied greatly between 1976 and 1997, with a mean rate of 3.40 per 1,000 births. There was no significant change in the average rates between 1991-93 and 1994-97 (relative risk [RR] 1.01, 95% confidence interval [CI] 0.76-1.34). The rates of NTDs fell by 78% (95% CI 65%-86%) after the implementation of folic acid fortification, from an average of 4.36 per 1,000 births during 1991-1997 to 0.96 per 1,000 births during 1998-2001 (RR 0.22, 95% CI 0.14-0.35). The average dietary intake of folic acid due to fortification was 70 μg/day in women aged 19-44 years and 74 μg/day in seniors. There were significant increases in serum and RBC folate levels for women and seniors after mandatory fortification. Among seniors, there were no significant changes in indices typical of vitamin B12 deficiencies, and no evidence of improved folate status masking haematological manifestations of vitamin B12 deficiency. The proportion of women aged 19-44 years taking a vitamin supplement containing folic acid increased from 17% to 28%. CONCLUSIONS: Based on these findings, mandatory food fortification in Canada should continue at the current levels. Public education

  19. The role of point defects in PbS, PbSe and PbTe: a first principles study

    NASA Astrophysics Data System (ADS)

    Li, Wun-Fan; Fang, Chang-Ming; Dijkstra, Marjolein; van Huis, Marijn A.

    2015-08-01

    Intrinsic defects are of central importance to many physical and chemical processes taking place in compound nanomaterials, such as photoluminescence, accommodation of off-stoichiometry and cation exchange. Here, the role of intrinsic defects in the above mentioned processes inside rock salt (RS) lead chalcogenide systems PbS, PbSe and PbTe (PbX) was studied systematically using first principles density functional theory. Vacancy, interstitial, Schottky and Frenkel defects were considered. Rock salt PbO was included for comparison. The studied physical properties include defect formation energy, local geometry relaxation, Bader charge analysis, and electronic structure. The defect formation energies show that monovacancy defects and Schottky defects are favoured over interstitial and Frenkel defects. Schottky dimers, where the cation vacancy and anion vacancy are adjacent to each other, have the lowest defect formation energies at 1.27 eV, 1.29 eV and 1.21 eV for PbS, PbSe and PbTe, respectively. Our results predict that a Pb monovacancy gives rise to a shallow acceptor state, while an X vacancy generates a deep donor state, and Schottky defects create donor-acceptor pairs inside the band gap. The surprisingly low formation energy of Schottky dimers suggests that they may play an important role in cation exchange processes, in contrast to the current notion that only single point defects migrate during cation exchange.

  20. The role of point defects in PbS, PbSe and PbTe: a first principles study.

    PubMed

    Li, Wun-Fan; Fang, Chang-Ming; Dijkstra, Marjolein; van Huis, Marijn A

    2015-09-09

    Intrinsic defects are of central importance to many physical and chemical processes taking place in compound nanomaterials, such as photoluminescence, accommodation of off-stoichiometry and cation exchange. Here, the role of intrinsic defects in the above mentioned processes inside rock salt (RS) lead chalcogenide systems PbS, PbSe and PbTe (PbX) was studied systematically using first principles density functional theory. Vacancy, interstitial, Schottky and Frenkel defects were considered. Rock salt PbO was included for comparison. The studied physical properties include defect formation energy, local geometry relaxation, Bader charge analysis, and electronic structure. The defect formation energies show that monovacancy defects and Schottky defects are favoured over interstitial and Frenkel defects. Schottky dimers, where the cation vacancy and anion vacancy are adjacent to each other, have the lowest defect formation energies at 1.27 eV, 1.29 eV and 1.21 eV for PbS, PbSe and PbTe, respectively. Our results predict that a Pb monovacancy gives rise to a shallow acceptor state, while an X vacancy generates a deep donor state, and Schottky defects create donor-acceptor pairs inside the band gap. The surprisingly low formation energy of Schottky dimers suggests that they may play an important role in cation exchange processes, in contrast to the current notion that only single point defects migrate during cation exchange.

  1. HgCdTe Surface and Defect Study Program.

    DTIC Science & Technology

    1983-07-01

    the blockage of UV as mentioned above, except in the case of pressures, above I Torr. RPT40497 25 SBRC: --- -- -- -- - Another important consideration...as "independent" entities as is the case (to the first approximation) with all other semiconductors studied to date. These results have given rise to...all cases but one (Prof. Walter Harrison’s invited paper on the theory of bonding in MCT) have been written up as full articles for the conference

  2. High-temperature study of defects and homogeneity in glass

    NASA Astrophysics Data System (ADS)

    Yoon, Chang Hyun

    Glass frit has many useful applications in the glass and ceramic industries. Several attempts were made in this study to understand the origin of problems that generally occur when using glass frit. The effect of water/glass interactions on the rheology of glass suspension and the final properties of glass and glaze were studied. The dissolution of refractory inclusions and its influence on the bubble evolution, glass structure, and homogeneity of the resulting melt were also studied. The effects of long-term interaction of water with various frit suspensions were considered. The change in suspension rheology is associated with the ion concentration of the frit suspension, which strongly depends on the frit composition, additives, and solid content of frit suspension. Physical property and compositional variations resulted from dealkalization reactions between the frit particles and water. New investigative techniques for continuous monitoring and quantitative analysis of the dissolution of refractory inclusions in glass have been developed utilizing high-temperature microscopy with computer image analysis. The dissolution rates of refractory oxides in glass frit were measured utilizing hot-stage microscopy in the temperature range from 1050°C to 1400°C. The effects of dissolution on the structure of the final glass, were monitored by infrared spectroscopy. Homogenization of the resulting melts was studied using a Christiansen filter. It was found that melting temperature and time strongly influence the dissolution of refractory batch materials and subsequent homogenization rates, leading to large differences in final structures for glass melts and glazes which have not attained equilibrium.

  3. Diamond Deposition and Defect Chemistry Studied via Solid State NMR

    DTIC Science & Technology

    1994-06-30

    same integrated NMR signal, regardless of its chemical environment, provided complete spin-lattice relaxation occurs between averages 3 . Gem -quality...occurs between averages, and broadening from years, a large research effort has been devoted to the study paramagnetic centers is insignificant. Gem ...information on the distribution and motion mond’s durability very attractive. However, while gem - of hydrogen can be obtained from the solid-state NMR

  4. Study of the nature of extended defects of copper oxide

    NASA Astrophysics Data System (ADS)

    Kryukova, G. N.; Zaikovskii, V. I.; Sadykov, V. A.; Tikhov, S. F.; Popovskii, V. V.; Bulgakov, N. N.

    1988-05-01

    A sample of powdered copper oxide suitable for studying its real structure with the help of electron microscopy was prepared by slow decomposition of copper nitrate. It is shown that in particles of oxide there are (001) and (100) twins and screw dislocations with Burgers vector along <010>. The lattice of CuO near the twins is strongly deformed. The structures of the composition planes for both types of twins as well as their relative stabilities are analyzed.

  5. Technology Solutions Case Study: Preventing Thermal Bypass

    SciTech Connect

    none,

    2012-10-01

    This project highlights the importance of continuous air barriers in full alignment with insulation to prevent thermal bypasses and achieve high energy performance, and recommends use of ENERGY STAR's Thermal Bypass Inspection Checklist.

  6. Ab initio simulation study of defect assisted Zener tunneling in GaAs diode

    NASA Astrophysics Data System (ADS)

    Lu, Juan; Fan, Zhi-Qiang; Gong, Jian; Jiang, Xiang-Wei

    2017-06-01

    The band to band tunneling of defective GaAs nano-junction is studied by using the non-equilibrium Green's function formalism with density functional theory. Aiming at performance improvement, two types of defect-induced transport behaviors are reported in this work. By examining the partial density of states of the system, we find the substitutional defect OAs that locates in the middle of tunneling region will introduce band-gap states, which can be used as stepping stones to increase the tunneling current nearly 3 times higher at large bias voltage (Vb≥0.3V). Another type of defects SeAs and VGa (Ga vacancy) create donor and acceptor states at the edge of conduction band (CB) and valence band (VB)respectively, which can change the band bending of the junction as well as increase the tunneling field obtaining a 1.5 times higher ON current. This provides an effective defect engineering approach for next generation TFET device design.

  7. Defect chemistry and electronic transport in low-κ dielectrics studied with electrically detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Mutch, Michael J.; Lenahan, Patrick M.; King, Sean W.

    2016-03-01

    Defect mediated electronic transport phenomena in low-κ dielectric films are of great technological interest for state-of-the-art and next generation microprocessors. At the present time, the leading low-κ interlayer dielectrics and etch-stop layers are based upon a-SiOC:H and a-SiCN:H, respectively. In this study, we utilize electrically detected magnetic resonance (EDMR), a derivative of electron paramagnetic resonance, to provide physical insight into electronic transport, as well as the nature and origin of defects in dense and porous a-SiOC:H and dense a-SiCN:H films. Resonance measurements are performed before and after the removal of sacrificial porogens via UV treatments to understand the role of specific defect centers in electronic transport in a-SiOC:H systems, and the nature of defects created by UV treatments. Unfortunately, a-SiOC:H and a-SiCN:H EDMR spectra are relatively broad and featureless. These featureless spectra are consistent with fairly complex a-SiOC:H and a-SiCN:H systems. We argue that physical insight may be gleaned from featureless spectra via multiple frequency EDMR. Baseline multiple frequency EDMR measurements are performed in a-Si:H and a-C:H to illustrate the nature of line broadening mechanisms of silicon and carbon related defects.

  8. Defective germanene as a high-efficiency helium separation membrane: a first-principles study

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Chang, Xiao; He, Daliang; Xue, Qingzhong; Li, Xiaofang; Jin, Yakang; Zheng, Haixia; Ling, Cuicui

    2017-03-01

    Development of low energy cost membranes for separating helium from natural gas is highly desired. Using van der Waals-corrected first-principles density functional theory (DFT) calculations, we theoretically investigate the helium separation performance of divacancy-defective germanene. The 555 777 divacancy-defective germanene presents a 0.53 eV energy barrier for helium, which is slightly larger than the energy threshold value of gas molecule penetration of a membrane (0.5 eV). Thus, the 555 777 divacancy-defective germanene is difficult for helium to permeate, except under high temperature or pressure. However, the 585 divacancy-defective germanene presents a surmountable energy barrier (0.27 eV) for helium, and it shows extremely high helium selectivities relative to other studied gas molecules. Especially, the He/Ne selectivity can be as high as 1 × 104 at room temperature. Together with the acceptable permeance for helium, the 585 divacancy-defective germanene can be used for helium separation with remarkably good performance.

  9. Defective germanene as a high-efficiency helium separation membrane: a first-principles study.

    PubMed

    Zhu, Lei; Chang, Xiao; He, Daliang; Xue, Qingzhong; Li, Xiaofang; Jin, Yakang; Zheng, Haixia; Ling, Cuicui

    2017-03-01

    Development of low energy cost membranes for separating helium from natural gas is highly desired. Using van der Waals-corrected first-principles density functional theory (DFT) calculations, we theoretically investigate the helium separation performance of divacancy-defective germanene. The 555 777 divacancy-defective germanene presents a 0.53 eV energy barrier for helium, which is slightly larger than the energy threshold value of gas molecule penetration of a membrane (0.5 eV). Thus, the 555 777 divacancy-defective germanene is difficult for helium to permeate, except under high temperature or pressure. However, the 585 divacancy-defective germanene presents a surmountable energy barrier (0.27 eV) for helium, and it shows extremely high helium selectivities relative to other studied gas molecules. Especially, the He/Ne selectivity can be as high as 1 × 10(4) at room temperature. Together with the acceptable permeance for helium, the 585 divacancy-defective germanene can be used for helium separation with remarkably good performance.

  10. Prevention of Defective Placentation and Pregnancy Loss by Blocking Innate Immune Pathways in a Syngeneic Model of Placental Insufficiency.

    PubMed

    Gelber, Shari E; Brent, Elyssa; Redecha, Patricia; Perino, Giorgio; Tomlinson, Stephen; Davisson, Robin L; Salmon, Jane E

    2015-08-01

    Defective placentation and subsequent placental insufficiency lead to maternal and fetal adverse pregnancy outcome, but their pathologic mechanisms are unclear, and treatment remains elusive. The mildly hypertensive BPH/5 mouse recapitulates many features of human adverse pregnancy outcome, with pregnancies characterized by fetal loss, growth restriction, abnormal placental development, and defects in maternal decidual arteries. Using this model, we show that recruitment of neutrophils triggered by complement activation at the maternal/fetal interface leads to elevation in local TNF-α levels, reduction of the essential angiogenic factor vascular endothelial growth factor, and, ultimately, abnormal placentation and fetal death. Blockade of complement with inhibitors specifically targeted to sites of complement activation, depletion of neutrophils, or blockade of TNF-α improves spiral artery remodeling and rescues pregnancies. These data underscore the importance of innate immune system activation in the pathogenesis of placental insufficiency and identify novel methods for treatment of pregnancy loss mediated by abnormal placentation.

  11. PIXE studies of osteoporosis preventive treatments

    NASA Astrophysics Data System (ADS)

    Ynsa, M. D.; Pinheiro, T.; Ager, F. J.; Alves, L. C.; Millán, J. C.; Gómez-Zubelbia, M. A.; Respaldiza, M. A.

    2002-04-01

    Particle induced X-ray emission (PIXE) and nuclear microprobe (NMP) have been used in an exploratory work to study elemental alterations in tissues of experimental animals submitted to osteoporosis preventive treatments. Osteopathologies have been associated with several factors, such as hormonal disturbances, metabolic aberrations, low dietary Ca and vitamin D intake, excess of iron, among other possible factors. Hormonal treatments seem to be beneficial to the incorporation of Ca in bone but breast and endometrial cancers constitute significant side effects that cannot be ignored. Wistar female rats were used to test the effect of estrogen therapy in osteoporosis progression. The variations of elemental concentrations in uterus and the Ca content of femoral bones of ovariectomised rats under estrogen therapy were investigated. PIXE, Rutherford backscattering spectrometry and secondary electron microscopy techniques were applied for the characterisation of biological materials, with respect to morphology and trace element distribution determination. The increase of Ca and Fe concentrations in uterus and the variations for Ca distribution patterns in bone of rats submitted to estrogen therapy were the major features observed.

  12. First-principles study on the effects of the intrinsic defects in GaAs saturable absorber

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyang; Li, Dechun; Zhao, Shengzhi; Cong, Wen; Li, Guiqiu; Yang, Kejian

    2014-11-01

    First-principles calculations are performed for the effects of the intrinsic defects in GaAs saturable absorber, using the state-of-the-art computational method with the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional to correct the band gap. The defect energy levels corresponding to all point defects and their electrical characteristics are analyzed from the aspects of density of states and band structures. Furthermore, the partial band decomposed charge density of the defect bands are also been studied. The relationships between defect energy levels and EL2 deep-level defect will be helpful in ascertaining the origin of the EL2 deep-level defect in GaAs.

  13. Osseointegrated implants and auricular defects: a case series study.

    PubMed

    Wright, Robert F; Zemnick, Candice; Wazen, Jack J; Asher, Eric

    2008-08-01

    The objective of this study was to report on the survival rate of 16 patients treated with extraoral implants in the auricular region, analyze treatment outcomes, and discuss important clinical variables encountered during treatment. Sixteen patients who received extraoral dental implants to retain auricular prostheses between 1987 and 2003 were followed retrospectively. The variables recorded were gender, initial diagnosis, number and size of implants, implant placement date, age at implant placement, history of radiation to the treated field, abutment size, design of initial prosthesis, age of initial prosthesis (when a remake was indicated), date of prosthesis delivery, soft tissue response, grafting procedure, date of last follow-up, and complications. All patients were thoroughly evaluated presurgically by the reconstruction team, which consisted of prosthodontists, a facial prosthetist, and an otolaryngologist. Surgical templates were used for all patients. The criteria for success of the prostheses included marginal accuracy, overall stability and function, symmetry/position, texture, color stability, and patient acceptance. Thirty-nine implants were placed in 16 patients. All 16 patients were completely satisfied with their reconstructions. No surgical complications, implant failures, or prosthetic failures were encountered. Therefore, the survival rate was 100%. Three patients (18.75%) had grade 0, seven (43.75%) had grade 1, five (31.25%) had grade 2, and one (6.25%) had grade 3 soft tissue inflammation. The inflammation completely resolved in 7 of the 13 patients (54%) with hygiene reinforcement or soft tissue reduction. The survival rate for bone-anchored titanium implants and prostheses was 100%. Bone-anchored titanium implants provided the 16 patients in this study with a safe, reliable, adhesive-free method to anchor auricular prostheses with recovery of normal appearance. Under the guidance of an appropriate implant team, proper positioning of

  14. The reduction of radiation damage in space solar cells. A study of radiation defects in silicon (+)

    NASA Astrophysics Data System (ADS)

    Bielle-Daspet, D.; Bourgoin, J.; Bernard, J.; Castaner-Munoz, L.; Pratt, L.; Crabb, R. L.

    1982-06-01

    Research data on space environmental flux and simulation conditions; electron and photon induced defects; measurement techniques for correlated study of the microscopic macroscopic and global (electrical) degradation of the solar cell; and numerical models for space cell and degradation prediction were reviewed. The survey indicates that space factors must include possible contributions of solar flare protons, photon effects and thermal annealing due to the insolation and temperature cycles of the solar generators. An adapted set of measurement techniques must be used in order to obtain comprehensive characterization of defect and solar-cell behavior. In numerical models of solar cell electrical behavior and degradation, cell structure as well as defect and carrier properties must be introduced. In space, P-type silicon should behave better than N-type; lithium in N-type gives improvement only in particular cases, and photon degradation seems to be related to boron doping when carbon and oxygen content are simultaneously low.

  15. An experimental study on the application of radionuclide imaging in repair of the bone defect.

    PubMed

    Zhu, Weimin; Wang, Daping; Zhang, Xiaojun; Lu, Wei; Liu, Jianquan; Peng, Liangquan; Li, Hao; Han, Yun; Zeng, Yanjun

    2011-08-01

    The aim of our study was to validate the effect of radionuclide imaging in early monitoring of the bone's reconstruction, the animal model of bone defect was made on the rabbits repaired with HA artificial bone. The ability of bone defect repair was evaluated by using radionuclide bone imaging at 2, 4, 8 and 12 weeks postoperatively. The results indicate that the experimental group stimulated more bone formation than that of the control group. The differences of the bone reconstruction ability were statistically significant (p<0.05). The nano-HA artificial has good bone conduction, and it can be used for the treatment of bone defects. Radionuclide imaging may be an effective and first choice method for the early monitoring of the bone's reconstruction.

  16. Study of defect formation from process step anomalies in limited boron source diffusion in crystalline silicon

    SciTech Connect

    Singha, Bandana Solanki, Chetan Singh

    2016-05-06

    In limited dopant source diffusion process, the deposition and the drive in conditions of the source play an important role in pn- junction formation. The pre diffusion anomalies can introduce defects in the emitter region during the process of diffusion which can glide into the bulk region. So, the defects formed in the emitter region due to different pre diffusion issues are studied in this work with boron spin on dopant source diffused in n-type crystalline Si. The samples are prepared for different diffusion conditions of times carried out at diffusion temperature of 900°C. Different characterization techniques used in this work confirms the presence of these defects in the emitter region. The dopant distribution under the same diffusion condition result in non- uniformity, varying the junction depth of the emitter. A single process step anomaly is sufficient enough to degrade the emitter performance and should be avoided.

  17. Study of defect formation from process step anomalies in limited boron source diffusion in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Singha, Bandana; Solanki, Chetan Singh

    2016-05-01

    In limited dopant source diffusion process, the deposition and the drive in conditions of the source play an important role in pn- junction formation. The pre diffusion anomalies can introduce defects in the emitter region during the process of diffusion which can glide into the bulk region. So, the defects formed in the emitter region due to different pre diffusion issues are studied in this work with boron spin on dopant source diffused in n-type crystalline Si. The samples are prepared for different diffusion conditions of times carried out at diffusion temperature of 900°C. Different characterization techniques used in this work confirms the presence of these defects in the emitter region. The dopant distribution under the same diffusion condition result in non- uniformity, varying the junction depth of the emitter. A single process step anomaly is sufficient enough to degrade the emitter performance and should be avoided.

  18. First principles study of phosphorus and boron defects in Si-XII

    NASA Astrophysics Data System (ADS)

    Malone, Brad D.; Cohen, Marvin L.

    2011-03-01

    We present a first-principles study of phosphorus and boron substitutional defects in Si-XII, a polytype of silicon in the R8 structure. Recent results from nanoindentation experiments reveal that this phase is semiconducting and has the interesting property that it can be doped n- and p-type at room temperature without an annealing step. We examine the formation energies of the B and P defects at the two distinct atomic sites in the R8 structure. We also calculate the thermodynamic transition levels of each defect in its relevant charge states. This work was supported by National Science Foundation Grant No. DMR10-1006184, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by the Lawrencium cluster at LBNL.

  19. An experimental study on the application of radionuclide imaging in repair of the bone defect

    PubMed Central

    Zhu, Weimin; Wang, Daping; Zhang, Xiaojun; Lu, Wei; Liu, Jianquan; Peng, Liangquan; Li, Hao; Han, Yun; Zeng, Yanjun

    2011-01-01

    The aim of our study was to validate the effect of radionuclide imaging in early monitoring of the bone’s reconstruction, the animal model of bone defect was made on the rabbits repaired with HA artificial bone. The ability of bone defect repair was evaluated by using radionuclide bone imaging at 2, 4, 8 and 12 weeks postoperatively. The results indicate that the experimental group stimulated more bone formation than that of the control group. The differences of the bone reconstruction ability were statistically significant (p<0.05). The nano-HA artificial has good bone conduction, and it can be used for the treatment of bone defects. Radionuclide imaging may be an effective and first choice method for the early monitoring of the bone’s reconstruction. PMID:21875418

  20. Positron-annihilation 2D-ACAR studies of disordered and defected alloys

    SciTech Connect

    Bansil, A.; Prasad, R.; Smedskjaer, L.C.; Benedek, R.; Mijnarends, P.E.

    1987-09-01

    Theoretical and experimental progess in connection with 2D-ACAR positron annihilation studies of ordered, disordered, and defected alloys is discussed. We present, in particular, some of the recent developments concerning the electronic structure of disordered alloys, and the work in the area of annihilation from positrons trapped at vacancy-type defects in metals and alloys. The electronic structure and properties of a number of compounds are also discussed briefly; we comment specifically on high T/sub c/ ceramic superconductors, Heusler alloys, and transition-metal aluminides. 58 refs., 116 figs.

  1. Signal to Noise Studies on Thermographic Data with Fabricated Defects for Defense Structures

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Rajic, Nik; Genest, Marc

    2006-01-01

    There is a growing international interest in thermal inspection systems for asset life assessment and management of defense platforms. The efficacy of flash thermography is generally enhanced by applying image processing algorithms to the observations of raw temperature. Improving the defect signal to noise ratio (SNR) is of primary interest to reduce false calls and allow for easier interpretation of a thermal inspection image. Several factors affecting defect SNR were studied such as data compression and reconstruction using principal component analysis and time window processing.

  2. Signal to noise studies on thermographic data with fabricated defects for defense structures

    NASA Astrophysics Data System (ADS)

    Zalameda, Joseph N.; Rajic, Nik; Genest, Marc

    2006-04-01

    There is a growing international interest in thermal inspection systems for asset life assessment and management of defense platforms. The efficacy of flash thermography is generally enhanced by applying image processing algorithms to the observations of raw temperature. Improving the defect signal to noise ratio (SNR) is of primary interest to reduce false calls and allow for easier interpretation of a thermal inspection image. Several factors affecting defect SNR were studied such as data compression and reconstruction using principal component analysis and time window processing.

  3. Birth Defects. Matrix No. 2.

    ERIC Educational Resources Information Center

    Brent, Robert L.

    This report discusses the magnitude of the problem of birth defects, outlines advances in the birth defects field in the past decade, and identifies those areas where research is needed for the prevention, treatment, and management of birth defects. The problem of birth defects has consumed a greater portion of our health care resources because of…

  4. Profile and risk factors for congenital heart defects: A study in a tertiary care hospital

    PubMed Central

    Abqari, Shaad; Gupta, Akash; Shahab, Tabassum; Rabbani, MU; Ali, S Manazir; Firdaus, Uzma

    2016-01-01

    Introduction: Congenital heart defects (CHDs) are an important cause of mortality and morbidity in children representing a major global health burden. It is thus important to determine their prevalence and spectrum and identify risk factors associated with the development of heart defects. Materials and Methods: A case-control study was carried out in the Department of Pediatrics and Center of Cardiology, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India, from February 2014 to August 2015. All patients referred with complaints or clinical examination suggestive of CHDs were further evaluated with echocardiography. On Echocardiography, patients having CHDs were included as cases and those having a normal echocardiographic study were included as controls. Healthy controls were also included. 400 cases and 400 controls were thus identified; preterms having patent ductus arteriosus and patent foramen ovale and those with acquired heart defects were excluded. Risk factors among cases and controls were further studied. Results: Acyanotic heart defects were 290 (72.50%) of the total heart defects, whereas the contribution of cyanotic heart defects was 110 (27.50%). Out of all CHDs, ventricular septal defect was the most common lesion with contribution of 152 (38%) cases, whereas among the cyanotic heart defects, Tetralogy of Fallot was the most common lesion (18% of total cases). Out of the total 400 cases, 261 were males (65.25%). On univariate analysis, paternal age (odds ratio, OR, 2.01), bad obstetric history (OR, 2.65), antenatal febrile illness (OR, 4.12), and advanced maternal age (OR, 3.28) were found to increase the risk of CHD whereas intake of multivitamin (OR, 3.02) was found to be protective. The risk factors were further analyzed with multivariate logistic regression analysis and all the above factors were found to be significantly associated. Conclusion: We noted that the profile of CHD in our population was similar

  5. Congenital defects of the central nervous system and occupational factors during pregnancy. A case-referent study

    SciTech Connect

    Holmberg, P.C.; Nurminen, M.

    1980-01-01

    The possible impact of occupational factors on the furtherance of congenital defects has been under study at our department for the past four years, and it has assumed a special interest because of the importance to understand the etiology of these disorders and a good possibility for prevention by elimination of the causative factor from the work environment. In connection with a register based case-referent study utilizing supplementary information, acquired by a single interviewer, we analyzed various occupational factors related to pregnancy. We found that organic solvent exposure and exposure to various dusts during the pregnant period were more common among the case mothers than among their matched referents. These findings may offer further rough guidance in the quest for the identification of possibly embryotoxic agents that may occur in occupational life.

  6. [Prevalence of dentition defects among pre-school children of Tver region according to epidemiological study].

    PubMed

    Beliaev, V V; Bobrov, D V; Chumakov, A N; Al'-Zrir, O; El'-Aĭdi, M A

    2015-01-01

    Epidemiological dental study of 724 pre-school children in Tver region revealed high prevalence of dentition defects due to premature removal of temporary molars. Dependence of pediatric population need for prosthetic dentistry from regional dental care system staff competence is shown. The date proved the need for standard correction of orthodontists number and broad application of pediatric prosthetics in daily practice.

  7. Studies of oxygen-related and carbon-related defects in high-efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Corbett, J. W.

    1985-01-01

    Oxygen and carbon related defects in silicon, particularly as related to high-efficiency silicon solar cells were studied. A summary of oxygen processes in silicon versus process temperature was shown along with experimental results. The anamolous diffusion of oxygen was explained by the dissociation of the center allowing O sub i to move through the lattices.

  8. RELATIONAHIP BETWEEN AMBIENT AIR QUALITY AND SELECTED BIRTH DEFECTS, SEVEN COUNTY STUDY, TEXAS, 1997-2000

    EPA Science Inventory

    A population-based case-control study investigated the association between maternal exposure to criteria air pollutants, CO, NO2, O3, SO2, and PM10 during weeks three through eight of pregnancy, and the risk of selected cardiac birth defects and oral clefts among live births and ...

  9. COMPARISON OF GEOCODING METHODS USED IN CASE-CONTROL STUDY OF AIR QUALITY AND BIRTH DEFECTS

    EPA Science Inventory

    Introduction: Accurate geocoding of maternal residence is critical to the success of an ongoing case-control study of exposure to five criteria air pollutants and the risk of selected birth defects in seven Texas counties between 1997 and 2000. The geocoded maternal residence a...

  10. RELATIONAHIP BETWEEN AMBIENT AIR QUALITY AND SELECTED BIRTH DEFECTS, SEVEN COUNTY STUDY, TEXAS, 1997-2000

    EPA Science Inventory

    A population-based case-control study investigated the association between maternal exposure to criteria air pollutants, CO, NO2, O3, SO2, and PM10 during weeks three through eight of pregnancy, and the risk of selected cardiac birth defects and oral clefts among live births and ...

  11. COMPARISON OF GEOCODING METHODS USED IN CASE-CONTROL STUDY OF AIR QUALITY AND BIRTH DEFECTS

    EPA Science Inventory

    Introduction: Accurate geocoding of maternal residence is critical to the success of an ongoing case-control study of exposure to five criteria air pollutants and the risk of selected birth defects in seven Texas counties between 1997 and 2000. The geocoded maternal residence a...

  12. Acquired Color Vision Defects and Hexane Exposure: A Study of San Francisco Bay Area Automotive Mechanics.

    PubMed

    Beckman, Stella; Eisen, Ellen A; Bates, Michael N; Liu, Sa; Haegerstrom-Portnoy, Gunilla; Hammond, S Katharine

    2016-06-01

    Occupational exposure to solvents, including n-hexane, has been associated with acquired color vision defects. Blue-yellow defects are most common and may be due to neurotoxicity or retinal damage. Acetone may potentiate the neurotoxicity of n-hexane. We present results on nonhexane solvent and hexane exposure and color vision from a cross-sectional study of 835 automotive repair workers in the San Francisco Bay Area, California (2007-2013). Cumulative exposure was estimated from self-reported work history, and color vision was assessed using the Lanthony desaturated D-15 panel test. Log-binomial regression was used to estimate prevalence ratios for color vision defects. Acquired color vision defects were present in 29% of participants, of which 70% were blue-yellow. Elevated prevalence ratios were found for nonhexane solvent exposure, with a maximum of 1.31 (95% confidence interval (CI): 0.86, 2.00) for blue-yellow. Among participants aged ≤50 years, the prevalence ratio for blue-yellow defects was 2.17 (95% CI: 1.03, 4.56) in the highest quartile of nonhexane solvent exposure and 1.62 (95% CI: 0.97, 2.72) in the highest category of exposure to hexane with acetone coexposure. Cumulative exposures to hexane and nonhexane solvents in the highest exposure categories were associated with elevated prevalence ratios for color vision defects in younger participants. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Epigenetic profiles in children with a neural tube defect; a case-control study in two populations.

    PubMed

    Stolk, Lisette; Bouwland-Both, Marieke I; van Mil, Nina H; van Mill, Nina H; Verbiest, Michael M P J; Eilers, Paul H C; Zhu, Huiping; Suarez, Lucina; Uitterlinden, André G; Steegers-Theunissen, Régine P M

    2013-01-01

    Folate deficiency is implicated in the causation of neural tube defects (NTDs). The preventive effect of periconceptional folic acid supplement use is partially explained by the treatment of a deranged folate-dependent one carbon metabolism, which provides methyl groups for DNA-methylation as an epigenetic mechanism. Here, we hypothesize that variations in DNA-methylation of genes implicated in the development of NTDs and embryonic growth are part of the underlying mechanism. In 48 children with a neural tube defect and 62 controls from a Dutch case-control study and 34 children with a neural tube defect and 78 controls from a Texan case-control study, we measured the DNA-methylation levels of imprinted candidate genes (IGF2-DMR, H19, KCNQ1OT1) and non-imprinted genes (the LEKR/CCNL gene region associated with birth weight, and MTHFR and VANGL1 associated with NTD). We used the MassARRAY EpiTYPER assay from Sequenom for the assessment of DNA-methylation. Linear mixed model analysis was used to estimate associations between DNA-methylation levels of the genes and a neural tube defect. In the Dutch study group, but not in the Texan study group we found a significant association between the risk of having an NTD and DNA methylation levels of MTHFR (absolute decrease in methylation of -0.33% in cases, P-value = 0.001), and LEKR/CCNL (absolute increase in methylation: 1.36% in cases, P-value = 0.048), and a borderline significant association for VANGL (absolute increase in methylation: 0.17% in cases, P-value = 0.063). Only the association between MTHFR and NTD-risk remained significant after multiple testing correction. The associations in the Dutch study were not replicated in the Texan study. We conclude that the associations between NTDs and the methylation of the MTHFR gene, and maybe VANGL and LEKKR/CNNL, are in line with previous studies showing polymorphisms in the same genes in association with NTDs and embryonic development, respectively.

  14. In Situ Studies on Twin-Thickness-Dependent Distribution of Defect Clusters in Heavy Ion-Irradiated Nanotwinned Ag

    NASA Astrophysics Data System (ADS)

    Li, Jin; Chen, Y.; Wang, H.; Zhang, X.

    2017-03-01

    Recent studies have shown that twin boundaries are effective defect sinks in heavy ion irradiated nanotwinned (nt) metals. Prior in situ radiation studies on nt Ag at room temperature indicate that the accumulative defect concentration is higher in center areas in the 60-nm-thick twins, and twin boundaries are distorted and self-heal during the absorption of different types of defect clusters. In this follow-up study, we show that the spatial distribution of accumulative defect concentrations in nt metals has a clear dependence on twin thickness, and in certain cases, the trend of spatial distribution is reversed. Potential mechanisms for the counterintuitive findings are discussed.

  15. In Situ Studies on Twin-Thickness-Dependent Distribution of Defect Clusters in Heavy Ion-Irradiated Nanotwinned Ag

    NASA Astrophysics Data System (ADS)

    Li, Jin; Chen, Y.; Wang, H.; Zhang, X.

    2017-01-01

    Recent studies have shown that twin boundaries are effective defect sinks in heavy ion irradiated nanotwinned (nt) metals. Prior in situ radiation studies on nt Ag at room temperature indicate that the accumulative defect concentration is higher in center areas in the 60-nm-thick twins, and twin boundaries are distorted and self-heal during the absorption of different types of defect clusters. In this follow-up study, we show that the spatial distribution of accumulative defect concentrations in nt metals has a clear dependence on twin thickness, and in certain cases, the trend of spatial distribution is reversed. Potential mechanisms for the counterintuitive findings are discussed.

  16. Basic Study on Term of Warranty Liability for Water Supply, Drainage, and Sanitation Arrangement Work Defect in Apartment Building

    NASA Astrophysics Data System (ADS)

    Park, Junmo; Seo, DeokSeok

    2017-06-01

    The defect lawsuit of the apartment which is the representative residential style of Korea continues and becomes a social problem. In the defect lawsuit, the term of warranty liability is a period that can demand the defect repair according to defect occurrence, and the exclusion period of the exercise of rights. However, the term of warranty liability stipulated in relevant laws such as Enforcement Decree of the Housing Act is being changed arbitrarily, without any established grounds. Therefore, a reasonable standard for establishing the term of warranty liability is required. In this study, the defects of water supply, drainage and sanitation arrangement work were studied. As a result of analyzing the number of defect occurrence in the apartment, it was shown that the defects in water supply, drainage and sanitation arrangement work occurred more than 80% in the 1st ∼ 2nd year after completion. However, the occurrence of defects from the 3rd year was extremely slight. On the other hand, it was confirmed that the defect occurrence continued until fairly late point of time as the end point of time of the defects was in the 7th to 9th years.

  17. Maternal and infant genetic variants, maternal periconceptional use of selective serotonin reuptake inhibitors, and risk of congenital heart defects in offspring: population based study.

    PubMed

    Nembhard, Wendy N; Tang, Xinyu; Hu, Zhuopei; MacLeod, Stewart; Stowe, Zachary; Webber, Daniel

    2017-03-06

    Objective To evaluate whether the association between maternal periconceptional use of selective serotonin reuptake inhibitors (SSRIs) and increased risk of congenital heart defects in offspring is modified by maternal or infant genetic variants in folate, homocysteine, or transsulfuration pathways.Design Population based study. DNA from mothers, fathers, and infants was genotyped with an Illumina GoldenGate custom single nucleotide polymorphism panel. A hybrid design based on a log linear model was used to calculate relative risks and Bayesian false discovery probabilities (BFDP) to identify polymorphisms associated with congenital heart defects modified by SSRI use.Data sources Data from the US National Birth Defects Prevention Study on 1180 liveborn infants with congenital heart defects and 1644 controls, born 1997-2008.Main outcome measures Cases included infants with selected congenital heart defects and control infants had no major defects. SSRI use was obtained from telephone interviews with mothers.Results For women who reported taking SSRIs periconceptionally, maternal SHMT1 (rs9909104) GG and AGgenotypes were associated with a 5.9 and 2.4 increased risk of select congenital heart defects in offspring, respectively, versus the AA genotype (BFDP=0.69). Compared with the AA genotype, BHMT (rs492842 and rs542852) GG and AG genotypes were associated with twice the riskof congenital heart defects (BFDP=0.74 and 0.79, respectively). MGST1 (rs2075237) CC and ACgenotypes were associated with an increased risk compared with the GG genotype (8.0 and 2.8, respectively; BFDP=0.79). Single nucleotide polymorphism in infant genes in the folate (MTHFS rs12438477), homocysteine (TRDMT1 rs6602178 and GNMT rs11752813) and transsulfuration (GSTP1 rs7941395 and MGST1 rs7294985) pathways were also associated with an increased risk of congenital heart defects.Conclusions Common maternal or infant genetic variants in folate, homocysteine, or transsulfuration pathways are

  18. Experimental study of point-defect creation in high-energy heavy-ion tracks

    NASA Astrophysics Data System (ADS)

    Perez, A.; Balanzat, E.; Dural, J.

    1990-03-01

    Thin platelets of LiF crystals have been bombarded on the side with Ne (40 MeV/amu), Ar (60 MeV/amu), Kr (42 MeV/amu), and Xe (27 MeV/amu) ions at room temperature in the dose range from 108 to 1013 ions cm-2. Taking into account the large penetration depths of these high-energy ions (~=1.4, 1.8, 0.6, and 0.2 mm for Ne, Ar, Kr, and Xe, respectively), it was possible to measure the depth distribution profiles of primary point defects (F centers) and aggregated defects (F2 centers) using a microspectrophotometric technique. These defects are localized in tracks surrounding the ion trajectories in which the energy is deposited by the δ rays emitted. Concerning the creation of primary defects, it has been shown that each individual track is saturated with F centers (~=4×1018 F centers/cm3). From the evolution of the F center depth profiles as a function of the ion doses, using a model of saturated tracks, it has been possible to determine the radii of the tracks all along the ion trajectories. These radii, which are of the order of 7.5, 8, 14, and 32 nm at the entrance in the crystals for Ne, Ar, Kr, and Xe, respectively, increase continuously up to the values of 12, 16, 20, and 44 nm during the slowing down of the ions up to the end of the trajectories. In the wide range of energy deposition into electronic processes studied (from 0.2 to 20 MeV μm-1), a continuous behavior of the primary-defect creation is observed. This seems to indicate that the same excitonic mechanism is responsible of the primary-Frenkel-pair creation in the volume of the track irradiated by the secondary electrons and other mechanisms such as Coulomb explosion or melting, which could take place in the tracks above a certain dissipated-energy threshold, must be ruled out. Finally, the specificity of damaging with ions compared with other irradiation modes (electrons or electromagnetic radiation) is mainly observed with aggregated defects. Due to the high energy density dissipated in the tracks

  19. Bar Study Stories. Issues in Prevention

    ERIC Educational Resources Information Center

    Higher Education Center for Alcohol, Drug Abuse, and Violence Prevention, 2012

    2012-01-01

    This issue of "Issues in Prevention" focuses on the impact of the availability of drinks in licensed establishments, such as bars and taverns on student drinking. This issue contains the following articles: (1) Cheap Drinks at College Bars Can Escalate Student Drinking (John D. Clapp); (2) High Alcohol Outlet Density: A Problem for Campuses and…

  20. Delayed primary closure of contaminated abdominal wall defects with non-crosslinked porcine acellular dermal matrix compared with conventional staged repair: a retrospective study

    PubMed Central

    2014-01-01

    Introduction Synthetic mesh has been used traditionally to repair abdominal wall defects, but its use is limited in the case of bacterial contamination. New biological materials are now being used successfully for delayed primary closure of contaminated abdominal wall defects. The costs of biological materials may prevent surgeons from using them. We compared the conventional staged repair of contaminated abdominal wall defects with a single-stage procedure using a non-crosslinked porcine acellular dermal matrix. Methods A total of 14 cases with Grade 3 contaminated abdominal wall defects underwent delayed primary closure of the abdomen using a non-crosslinked porcine acellular dermal matrix (Strattice™ Reconstructive Tissue Matrix, LifeCell Corp., Branchburg, NJ, USA). The results were compared with a group of 14 patients who had received conventional treatment for the repair of contaminated abdominal wall defects comprising a staged repair during two separate hospital admissions employing synthetic mesh. Treatment modalities, outcomes, and costs were compared. Results In all cases treated with delayed primary closure employing non-crosslinked porcine acellular dermal matrix, there were no complications related to its use. Two patients died due to unrelated events. Although treatment costs were estimated to be similar in the two groups, the patients treated with porcine acellular dermal matrix spent less time as an inpatient than those receiving conventional two-stage repair. Conclusions Delayed primary closure of contaminated abdominal wall defects using a non-crosslinked porcine acellular dermal matrix may be a suitable alternative to conventional staged repair. In our patients, it resulted in early restoration of abdominal wall function and shorter hospitalization. The costs for treating contaminated abdominal wall defects using porcine acellular dermal matrix during a single hospital admission were not higher than costs for conventional two-stage repair

  1. Grain boundary defects initiation at the outer surface of dissimilar welds: Corrosion mechanism studies

    SciTech Connect

    Bouvier, O. De; Yrieix, B.

    1995-12-31

    Dissimilar welds located on the primary coolant system of the French PWR plants exhibit grain boundary defects in the true austenitic zones of the first buttering layer. If grain boundaries reach the interface, they can extend to the martensitic band. Those defects are filled with compact oxides. In addition, the ferritic base metal presents some pits along the interface. Nowadays, three mechanisms are proposed to explain the initiation of those defects: stress corrosion cracking, intergranular corrosion and high temperature intergranular oxidation. This paper is dealing with the study of the mechanisms involved in the corrosion phenomenon. Intergranular corrosion tests performed on different materials show that only the first buttering layer, even with some {delta} ferrite, is sensitized. The results of stress corrosion cracking tests in water solutions show that intergranular cracking is possible on a bulk material representative of the first buttering layer. It is unlikely on actual dissimilar welds where the ferritic base metal protects the first austenitic layer by galvanic coupling. Therefore, the stress corrosion cracking assumption cannot explain the initiation of the defects in aqueous environment. The results of the investigations and of the corrosion studies led to the conclusion that the atmosphere could be the only possible aggressive environment. This conclusion is based on natural atmospheric exposure and accelerated corrosion tests carried out with SO{sub 2} additions in controlled atmosphere. They both induce a severe intergranular corrosion on true sensitized austenitic materials.

  2. A study of handling cytotoxic drugs and risk of birth defects in offspring of female veterinarians.

    PubMed

    Shirangi, Adeleh; Bower, Carol; Holman, C D'Arcy J; Preen, David B; Bruce, Neville

    2014-06-12

    We examined the association of occupational exposure to handling cytotoxic drugs at work with risk of birth defects among a cohort of female veterinarians. This study is a follow up survey of 321 female participants (633 pregnancies) who participated in the Health Risks of Australian Veterinarian project. Data on pregnancies and exposure during each pregnancy was obtained by self-administered mailed questionnaire. Female veterinarians handling cytotoxic drugs during their pregnancy had a two-fold increased risk of birth defects in their offspring (RR = 2.08, 95% CI (1.05-4.15)). Results were consistent in subgroup analysis of those who graduated during the period of 1961 to 1980 (RR = 5.04, 95% CI (1.81, 14.03) and in those working specifically in small and large animal practice. There was no increased risk in the subgroup that graduated after 1980. Women with unplanned pregnancies were more likely to handle cytotoxic drugs on a daily basis (RR = 1.86, 95% CI, 1.00-3.48) and had a higher increased risk of birth defects than those who planned their pregnancies in recent graduates and in those who worked specifically in small animal practice (RR = 2.53, 95% CI, 1.18-5.42). This study suggests that the adverse effects of handling cytotoxic drugs in pregnant women may include an increased risk of birth defects. Pregnancy intention status is an important health behavior and should be considered in prenatal programs.

  3. Bare dorsal thoracic fascial flap for esophageal defects: an experimental study with dogs.

    PubMed

    Ugurlu, Kemal; Karsidag, Tamer; Huthut, Ilkay; Karsidag, Semra; Ozer, Kursat; Sacak, Bulent; Akcal, Arzu

    2012-06-01

    Reconstruction of esophageal defects has challenged reconstructive surgeons for a long time. Problems that affect the continuity of the orogastic tract influence the patient's quality of life and general health. Bare free fascial flaps are used to restore soft tissue defects of the oral cavity because they provide thin, pliable tissues with a high capacity for epithelialization to preserve the local anatomy. An experimental study was planned to investigate reconstruction of anterior cervical esophageal defects using a pedicled dorsal thoracic fascial flap. Eight hybrid dogs were used in the study. All operations were planned in three steps and performed with the animals under general anesthesia. For the two-layered reconstruction, the bare dorsal thoracic fascial flap was harvested and adapted like a patch to the defect. No partial or total flap loss was observed. On postoperative day 20 surgery, a complete epithelial lining on the same plane as the esophageal mucosa was observed over the flap tissue. A 4- to 5-mm longitudinal scar that did not form even a minimal stricture in any dog also was observed. No significant changes from postoperative day 20 to postoperative days 40 and 60 were observed. Bare fascial flaps in the oral cavity heal with spontaneous epithelialization and with no need for skin and mucosal grafts. Fascial flaps are easy to harvest and do not cause any functional loss because they are nonfunctional units. Their thin constitution helps the surgeon to shape the tissue and even form tubed flaps.

  4. A codon-shuffling method to prevent reversion during production of replication-defective herpesvirus stocks: Implications for herpesvirus vaccines.

    PubMed

    Li, Gang; Ward, Charles; Yeasmin, Rukhsana; Skiena, Steven; Krug, Laurie T; Forrest, J Craig

    2017-03-13

    Herpesviruses establish life-long chronic infections that place infected hosts at risk for severe disease. Herpesvirus genomes readily undergo homologous recombination (HR) during productive replication, often leading to wild-type (WT) reversion during complementation of replication-defective and attenuated viruses via HR with the helper gene provided in trans. To overcome this barrier, we developed a synthetic-biology approach based on a technique known as codon shuffling. Computer-assisted algorithms redistribute codons in a helper gene, thereby eliminating regions of homology, while enabling manipulation of factors such as codon-pair bias and CpG content to effectively titrate helper-gene protein levels. We apply this technique to rescue the replication of a murine gammaherpesvirus engineered with a mutation in the major immediate-early transactivator protein RTA. Complementation with codon-shuffled RTA constructs did not yield any WT revertant virus, a sharp contrast to WT virus contamination frequently observed during complementation with an unmodified helper gene. We further demonstrate the importance of eliminating WT virus contamination in an animal model of gammaherpesvirus lethality. We propose complementation by codon shuffling as a means to produce replication-defective or attenuated viruses. This method has immediate utility for investigating roles of essential genes in viral replication and will better enable future development of herpesvirus vaccines.

  5. A codon-shuffling method to prevent reversion during production of replication-defective herpesvirus stocks: Implications for herpesvirus vaccines

    PubMed Central

    Li, Gang; Ward, Charles; Yeasmin, Rukhsana; Skiena, Steven; Krug, Laurie T.; Forrest, J. Craig

    2017-01-01

    Herpesviruses establish life-long chronic infections that place infected hosts at risk for severe disease. Herpesvirus genomes readily undergo homologous recombination (HR) during productive replication, often leading to wild-type (WT) reversion during complementation of replication-defective and attenuated viruses via HR with the helper gene provided in trans. To overcome this barrier, we developed a synthetic-biology approach based on a technique known as codon shuffling. Computer-assisted algorithms redistribute codons in a helper gene, thereby eliminating regions of homology, while enabling manipulation of factors such as codon-pair bias and CpG content to effectively titrate helper-gene protein levels. We apply this technique to rescue the replication of a murine gammaherpesvirus engineered with a mutation in the major immediate-early transactivator protein RTA. Complementation with codon-shuffled RTA constructs did not yield any WT revertant virus, a sharp contrast to WT virus contamination frequently observed during complementation with an unmodified helper gene. We further demonstrate the importance of eliminating WT virus contamination in an animal model of gammaherpesvirus lethality. We propose complementation by codon shuffling as a means to produce replication-defective or attenuated viruses. This method has immediate utility for investigating roles of essential genes in viral replication and will better enable future development of herpesvirus vaccines. PMID:28287622

  6. Elucidation of phenomena in high-power fiber laser welding and development of prevention procedures of welding defects

    NASA Astrophysics Data System (ADS)

    Katayama, Seiji; Kawahito, Yousuke

    2009-02-01

    Fiber lasers have been receiving considerable attention because of their advantages of high power, high beam quality and high efficiency, and are expected as one of the desirable heat sources for high-speed and deep-penetration welding. In our researches, therefore, the effects of laser powers and their densities on the weld penetration and the formation of sound welds were investigated in welding of Type 304 austenitic stainless steel, A5052 aluminum alloy or high strength steel plates with four laser beams of about 0.12 to 1 mm in focused spot diameter, and their welding phenomena were observed with high-speed video cameras and X-ray transmission real-time imaging system. It was found that the laser power density exerted a remarkable effect on the increase in weld penetration at higher welding speeds, but on the other hand at low welding speeds deeper-penetration welds could be produced at higher power. Laser-induced plume behavior and its effect on weld penetration, and the mechanisms of spattering, underfilling, porosity and humping were elucidated, sound welds without welding defects could be produced under the improved welding conditions. In addition, importance of the development of focusing optics and the removal of a plume during remote welding will be emphasized in terms of the stable production of constant deep-penetration welds and the reduction in welding defects in high power laser welding.

  7. Some studies to prevent the production of some types of moire effects in fabrics

    NASA Astrophysics Data System (ADS)

    Serrano, Alfonso; Ponce, Rodrigo; Serroukh, Ibrahim

    2004-09-01

    The symmetry concerning the fabric pattern is not always suitable for the quality that we expected from fabric textile. The moire effects produced by a periodic structure may be caused by various and diverse factors as folds, lines, etc. The defect that we are concern is bright and dark fringes appearing in the Nylon Fabric are viewed with necked eye, from a particular angle using white light. To prevent these annoying effects, one should be focusing the research basically on geometrical fabric structure, physical, optical and dyeing. We start this work by an exhaustive study made to obtain enough information in order to identify and analyze the problem in order to identify, explain and prevent it appearance. To realize that we may define the factors that causes the phenomena. Concerning the experimental results, we begin with a conventional experiment called "Flat table examination" using Fluorescent white light bulb as types of illumination. We have used as well a microscope examination. It is useful to inspect the fiber and yarns which may have different characteristics of size and form. The light interaction with the fiber will produce especially kind of reflection and absorption. We finish the work by designing and developing an optical system able not only for detecting those kinds of fringes. As well to allow some defects inspection. We believe that some measurements are necessary during some process of fabrication (dyeing, spinning and knitting), at least to reduce this types of defects.

  8. TEM study on the effects of intermediate quenching on some defects in high Jc Bi-2223 tapes

    NASA Astrophysics Data System (ADS)

    Yao, P.; Zeng, R.; Liu, H. K.; Dou, S. X.

    2000-07-01

    The microstructure of the 69-filamentary Bi-2223 tapes with high Jc of 51 000 A/cm 2 at 77 K and self-field has been studied by using the transmission electron microscopy (TEM) method. The tapes were treated by two steps sintering with intermediate quenching (IQ) and pressing [S.X. Dou, R. Zeng, T.P. Beals, H.K. Liu, Physica C 303 (1998) 21]. The diversified defects in the grains or colonies that influence the properties of the tapes were thoroughly observed by TEM. IQ is an effective method to promote the healing of the cracks, prevent the forming of the large secondary phases, and affects the critical current density of the tapes.

  9. Association between Prenatal Exposure to Antiretroviral Therapy and Birth Defects: An Analysis of the French Perinatal Cohort Study (ANRS CO1/CO11)

    PubMed Central

    Sibiude, Jeanne; Mandelbrot, Laurent; Blanche, Stéphane; Le Chenadec, Jérôme; Boullag-Bonnet, Naima; Faye, Albert; Dollfus, Catherine; Tubiana, Roland; Bonnet, Damien; Lelong, Nathalie; Khoshnood, Babak; Warszawski, Josiane

    2014-01-01

    Background Antiretroviral therapy (ART) has major benefits during pregnancy, both for maternal health and to prevent mother-to-child transmission of HIV. Safety issues, including teratogenic risk, need to be evaluated. We estimated the prevalence of birth defects in children born to HIV-infected women receiving ART during pregnancy, and assessed the independent association of birth defects with each antiretroviral (ARV) drug used. Methods and Findings The French Perinatal Cohort prospectively enrolls HIV-infected women delivering in 90 centers throughout France. Children are followed by pediatricians until 2 y of age according to national guidelines. We included 13,124 live births between 1994 and 2010, among which, 42% (n = 5,388) were exposed to ART in the first trimester of pregnancy. Birth defects were studied using both European Surveillance of Congenital Anomalies (EUROCAT) and Metropolitan Atlanta Congenital Defects Program (MACDP) classifications; associations with ART were evaluated using univariate and multivariate logistic regressions. Correction for multiple comparisons was not performed because the analyses were based on hypotheses emanating from previous findings in the literature and the robustness of the findings of the current study. The prevalence of birth defects was 4.4% (95% CI 4.0%–4.7%), according to the EUROCAT classification. In multivariate analysis adjusting for other ARV drugs, maternal age, geographical origin, intravenous drug use, and type of maternity center, a significant association was found between exposure to zidovudine in the first trimester and congenital heart defects: 2.3% (74/3,267), adjusted odds ratio (AOR) = 2.2 (95% CI 1.3–3.7), p = 0.003, absolute risk difference attributed to zidovudine +1.2% (95% CI +0.5; +1.9%). Didanosine and indinavir were associated with head and neck defects, respectively: 0.5%, AOR = 3.4 (95% CI 1.1–10.4), p = 0.04; 0.9%, AOR = 3.8 (95% CI 1.1–13.8), p = 0

  10. New nano-hydroxyapatite in bone defect regeneration: A histological study in rats.

    PubMed

    Kubasiewicz-Ross, Paweł; Hadzik, Jakub; Seeliger, Julia; Kozak, Karol; Jurczyszyn, Kamil; Gerber, Hanna; Dominiak, Marzena; Kunert-Keil, Christiane

    2017-09-01

    Many types of bone substitute materials are available on the market. Researchers are refining new bone substitutes to make them comparable to autologous grafting materials in treatment of bone defects. The purpose of the study was to evaluate the osseoconductive potential and bone defect regeneration in rat calvaria bone defects treated with new synthetic nano-hydroxyapatite. The study was performed on 30 rats divided into 5 equal groups. New preproduction of experimental nano-hydroxyapatite material by NanoSynHap (Poznań, Poland) was tested and compared with commercially available materials. Five mm critical size defects were created and filled with the following bone grafting materials: 1) Geistlich Bio-Oss(®); 2) nano-hydroxyapatite+β-TCP; 3) nano-hydroxyapatite; 4) nano-hydroxyapatite+collagen membrane. The last group served as controls without any augmentation. Bone samples from calvaria were harvested for histological and micro-ct evaluation after 8 weeks. New bone formation was observed in all groups. Histomorphometric analysis revealed an amount of regenerated bone between 34.2 and 44.4% in treated bone defects, whereas only 13.0% regenerated bone was found in controls. Interestingly, in group 3, no significant particles of the nano-HA material were found. In contrast, residual bone substitute material could be detected in all other test groups. Micro-CT study confirmed the results of the histological examinations. The new nano-hydroxyapatite provides comparable results to other grafts in the field of bone regeneration. Copyright © 2017 Elsevier GmbH. All rights reserved.

  11. Effect of dolomite on the repair of bone defects in rats: histological study.

    PubMed

    Moreschi, Eduardo; Hernandes, Luzmarina; Dantas, Jailson Araujo; da Silva, Maria Angélica Raffaini Covas Pereira; Casaroto, Ana Regina; Bersani-Amado, Ciomar Aparecida

    2010-12-01

    The aim of the present study was to evaluate histologically and radiographically the tissue response to dolomite [CaMg(CO3)2] and its osteogenic potential in the repair of bone cavities in the calvaria of rats. A bone defect 10 mm in diameter and 1 mm deep was made in the calvaria of male Wistar rats. The defects were filled with dolomite, inorganic bovine bone (positive control), or coagulum (negative control). The animals were euthanized 7, 15, 30, and 60 days after surgery, and specimens were collected for radiographic and microscopic analyses. The bone defects were processed for paraffin embedding and H&E staining. The histological study revealed that dolomite stimulated a moderate inflammatory response, with programmed cell death in the first 15 days, compared to bovine bone which showed a moderate to intense acute response. In the chronic phase, the inflammatory response was characterized by the occurrence of macrophages organized as epithelioid cells in the dolomite group, and giant cells in the bovine-bone group. Fibrosis developed in all three groups; however, encapsulation of the fragments, reabsorption, and osteoconductive activity occurred only in the defects filled with bovine bone. The radiographic analysis showed that the bovine bone was most efficient in the repair of the defects, followed by the dolomite and the coagulum. This study demonstrated that the dolomite stimulated a moderate acute inflammatory response with programmed cell death, and a chronic inflammatory response by means of the phagocytic mononuclear system. Although osteo-conductive activity was not shown, the dolomite favored the repair process, compared to the coagulum group.

  12. Prevention

    MedlinePlus

    ... Error processing SSI file About Heart Disease & Stroke Prevention Heart disease and stroke are an epidemic in ... secondhand smoke. Barriers to Effective Heart Disease & Stroke Prevention Many people with key risk factors for heart ...

  13. The contribution of chromosomal abnormalities to congenital heart defects: a population-based study.

    PubMed

    Hartman, Robert J; Rasmussen, Sonja A; Botto, Lorenzo D; Riehle-Colarusso, Tiffany; Martin, Christa L; Cragan, Janet D; Shin, Mikyong; Correa, Adolfo

    2011-12-01

    We aimed to assess the frequency of chromosomal abnormalities among infants with congenital heart defects (CHDs) in an analysis of population-based surveillance data. We reviewed data from the Metropolitan Atlanta Congenital Defects Program, a population-based birth-defects surveillance system, to assess the frequency of chromosomal abnormalities among live-born infants and fetal deaths with CHDs delivered from January 1, 1994, to December 31, 2005. Among 4430 infants with CHDs, 547 (12.3%) had a chromosomal abnormality. CHDs most likely to be associated with a chromosomal abnormality were interrupted aortic arch (type B and not otherwise specified; 69.2%), atrioventricular septal defect (67.2%), and double-outlet right ventricle (33.3%). The most common chromosomal abnormalities observed were trisomy 21 (52.8%), trisomy 18 (12.8%), 22q11.2 deletion (12.2%), and trisomy 13 (5.7%). In conclusion, in our study, approximately 1 in 8 infants with a CHD had a chromosomal abnormality. Clinicians should have a low threshold at which to obtain testing for chromosomal abnormalities in infants with CHDs, especially those with certain types of CHDs. Use of new technologies that have become recently available (e.g., chromosomal microarray) may increase the identified contribution of chromosomal abnormalities even further.

  14. A molecular dynamics simulation study of irradiation induced defects in gold nanowire

    NASA Astrophysics Data System (ADS)

    Liu, Wenqiang; Chen, Piheng; Qiu, Ruizhi; Khan, Maaz; Liu, Jie; Hou, Mingdong; Duan, Jinglai

    2017-08-01

    Displacement cascade in gold nanowires was studied using molecular dynamics computer simulations. Primary knock-on atoms (PKAs) with different kinetic energies were initiated either at the surface or at the center of the nanowires. We found three kinds of defects that were induced by the cascade, including point defects, stacking faults and crater at the surface. The starting points of PKAs influence the number of residual point defects, and this consequently affect the boundary of anti-radiation window which was proposed by calculation of diffusion of point defects to the free surface of nanowires. Formation of stacking faults that expanded the whole cross-section of gold nanowires was observed when the PKA's kinetic energy was higher than 5 keV. Increasing the PKA's kinetic energy up to more than 10 keV may lead to the formation of crater at the surface of nanowires due to microexplosion of hot atoms. At this energy, PKAs started from the center of nanowires can also result in the creation of crater because length of cascade region is comparable to diameter of nanowires. Both the two factors, namely initial positions of PKAs as well as the craters induced by higher energy irradiation, would influence the ability of radiation resistance of metal nanowires.

  15. Native Point Defects in GaN: A Hybrid-Functional Study

    NASA Astrophysics Data System (ADS)

    Diallo, I. C.; Demchenko, D. O.

    2016-12-01

    We present a systematic study of properties of common native point defects in GaN based on hybrid density-functional calculations. These defects include vacancies, interstitials, antisites, and common complexes. Using configuration coordinate diagrams, we estimate the likelihood of defects to be radiative or nonradiative. Our results show that gallium vacancies exhibit a large magnetic moment in the neutral charge state and are most likely nonradiative. This is in contrast to nitrogen vacancies, which are probable sources of the experimentally observed green-luminescence band peaking at 2.35 eV in undoped GaN. We also show that infrared photoluminescence (PL) bands that are created by 2.5-MeV electron irradiation in GaN can be explained by the formation of native defects. Namely, the interstitial gallium is likely to be responsible for the narrow infrared PL band centered around 0.85 eV, with a phonon fine structure at 0.88 eV; the gallium-nitrogen divacancies are possible sources of the broad PL band with a peak at 0.95 eV.

  16. Electron spin resonance study of point defects in thermal GaAs/GaAs-oxide structures

    NASA Astrophysics Data System (ADS)

    Nguyen, S.; Afanas'ev, V. V.; Stesmans, A.

    2012-12-01

    In an attempt to atomically assess interface and oxide-related point defects, a first basic multifrequency low-temperature electron spin resonance study has been carried out on semi-insulating (Fe compensated) GaAs/oxide structures, implying both powders and (100)GaAs/oxide slices, thermally grown in the range Tox=350-615 °C. Various spectra are observed: As for powders, this includes the 4-line EL2 defect spectrum centered at g~2.043 and characterized by the isotropic hyperfine constant Aiso~ 910 G, ascribed to the 75AsGa+ antisite defect. Observed in freshly crushed powder, it substantially increases in density with oxidation, in line with theoretical expectation; A maximum appears reached for at Tox~440 °C. It is not observed in the parent c-GaAs wafer. A second isotropic signal is observed at g~1.937 in powders for Tox in the range 510-615 °C, but only after additional VUV irradiation; it may correspond to As clusters. In bulk (100)GaAs, we observe the 5-branch spectrum of substitutional Fe impurities (spin S=5/2) in GaAs, with inferred crystal field constant a ≈ 360 G, well in line with previous observations. The results are discussed within the framework of advanced theoretical interface and defect models and previous experimental assessment.

  17. Positron annihilation study of defects in electron-irradiated single crystal zinc oxide

    NASA Astrophysics Data System (ADS)

    To, C. K.; Yang, B.; Beling, C. D.; Fung, S.; Ling, C. C.; Gong, M.

    2011-01-01

    Pressurized melt grown zinc oxide (ZnO) single crystals purchased from Cermet Inc. were irradiated by 2MeV electrons with fluence of 6x1017cm-2. Isochronal annealing from 100°C-800°C was performed on the crystals under argon and air ambience. Variable Energy Doppler Broadening Spectroscopy (VEDBS) was carried out on both the as-grown and the irradiated samples at each annealing step. The migration, agglomeration and annealing of grown-in and irradiated-introduced defects were studied. It was observed that the grown-in vacancy-type defects concentration decreased at 300°C and 600 °C. For the irradiated sample annealed in argon, the positron trapping vacancy-type defect concentration decreased at 300°C and 600°C. Further annealing the as-grown and irradiated samples in argon increased the S parameter further. For the irradiated sample annealed in air, the vacancy-type defect concentration decreases at 300°C and 700°C.

  18. Intracytoplasmic morphologically selected sperm injection and congenital birth defects: a retrospective cohort study.

    PubMed

    Hershko-Klement, A; Sukenik-Halevy, R; Biron Shental, T; Miller, N; Berkovitz, A

    2016-09-01

    Our objective was to study the birth defect rates in intracytoplasmic morphologically selected sperm injection (IMSI) pregnancies. A cohort of couples presenting male factor infertility between January 2006 and January 2014 was retrospectively analyzed. Discharge letters and a telephone interview were performed for assessing pregnancy outcome. All clinical data were reviewed by a board certified medical geneticist. Main outcomes were fetal/birth defect and chromosomal abnormality rates. Two thousand two hundred and fifty-eight pregnancies were available for analysis, of them, 1669 (73.9%) resulting from ICSI and 2258 (26.1%) achieved by IMSI. Pregnancy outcome distribution did not show a significant difference. For the fresh embryo transfer cohort, fetal/birth defect rate was 4.5%, chromosomal aberration rate was 1.0%, and structural malformation rate was 3.5%. IMSI vs. ICSI pregnancies were less likely to involve a fetal/birth defect: 3.5% vs. 4.8%, respectively, but did not reach a statistical significance OR 0.71 (95% CI 0.39-1.22). Split by multiplicity, this trend existed only for singleton pregnancies; 1.4% structural malformations rate vs. 3.8%, respectively, OR 0.35 (95% CI 0.11-0.9). The frozen cohort demonstrated a significantly lower birth defect rate (OR 0.25, 95% CI 0.09-0.58). We conclude that IMSI procedure does not involve an increased malformation rate and may offer a reduced anomaly incidence. Further studies are required. © 2016 American Society of Andrology and European Academy of Andrology.

  19. Tri-layered composite plug for the repair of osteochondral defects: in vivo study in sheep

    PubMed Central

    Yucekul, Altug; Ozdil, Deniz; Kutlu, Nuri Hunkar; Erdemli, Esra; Aydin, Halil Murat; Doral, Mahmut Nedim

    2017-01-01

    Cartilage defects are a source of pain, immobility, and reduced quality of life for patients who have acquired these defects through injury, wear, or disease. The avascular nature of cartilage tissue adds to the complexity of cartilage tissue repair or regeneration efforts. The known limitations of using autografts, allografts, or xenografts further add to this complexity. Autologous chondrocyte implantation or matrix-assisted chondrocyte implantation techniques attempt to introduce cultured cartilage cells to defect areas in the patient, but clinical success with these are impeded by the avascularity of cartilage tissue. Biodegradable, synthetic scaffolds capable of supporting local cells and overcoming the issue of poor vascularization would bypass the issues of current cartilage treatment options. In this study, we propose a biodegradable, tri-layered (poly(glycolic acid) mesh/poly(l-lactic acid)-colorant tidemark layer/collagen Type I and ceramic microparticle-coated poly(l-lactic acid)-poly(ϵ-caprolactone) monolith) osteochondral plug indicated for the repair of cartilage defects. The porous plug allows the continual transport of bone marrow constituents from the subchondral layer to the cartilage defect site for a more effective repair of the area. Assessment of the in vivo performance of the implant was conducted in an ovine model (n = 13). In addition to a control group (no implant), one group received the implant alone (Group A), while another group was supplemented with hyaluronic acid (0.8 mL at 10 mg/mL solution; Group B). Analyses performed on specimens from the in vivo study revealed that the implant achieves cartilage formation within 6 months. No adverse tissue reactions or other complications were reported. Our findings indicate that the porous biocompatible implant seems to be a promising treatment option for the cartilage repair. PMID:28694960

  20. MACULAR BRUCH MEMBRANE DEFECTS IN HIGHLY MYOPIC EYES: The Beijing Eye Study.

    PubMed

    You, Qi Sheng; Peng, Xiao Yan; Xu, Liang; Chen, Chang Xi; Wei, Wen Bin; Wang, YaXing; Jonas, Jost B

    2016-03-01

    To examine prevalence and associations of macular Bruch membrane defects (MBMDs) in a population-based setting. Population-based cross-sectional study. The Beijing Eye Study 2011 included 3,468 subjects who underwent a detailed ophthalmic examination including spectral domain optical coherence tomography with enhanced depth imaging of the macula. Macular Bruch membrane defects were defined as an interruption of Bruch membrane on the optical coherence tomography images in the macular region. Macular Bruch membrane defects could be detected only in highly myopic eyes (defined as refractive error of ≤-6 diopters or axial length of ≥26.5 mm) with a prevalence of 17/164 (10.4%, 95% confidence interval [CI], 5.7%-18.1%). Best-corrected visual acuity <0.05 was found in 5 (29%) of 17 eyes with MBMDs, and in 7 (41%) eyes, visual acuity was <0.3 and ≥0.05. In the MBMD region, retinal pigment epithelium and choriocapillaris were completely lost, and the deep and middle layers of the retina and the choroid were almost completely absent. In the MBMD region, mean retinal thickness was 153 ± 57 μm (mean ± SD) and choroidal thickness was 12.7 ± 28.1 μm. On the fundus photographs, MBMDs appeared as whitish areas with round borders. In multivariate regression analysis, presence of MBMD was significantly associated only with longer axial length (Odds ratio: 3.87; 95% CI, 1.64-9.14). Macular Bruch membrane defects with a prevalence of approximately 10% in highly myopic eyes are associated with a complete loss of retinal pigment epithelium and choriocapillaris, an almost complete loss of photoreceptors and choroid, and marked reduction in visual acuity. Macular Bruch membrane defects may be added to the panoply of features of myopic maculopathy.

  1. Exploring the microbiota of the red-brown defect in smear-ripened cheese by 454-pyrosequencing and its prevention using different cleaning systems.

    PubMed

    Guzzon, Raffaele; Carafa, Ilaria; Tuohy, Kieran; Cervantes, Gonzalo; Vernetti, Luca; Barmaz, Andrea; Larcher, Roberto; Franciosi, Elena

    2017-04-01

    Red-brown pigmentation can occasionally form in smeared-ripened cheese such as Fontina during the ripening process. This reaction is due to over-development of the typical microbiota present on the rind. Previous studies have demonstrated the relationship between red-brown pigmentation and the traditional utilization of wooden shelves during cheese ripening. The first part of the paper focuses on the characterisation of yeast and bacterial microbiota: plate counts and 454-pyrosequencing were performed in spoiled (n = 6) and non-spoiled cheeses (n = 6) and on the wooden shelves used during ripening. The second part shows different systems tested for cleaning the wooden shelves and avoiding the development of the red-brown defect in cheese: washing with hot water and ozone treatment. Actinobacteria, dominated on the wooden shelves, suggesting to be responsible for the red-brown pigmentation; they were also found in traces in the defected cheese samples. Galactomyces and Debaryomyces were the main species characterizing the yeast population, with Debaryomyces being the most dominant species on the shelves used during ripening of the red-brown defective cheese. Hot water treatment reduced the microbial contamination of shelves, whereas only the ozone treatment ensured complete elimination of both yeast and bacteria, resulting in the cheese rind not having the red-brown defect.

  2. Light-induced creation of metastable defects in hydrogenated amorphous silicon studied by computer simulations of constant photocurrent measurements

    NASA Astrophysics Data System (ADS)

    Schmidt, J. A.; Arce, R. D.; Koropecki, R. R.; Buitrago, R. H.

    1999-02-01

    The light-induced degradation of an intrinsic hydrogenated amorphous silicon sample has been studied from the evolution of the sub-band-gap absorption coefficient. The experimental results have been modeled using detailed numerical analysis, obtaining the defect distribution within the gap for each illumination time. These results have been compared with those previously obtained from a direct deconvolution of the absorption coefficient spectra [J. A. Schmidt, R. Arce, R. H. Buitrago, and R. R. Koropecki, Phys. Rev. B 55, 9621 (1997)]. We have found, in agreement with our previous work, that (i) the defect density shows the presence of more charged than neutral defects, as predicted by the defect pool model, and (ii) the concentration of charged and neutral defects evolve with the same time dependence, thus contradicting Schumm's generalized model of defect equilibration.

  3. Experimental study on slow flexural waves around the defect modes in a phononic crystal beam using fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Chuang, Kuo-Chih; Zhang, Zhi-Qiang; Wang, Hua-Xin

    2016-12-01

    This work experimentally studies influences of the point defect modes on the group velocity of flexural waves in a phononic crystal Timoshenko beam. Using the transfer matrix method with a supercell technique, the band structures and the group velocities around the defect modes are theoretically obtained. Particularly, to demonstrate the existence of the localized defect modes inside the band gaps, a high-sensitivity fiber Bragg grating sensing system is set up and the displacement transmittance is measured. Slow propagation of flexural waves via defect coupling in the phononic crystal beam is then experimentally demonstrated with Hanning windowed tone burst excitations.

  4. Association of GDF1 rs4808863 with fetal congenital heart defects: a case–control study

    PubMed Central

    Zhang, Juan; Wu, Qingqing; Wang, Li; Li, Xiaofei; Ma, Yuqing; Yao, Ling

    2015-01-01

    Background Congenital heart defects (CHDs) are the most common fetal defects and the most important cause of child mortality and morbidity. Objective To investigate the association between growth/differentiation factor 1 (GDF1) polymorphisms and fetal CHDs, by evaluating the association of GDF1 rs4808863 with fetal CHDs. Design A case–control study. Setting Beijing, China. Participants We selected 124 fetuses with a CHD and a normal karyotype and normal array-based comparative genomic hybridisation analysis and compared them with 124 normal fetuses matched for gestational age and sex. Fetuses with a CHD, from 20 to 32 weeks of gestation were included. Fetuses with any chromosomal abnormalities, and fetuses from multiple pregnancies and those carried by pregnant women with chronic diseases, were excluded from this research. DNA extraction and genotyping were carried out for all cases to investigate the genotype distributions of GDF1 rs4808863. Results A significant difference was noted for the CT phenotype of GDF1 rs4808863 between the controls and the fetuses with CHDs using homozygote and heterozygote comparisons. The minor allele (T allele) of GDF1 rs4808863 was associated with an increased risk of CHD (p<0.05). A statistically significant difference between controls and fetuses with CHDs was noted in a comparison with the mutation genotype CT+TT and wild-type genotype CC (p<0.05) using dominant modal analysis. After stratification analysis, the CT phenotype, the minor allele (T allele) and the mutation genotype CT+TT of the rs4808863 polymorphism were associated with atrioventricular septal defect (AVSD), left ventricular outflow tract obstruction (LVOTO) and left–right laterality defects (p<0.05). Conclusions Our results suggest that the GDF1 rs4808863 polymorphism contributes to an increased risk of fetal CHDs, especially the subtypes of AVSD, LVOTO and left–right laterality defects. PMID:26656983

  5. Stability of tibial defect reconstruction with fibular graft and unilateral external fixation: a finite element study

    PubMed Central

    Chen, Huiqiang; Zhang, Ying; Xia, Hong; Wang, Fei; Li, Zhibo; Chen, Xuxiang

    2014-01-01

    Tibial defect is generally caused by high-energy injury, tumor, osteomyelitis, development deformity and bone non-union after internal fixation. This study was to determine stability of tibial defect reconstruction with fibular graft (FG) of different lengths by single free vascularized fibular graft (SFVFG) and double-barrel free vascularized fibular graft (DBFVFG). The left lower extremity of a male volunteer was scanned with computer tomography scanner. The contours of the tibia and fibula were extracted and the geometry of both bones rebuilt. From this intact model, the models of tibial defect reconstruction with fibular graft and external fixation were developed. Inter-fragmentary motion (IFM) and Von Mises stress on the fibular bone flap, and the locations of maximum Von Mises stress were introduced to quantify the biomechanical environment. Under the condition of the same graft length, the Von Mises stress value in DBFVFG group was 1.37 to 1.77 times higher than that in SFVFG group. When the length of graft was greater than 15 cm in the SFVFG group, the IFM exceeded 1 mm, but the IFM of the graft in the DBFVFG group was always less than 1 mm. The maximum Von Mises stress of models was frequently located at the second or third pin-bone interface. Thus, external fixation can provide a stable biomechanical environment for the reconstruction of tibial defect by both SFVFG and DBFVFG. The second or third pin-bone interface requires intensive care and that in the reconstruction of tibial defect by SFVFG, the graft length should not exceed 15 cm. PMID:24482691

  6. Think Tank: Identifying and Creating the Next Generation of Community-Based Cancer Prevention Studies | Division of Cancer Prevention

    Cancer.gov

    In late 2015, the NCI Division of Cancer Prevention convened cancer prevention research experts and stakeholders to discuss the current state of cancer prevention research, identify key prevention research priorities for the NCI, and identify studies that could be conducted within the NCI Community Oncology Research Program. Read the Cancer Prevention Research journal article (PDF, 532KB). |

  7. The Influence of Grain Boundaries on Radiation-Induced Point Defect Production in Materials: A Review of Atomistic Studies

    SciTech Connect

    Xian-Ming Bai; Blas P. Uberuaga

    2013-03-01

    Radiation-induced defects cause severe degradation of materials properties during irradiation that can ultimately cause the material to fail. Consequences of these defects include swelling, embrittlement, and undesirable phase transformations. Nanocrystalline materials, which contain a high density of grain boundaries, have demonstrated enhanced radiation tolerance compared to large grain counterparts under certain conditions. This is because, as has long been recognized, grain boundaries can serve as defect sinks for absorbing and annihilating radiation-induced defects. Increasingly, researchers have examined how grain boundaries influence the direct production of defects during collision cascade, the origin of the radiation-induced defects. In this review article, we analyze the computational studies in this area that have been performed during the past two decades. These studies examine defect production near grain boundaries in metallic, ionic, and covalent systems. It is found that, in most systems, grain boundaries absorb more interstitials than vacancies during the defect production stage. While this is generically true of most boundaries, the detailed interaction between defects and grain boundaries does depend on boundary atomic structure, the stress state near the boundary, cascade-boundary separation, and materials properties. Furthermore, the defect distribution near boundaries is qualitatively different from that in single crystals, with the former often exhibiting larger vacancy clusters and smaller interstitial clusters than the latter. Finally, grain boundaries that are damaged after cascades have occurred exhibit different interaction behavior with defects than their pristine counterparts. Together, these atomistic simulation results provide useful insight for both developing higher-level modeling of defect evolution at long timescales and how interfaces influence radiation damage evolution.

  8. Familial recurrence of midline birth defects--a nationwide danish cohort study.

    PubMed

    Oyen, Nina; Boyd, Heather A; Poulsen, Gry; Wohlfahrt, Jan; Melbye, Mads

    2009-07-01

    If birth defects resulting from fusion failure in the midline have a common etiology, as previously hypothesized, persons with a family history of 1 type of midline defect should have an increased risk of dissimilar midline defects. The authors examined this hypothesis by linking information from the National Patient Register, the Causes of Death Register, and the Danish Family Relations Database for all Danish residents registered in the Civil Registration System during 1977-2005. Linkage yielded a cohort of 1.7 million persons with 1 or more relatives, including 9,063 persons with 1 or more midline defects. The authors investigated familial clustering of midline defects by estimating relative risks of similar and dissimilar midline defects according to family history of midline defects. Given a history of similar defects in first-degree relatives, relative risks for neural tube defects, conotruncal defects, oral facial clefts, anal/rectal defects, and diaphragmatic defects were 8.2 (95% confidence interval (CI): 3.1, 21.7), 7.7 (95% CI: 4.3, 13.8), 13.2 (95% CI: 10.8, 16.2), 10.3 (95% CI: 2.6, 41.1), and 11.2 (95% CI: 1.6, 79.7), respectively. However, given a dissimilar defect in a family member, the relative risk for any midline defect was null. Thus, similar defects but not dissimilar defects clustered in families, providing no evidence of a shared etiology for dissimilar midline defects.

  9. A Study of Surfaces, Interfaces and Point Defect Control in III-Nitrides

    NASA Astrophysics Data System (ADS)

    Reddy, Pramod

    Al/Ga-Nitrides are of great importance in deep UV optoelectronics and high power electronics. The current challenges in implementing AlGaN based technologies arise from deleterious effects of surface states and bulk point defects. Consequently, a study of surface/bulk defect properties and their control is of prime importance. In the first section (chapters 2 to 6) of this work, progress in current understanding of the surface of Al/Ga-Nitride and its interface with metals, dielectrics and Al/Ga-nitride is reported. X-ray photoelectron spectroscopy (XPS) is employed to measure surface/interface Fermi level and band alignment. Metal polar, nitrogen polar and nonpolar Al/Ga-Nitride free surface and their heterojunctions grown on sapphire and native AlN single crystalline substrates were characterized. The dependence of surface Fermi level (charge neutrality level (CNL)) on Al composition is found to be linear with Schottky barrier heights at CNL exhibiting an overall quadratic behavior due to bandgap bowing. A general theoretical expression for Schottky barrier heights on AlGaN is then determined as a function of Al composition and metal electronegativity utilizing the interface induced gap states (IFIGS) model and is corroborated with current-voltage-temperature (I-V), capacitance-voltagetemperature and XPS characterization with different metals. The measured CNLs are also used to determine the conduction and valence band offsets in AlGaN heterojunctions according to IFIGS model and their dependence on Al composition is determined. AlGaN is found to exhibit a composition-independent surface work function and an electron affinity which is a linear function of the barrier height at CNL. The origin of the bandgap bowing is found to be in the conduction band. Passivation studies include LPCVD and PECVD silicon nitride and PECVD silicon dioxide deposited on AlxGa1-xN (of varying Al composition 'x'). Among these LPCVD silicon nitride is found to be most promising and

  10. Preventing postoperative congestion in reverse pedicle digital island flaps when reconstructing composite tissue defects in the fingertip: a patient series.

    PubMed

    Matsuzaki, Hironori; Kouda, Hisao; Yamashita, Haruyoshi

    2012-01-01

    For reconstructing an injured fingertip, a reverse pedicle digital island flap can restore excellent function and appearance. However, postoperative flap congestion may lead to flap necrosis. We tested a method for dissecting the vascular pedicle to prevent congestion and to provide more reliable results. Between August 2002 and December 2010, we reconstructed 14 fingertips in 13 patients (average age, 43 years; range, 24 to 68 years; 9 men). Through a small zigzag incision, the digital artery and a 4-mm-wide subcutaneous venous network were elevated in retrograde fashion to facilitate venous drainage. All flaps healed completely without severe congestion or necrosis. Slight flexion contractures remained in the PIP (mean, 12°) and DIP (mean, 14°) joints. Our procedure is simpler and more reliable than other techniques, such as adding a narrow skin bridge to the pedicle or a venous anastomosis to prevent venous congestion, and it assures the survival of the flap.

  11. Mechanism of forming defects in roll-to-roll hot embossing of micro-pyramid arrays: II. Numerical study

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Yi, Peiyun; Deng, Yujun; Peng, Linfa; Lai, Xinmin; Ni, Jun

    2015-11-01

    Roll-to-roll (R2R) hot embossing is a continuous imprinting technique for the replication of large-area microstructures. Polymer deformation and recovery behavior is more complicated in this process than in the traditional plate-to-plate mode, especially for the embossing of 3-dimensional (3D) structures, such as the micro-pyramid structure used for reflective film. As a result, forming defects of poor shape and dimensional accuracy are more likely to emerge and are of greater diversity, which may negatively influence product quality and must be eliminated. In our previous experimental study, we have defined several types of forming defects that are commonly seen in embossed micro-pyramid arrays and have discussed the influence of processing parameters on the forming defects systematically. What is presented in this article is devoted to the simulation analysis of the forming mechanism of three typical types of forming defect: the platform-like defect, the bubble-like defect and the collapse-like defect. A 3D finite element model is established for the simulation analysis, in which the polymer resist is treated as a viscoelastic material based on the general Maxwell model. The simulation results clearly reveal the correlation between the forming defects and the processing conditions, indicating that the platform-like defect and the bubble-like defect are caused by material transport problems while the collapse-like defect results from polymer recovery. The underlying mechanisms for the forming defects disclosed in this research can provide effective guidelines for better process control as well as for improved design of the R2R hot embossing system.

  12. Effects of folic acid awareness on knowledge and consumption for the prevention of birth defects among Hispanic women in several U.S. Communities.

    PubMed

    Prue, Christine E; Hamner, Heather C; Flores, Alina L

    2010-04-01

    The neural tube defects (NTDs) anencephaly and spina bifida, are serious birth defects of the brain and spine that affect about 3000 pregnancies per year in the United States. Research has found a strong link between periconceptional folic acid consumption and NTD prevention. Because Hispanic women have higher rates of NTD-affected births, targeted folic acid promotion efforts were conducted in several major cities from 1999 to 2002. Efforts included paid and unpaid placements of Spanish language public service announcements (PSAs) and community-level education through the use of promotoras. Analyses focused on whether or not women's reported awareness of folic acid, regardless of promotion type, impacted their knowledge or behavior. Women who reported awareness of folic acid had greater folic acid knowledge and use of vitamins containing folic acid than those not aware. Analyses also examined the use of vitamins containing folic acid by pregnancy intention among women who reported awareness of folic acid. The results were varied. Pregnancy wanters were most likely to use vitamins containing folic acid daily. For this group, however, awareness did not play as large a role in whether they reported consuming a vitamin containing folic acid or not, as it did for pregnancy waiters and avoiders.

  13. The reduction of radiation damage in solar cells. A study of radiation defects in silicon

    NASA Astrophysics Data System (ADS)

    Bernard, J.; Reulet, R.; Roux, M.; Bielle-Daspet, D.; Lagouin, M.; Bourgoin, J.; Stievenard, D.; Castaner-Munoz, L.; Alcubilla, R.; Prat, L.

    1983-01-01

    In order to quantitatively predict the degradtion of solar cells under space conditions a theoretical and experimental study was carried out. The effects of resistivity (10 and 1 ohm cm), doping (boron or gallium) and oxygen on the degradation induced by energetic electrons and illumination on silicon solar cells were evaluated. The room temperature degradation of GaAs structures was studied. A Gallium doped silicon appears promising for improved solar cells. Capacitance transient spectroscopy results show that the behavior of hole traps agrees with the variation of the solar cell parameters. The GaAs results indicate that the total recovery of the 1 MeV irradiation defects is obtained by 20 min annealing at 220 C, but defect production and recovery may vary with the structure technology.

  14. Defect induced magnetism in highly oriented pyrolytic graphite: bulk magnetization and 19F hyperfine interaction studies.

    PubMed

    Mohanta, S K; Mishra, S N; Davane, S M; Srivastava, S K

    2012-02-29

    We have made bulk and local investigations on defect induced magnetism in highly oriented pyrolytic graphite (HOPG) irradiated with a 40 MeV carbon beam. The local magnetic response of irradiated HOPG was studied by measuring the hyperfine field of recoil implanted (19)F using γ-ray time differential perturbed angular distribution (TDPAD) measurements. While the bulk magnetic properties of the irradiated sample show features characteristic of room temperature ferromagnetism, the hyperfine field data reflect enhanced paramagnetism with no indication of long range magnetic ordering. The experimental studies are further supported by ab initio density functional calculations. We believe that the ferromagnetic response in irradiated HOPG arises mostly from defect induced magnetic moments of carbon atoms in the near surface region, while those deep inside the host matrix remain paramagnetic.

  15. Defect study in ZnO related structures—A multi-spectroscopic approach

    NASA Astrophysics Data System (ADS)

    Ling, C. C.; Cheung, C. K.; Gu, Q. L.; Dai, X. M.; Xu, S. J.; Zhu, C. Y.; Luo, J. M.; Zhu, C. Y.; Tam, K. H.; Djurišić, A. B.; Beling, C. D.; Fung, S.; Lu, L. W.; Brauer, G.; Anwand, W.; Skorupa, W.; Ong, H. C.

    2008-10-01

    ZnO has attracted a great deal of attention in recent years because of its potential applications for fabricating optoelectronic devices. Using a multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), we have studied the two observed phenomena from ZnO related structures. They namely included the H 2O 2 pre-treatment induced ohmic to rectifying contact conversion on Au/ n-ZnO contact and the p-type doping by nitrogen ion implantation. The aim of the studies was to offering comprehensive views as to how the defects influenced the structures electrical and optical properties of the structures. It was also shown that PAS measurement using the monoenergetic positron beam could offer valuable information of vacancy type defects in the vertical ZnO nanorod array structure.

  16. Bioactive glass in cavitary bone defects: a comparative experimental study in rabbits

    PubMed Central

    Camargo, André Ferrari de França; Baptista, André Mathias; Natalino, Renato; de Camargo, Olavo Pires

    2015-01-01

    OBJECTIVES: To compare bioactive glass and autograft regarding their histomorphometric characteristics. METHODS: The authors conducted a prospective case-control experimental study on animals in order to compare the histomorphometric characteristics of bioactive glass versus autograft. Eight rabbits underwent surgery in which a cavitary defect was created in both proximal femurs. One side was filled with bioactive glass granules and the other, with autograft grafted from the contralateral side. The sides were randomized. Fourteen days after surgery, the animals were euthanized. RESULTS: Histologic analysis revealed that bone neoformation was equivalent among the two groups and the osteoblasts cell-count was higher in the femurs treated with bioactive glass. The osteocytes cell-count, however, was lower. The similarity in bone formation between both groups was consistent to literature findings. CONCLUSION: Bioactive glass is similar to autograft regarding bone neoformation in this animal model of cavitary bone defects. Level of Evidence III, Case-Control Study. PMID:26327802

  17. The epidemiology of cardiovascular defects, part 2: a study based on data from three large registries of congenital malformations.

    PubMed

    Harris, J A; Francannet, C; Pradat, P; Robert, E

    2003-01-01

    There were three objectives of this study: to investigate possible specificity in the association between specific cardiac defects and chromosomal anomalies; to evaluate ways of categorizing cardiac defects into larger groups with epidemiological similarities that could indicate similarities in etiology or pathogenesis; and to analyze the relationship between specific cardiac defects and diabetes. We pooled data on infants (aged 1 year or younger) with congenital cardiovascular defects from three large birth defect registries in California, Sweden, and France. The registries in Sweden and France obtained data through reporting from various sources; in California, medical records were reviewed. For severe congenital heart defects, the percentage of infants with identified chromosomal anomalies varied between 0.9% for d-TGV to 68.4% for ECD. In general, specific cardiac conditions have different risk factors. For example, conotruncal defects have been traditionally grouped, but the data presented in this paper indicates more differences for risk factors for the components of conotruncal defects: tetralogy of Fallot, d-TGV, common truncus, and DORV. In general, we suggest the strategy of "splitting" rather than "lumping" when searching for specific genetic factors and/or teratogens. Adequate analysis thus requires large registries or collaboration among registries. The findings did not support constellations between mothers' diabetes and specific defects.

  18. Quantum-defect studies of systematic trends of f-values. Transitions in subordinate spectral series.

    NASA Astrophysics Data System (ADS)

    Barrientos, C.; Martín, I.

    1992-09-01

    Oscillator strengths for transitions in the sharp and diffuse series of several members of the lithium isoelectronic sequence have been computed in the length and velocity forms through the Quantum Defect Orbital (QDO) formalism. A core-polarization correction to the dipole moment transition operator has also been included. The dependence of the f-values on the reciprocal of the nuclear charge in the sequence has also been studied.

  19. Ab initio molecular dynamics study of topological defects in polyethylene strands

    NASA Astrophysics Data System (ADS)

    Saitta, Antonino Marco; Klein, Michael L.

    2000-03-01

    The mechanical resistance of polyethylene strands subject to tension and the way their properties are affected by the presence of knots(Nature 399), 46 (1999); JCP 111, 9434 (1999). and entanglements(JPCB, in press) (2000). are studied using first-principles molecular dynamics calculations. The presence of topological defects significantly weakens the chain strength, and the radicals generated at the rupture undergo a series of unexpected ``femto'' chemical reactions(JACS 121), 11827 (1999)..

  20. The numerical study of first order wetting transition with two defect lines

    NASA Astrophysics Data System (ADS)

    Wu, X. T.

    2016-09-01

    The first order wetting transition with two defect lines, one near a wall and another at a distance N1, in the d = 2 Ising model is studied by the bond propagation algorithm. The numerical calculations are carried out on very large lattices with size up to 1602 × 160. The finite size effects of the first order transition in that model are discussed. The magnetization profile is also calculated. The numerical results agree with the exact results very well.

  1. Genetic ablation of cyclophilin D rescues mitochondrial defects and prevents muscle apoptosis in collagen VI myopathic mice.

    PubMed

    Palma, Elena; Tiepolo, Tania; Angelin, Alessia; Sabatelli, Patrizia; Maraldi, Nadir M; Basso, Emy; Forte, Michael A; Bernardi, Paolo; Bonaldo, Paolo

    2009-06-01

    Ullrich congenital muscular dystrophy (UCMD) and Bethlem myopathy are inherited muscle disorders caused by mutations of genes encoding the extracellular matrix protein collagen VI (ColVI). Mice lacking ColVI (Col6a1(-/-)) display a myopathic phenotype associated with ultrastructural alterations of mitochondria and sarcoplasmic reticulum, mitochondrial dysfunction with abnormal opening of the permeability transition pore (PTP) and increased apoptosis of muscle fibers. Treatment with cyclosporin (Cs) A, a drug that desensitizes the PTP by binding to cyclophilin (Cyp)-D, was shown to rescue myofiber alterations in Col6a1(-/-) mice and in UCMD patients, suggesting a correlation between PTP opening and pathogenesis of ColVI muscular dystrophies. Here, we show that inactivation of the gene encoding for Cyp-D rescues the disease phenotype of ColVI deficiency. In the absence of Cyp-D, Col6a1(-/-) mice show negligible myofiber degeneration, rescue from mitochondrial dysfunction and ultrastructural defects, and normalized incidence of apoptosis. These findings (i) demonstrate that lack of Cyp-D is equivalent to its inhibition with CsA at curing the mouse dystrophic phenotype; (ii) establish a cause-effect relationship between Cyp-D-dependent PTP regulation and pathogenesis of the ColVI muscular dystrophy and (iii) validate Cyp-D and the PTP as pharmacological targets for the therapy of human ColVI myopathies.

  2. Study of the interplay between N-graphene defects and small Pd clusters for enhanced hydrogen storage via a spill-over mechanism.

    PubMed

    Rangel, E; Sansores, E; Vallejo, E; Hernández-Hernández, A; López-Pérez, P A

    2016-12-07

    The hydrogen spill-over mechanism was studied by applying Density Functional Theory. We used small palladium clusters to act as the catalyst supported on the substrate (comprised of pyridinic and pyrrolic nitrogen doped graphene), in order to study hydrogen dissociation, migration and diffusion. Charge transfer and strong binding between the catalyst and the substrate lead to dissociated states of H2 and prevent clusters from detaching and coalescing. In dissociated cases of H2 on Pd clusters, energy barriers below 0.6 eV were found. Likewise, concerning hydrogen migration from the catalyst to the substrate, energy barrier values of 0.8 eV (pyridinic defect) and 0.5 eV (pyrrolic defect) were apparent in the case of the Pd4 cluster at full hydrogen saturation. This indicates that hydrogen dissociation and migration may occur spontaneously at room temperature. This result shows that the interaction between the defects and the small metal clusters may explain the role that defects play in hydrogen migration from the catalyst to the substrate. Subsequently, it was found that thermal desorption does not limit chemisorbed hydrogen diffusion on the substrate. This work may thus help to determine experimental strategies with the capacity to enhance hydrogen storage.

  3. Thermoluminescence and defect study of MgSiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Nagabhushana, H.; Nagabhushana, B. M.; Umesh, B.; Premkumar, H. B.; Anil, Nalina; Gundu Rao, T. K.; Chakradhar, R. P. S.

    2010-04-01

    Enstatite (MgSiO3) ceramic powders were synthesised by a low-temperature initiated self-propagating, gas-producing solution combustion process. The prepared powders were characterised by powder X-ray diffraction, scanning electron microscopy and Brunauer-Emmer-Teller specific surface area measurements. Defect centres induced by radiation were studied using the techniques of thermoluminescence (TL) and electron spin resonance (ESR). A well-resolved glow with peak at 178°C and a shouldered peak at 120°C were observed. Two defect centres were identified by ESR measurements, which were carried out at room temperature, and these were assigned to an O- ion and F+ centre. The O- ion (hole centre) appears to correlate with the main TL peak at 178°C.

  4. Thermal annealing of C ion irradiation defects in nuclear graphite studied by positron annihilation

    NASA Astrophysics Data System (ADS)

    Shi, C. Q.; Schut, H.; Li, Z. C.

    2016-01-01

    In order to investigate the thermal behaviour of radiation induced point defects in nuclear graphite, ETU10 graphite was implanted with 350 keV C+ ion to doses of 1015 and 1016 cm-2. The point defects introduced by the implantation were characterized by Positron Annihilation Doppler Broadening (PADB) and their thermal behaviour was studied during “in situ” annealing at Delft Variable Energy Positron beam (VEP). The annealing was performed for 5 minutes at temperatures ranging from 300 K (as implanted) to 1500 K in steps of 100 K. For both doses, an annealing stage at around 450 K is observed followed by a second stage around 700 K. For the high dose implantation vacancy complexes are found which are stable up to a temperature around 1400K.

  5. Density functional study of H-induced defects as nucleation sites in hybrid carbon nanomaterials.

    SciTech Connect

    Barnard, A.; Terranova, M. L.; Rossi, M.; Dip. Scienze e Tecnologie Chimiche; Dip di Energetica; INFM

    2005-01-01

    Recently we have reported on the growth of an exciting new class of hybrid nanostructured carbon materials, coupling nanosized diamond with single-walled carbon nanotubes. The inner structures were shown to be single-walled C nanotubes or bundles of single-walled nanotubes up to 15 {micro}m long, and the outer deposit consisted of faceted diamond crystallites with diameters in the range of 20-100 nm. To aid in understanding the mechanisms responsible for the formation of such materials, the present study uses density functional theory to examine the role of atomic hydrogen in creating localized sp{sup 3} hybridized defects on the outer wall of carbon nanotubes. The results illustrate that certain absorption configurations may produce defects containing dangling carbon bonds, and thus promote the formation of suitable sites for nanodiamond nucleation.

  6. [Study on one stage reconstruction of cranial base defects with ADM].

    PubMed

    Wang, Weiwei; Lou, Weihua; Wang, Liang; Lu, Wuhao; Li, Tao

    2013-06-01

    The purpose of this study is to explore the effect of reconstruction for the nose cranial base defects after removal of tumor with ADM. Thirteen patients with the nose skull base defects after tumors resection underwent cranial base reconstruction with ADM at the same time. Postoperatively, routine endoscopic and CT scan were performed on all patients at regular intervals. The successful cranial base reconstruction was achieved in 13 patients with ADM. Intracranial infection occurred in 3 patients and recovered after two weeks postoperatively, given combination of antibiotics, dexamethasone anti-inflammatory, mannitol, reduce intracranial pressure with diuretics and cooling, sedation processing. All patients developed no delayed complications. Our experience has demonstrated that the cranial base reconstruction with the ADM "I" shaped sandwich has harvest the satisfactory effect.

  7. Indium-defect interactions in FCC and BCC metals studied using the modified embedded atom method

    NASA Astrophysics Data System (ADS)

    Zacate, M. O.

    2016-12-01

    With the aim of developing a transferable potential set capable of predicting defect formation, defect association, and diffusion properties in a wide range of intermetallic compounds, the present study was undertaken to test parameterization strategies for determining empirical pair-wise interaction parameters in the modified embedded atom method (MEAM) developed by Baskes and coworkers. This report focuses on indium-solute and indium-vacancy interactions in FCC and BCC metals, for which a large set of experimental data obtained from perturbed angular correlation measurements is available for comparison. Simulation results were found to be in good agreement with experimental values after model parameters had been adjusted to reproduce as best as possible the following two sets of quantities: (1) lattice parameters, formation enthalpies, and bulk moduli of hypothetical equiatomic compounds with the NaCl crystal structure determined using density functional theory and (2) dilute solution enthalpies in metals as predicted by Miedema's semi-empirical model.

  8. DLTS study of defects in hydrogen plasma treated p-type silicon

    NASA Astrophysics Data System (ADS)

    Wu, L.; Leitch, A. W. R.

    2001-12-01

    A deep level transient spectroscopy (DLTS) study of defects found in float-zone p-type silicon exposed to a DC hydrogen plasma is reported. DLTS measurements of these samples revealed three deep levels. Two of the levels are broad, with ET- EV in the range 0.34-0.39 eV (H2) and 0.40-0.44 eV (H3); these appear as bands in the Arrhenius plot. The third level has an activation energy of 0.09 eV (H1). The variations in the capture cross-sections of H2 and H3 are believed to be strain-related. The concentration of H3 exceeds the other two levels and decreases rapidly into the samples with ∼10 15 cm -3 at a depth of 0.20 μm. H3 is tentatively ascribed to an extended defect.

  9. X-ray topographic study of growth defects of trans-stilbene crystals grown from solutions

    NASA Astrophysics Data System (ADS)

    Klapper, Helmut; Zaitseva, Natalia; Carman, Leslie

    2015-11-01

    Single crystals of trans-stilbene, C14H12, with properties suitable for high-energy neutron detection were grown from solution in anisole and toluene by the temperature reduction method with growth rates up to 6 mm/day. From these crystals, slices of appropriate orientation and thickness of 2-4 mm were cut and studied by X-ray diffraction topography applying the Lang method using CuKα radiation. The topographs exhibit growth defects such as liquid inclusions, dislocations, striations, and faulty growth-sector boundaries. These defects occur in the same typical arrangements and geometries as is observed in all kinds of crystals grown on habit faces from solution. Besides growth dislocations originating from inclusions and propagating with the growth front, many plastic glide dislocations in the shape of loops or half-loops emitted from inclusions by stress relaxation are observed. The glide system underlying this plasticity is discussed.

  10. First-principles study on native point defects of cubic cuprite Ag2O

    NASA Astrophysics Data System (ADS)

    Yin, Yuan; Chen, Guangde; Duan, Xiangyang; Ye, Honggang; Jin, Wentao; Zhu, Youzhang; Wu, Yelong

    2016-12-01

    Using the first-principles calculations, we have systematically investigated the atomic configurations, electronic structures, formation energies and transition energies of native point defects in cuprite Ag2O. Under the conditions of Ag-rich, we find that the oxygen vacancy (VO) and the oxygen interstitial (Oi) have the lowest formation energies in p-type and n-type conditions, respectively. Silver vacancy (VAg) acts as a shallow acceptor, which has high formation energy in p-type sample. Oxygen anti-site (OAg) is the most stable state and acts as an acceptor-type point defect in the O-rich conditions. Ag interstitial (Agi) is a shallow donor, which can be formed easily in the Ag-rich conditions. Moreover, we study the band offsets of heterojunction between Ag2O in cuprite structure and ZnO, GaN, and AlN in the wurtzite structure. These results would provide guidance for the experimental studies of point defects in cuprite Ag2O.

  11. Prevention

    Treesearch

    Kerry Britton; Barbara Illman; Gary Man

    2010-01-01

    Prevention is considered the most cost-effective element of the Forest Service Invasive Species Strategy (USDA Forest Service 2004). What makes prevention difficult is the desire to maximize free trade and the resulting benefits to society while, at the same time, protecting natural resources. The role of science is to first identify which commodities pose an...

  12. A Study of Handling Cytotoxic Drugs and Risk of Birth Defects in Offspring of Female Veterinarians

    PubMed Central

    Shirangi, Adeleh; Bower, Carol; Holman, C. D’Arcy J.; Preen, David B.; Bruce, Neville

    2014-01-01

    We examined the association of occupational exposure to handling cytotoxic drugs at work with risk of birth defects among a cohort of female veterinarians. This study is a follow up survey of 321 female participants (633 pregnancies) who participated in the Health Risks of Australian Veterinarian project. Data on pregnancies and exposure during each pregnancy was obtained by self-administered mailed questionnaire. Female veterinarians handling cytotoxic drugs during their pregnancy had a two-fold increased risk of birth defects in their offspring (RR = 2.08, 95% CI (1.05–4.15)). Results were consistent in subgroup analysis of those who graduated during the period of 1961 to 1980 (RR = 5.04, 95% CI (1.81, 14.03) and in those working specifically in small and large animal practice. There was no increased risk in the subgroup that graduated after 1980. Women with unplanned pregnancies were more likely to handle cytotoxic drugs on a daily basis (RR = 1.86, 95% CI, 1.00–3.48) and had a higher increased risk of birth defects than those who planned their pregnancies in recent graduates and in those who worked specifically in small animal practice (RR = 2.53, 95% CI, 1.18–5.42). This study suggests that the adverse effects of handling cytotoxic drugs in pregnant women may include an increased risk of birth defects. Pregnancy intention status is an important health behavior and should be considered in prenatal programs. PMID:24927037

  13. Comparative study of the transcatheter and transthoracic device closure treatments for atrial septal defect

    PubMed Central

    Chen, Qiang; Cao, Hua; Chen, Zhao-yang; Zhang, Gui-Can; Chen, Liang-wan; Xu, Fan; He, Jia-jun

    2017-01-01

    Abstract The purpose of this study was to compare patient populations, safety, feasibility, complications, and total costs of the transcatheter and transthoracic device closure treatments for secundum atrial septal defect. From January 2014 to December 2014, we enrolled 155 patients with secundum atrial septal defects in our hospital. The patients were divided into 2 groups: the 70 patients in group A underwent transcatheter device closure, and the 85 patients in group B underwent transthoracic intraoperative device closure with a right lateral mini-thoracotomy. In group A, the total occlusion rate was 94.3% immediately after the operation, 100% at 3 months, and 100% at 12 months of follow-up; the group A results were not statistically different from the group B results (94.1%, 98.8%, 98.8%, respectively). There was a statistically significant difference in the minor complication rate (P < 0.05), and there were no reported deaths. There was a greater indicated scope using the transthoracic closure device to treat atrial septal defects. In our comparative study, the patients in group B had longer intensive care unit stays and hospital stays than group A (P < 0.05). Both of the device closure treatment options for secundum atrial septal defect are safe and feasible. The transcatheter device closure approach has the advantages of more cosmetic results, less trauma, and a shorter hospital stay than the transthoracic approach. On the contrary, the transthoracic closure device is an economical alternative choice, particularly for patients who are not eligible for the transcatheter closure device. PMID:28296745

  14. Use of cultured mucosal grafts to cover defects caused by vestibuloplasty: an in vivo study.

    PubMed

    Raghoebar, G M; Tomson, A M; Scholma, J; Blaauw, E H; Witjes, M J; Vissink, A

    1995-08-01

    In oral and maxillofacial surgery palatal mucosal grafts are routinely used to cover mucosal defects caused by vestibuloplasty. However, the quantity of palatal mucosa is a limiting factor in more extensive operations. This study investigated whether autologous cultured sheets of mucosa can serve as a dressing for these wounds. Punch biopsies (diameter, 4 mm) were taken from the hard palate of eight patients (five men, three women; mean age 43 years). Epithelial cells were enzymatically dissociated from these tissue specimens and grown in vitro in the presence of a fibroblast feeder layer. Within 3 weeks, a transplantable epithelial sheet of about 20 cm2 was obtained. The sheet was detached from the culture flask by enzyme treatment and fixed to a carrier of Vaseline (Cheeseborough Ponds Inc, Greenwich, CT) gauze. Using a split-mouth technique, the sheet was placed on half of a mucosal defect created by vestibuloplasty, while the other half of the defect was covered by a conventional split-thickness palatal graft. Both the cultured and conventional graft were held in place by the patient's relined denture fixed with perimandibular sutures. One week postsurgery, the denture and Vaseline gauze were removed. Three months after vestibuloplasty, biopsy specimens of each grafted site were taken and processed for light and transmission electron microscopy (LM, TEM). Three months postsurgery, the grafted mucosa of both sites bore close resemblance to palatal mucosa. Both the cultured and split-thickness grafts were vascularized, did not evoke a homograft reaction, and showed a smooth graft/lip mucosal junction and minimal wound contraction. LM and TEM revealed that both types of grafts formed a fully differentiated keratinizing mucosa with a well-developed basement membrane and rete ridges, comparable with the histology and ultrastructure of palatal mucosa in situ. It was concluded from this study that cultured mucosa can serve as a proper dressing for mucosal defects

  15. Obesity Prevention Opinions of School Stakeholders: A Qualitative Study

    ERIC Educational Resources Information Center

    Della Torre, Sophie Bucher; Akre, Christina; Suris, Joan-Carles

    2010-01-01

    Background: In general, schools are an important setting to implement current recommendations for obesity prevention in children because the vast majority of children attend school. This study investigated the opinions of different school stakeholders on the feasibility and acceptability of current obesity prevention strategies that could be…

  16. Obesity Prevention Opinions of School Stakeholders: A Qualitative Study

    ERIC Educational Resources Information Center

    Della Torre, Sophie Bucher; Akre, Christina; Suris, Joan-Carles

    2010-01-01

    Background: In general, schools are an important setting to implement current recommendations for obesity prevention in children because the vast majority of children attend school. This study investigated the opinions of different school stakeholders on the feasibility and acceptability of current obesity prevention strategies that could be…

  17. A newborn lethal defect due to inactivation of retinaldehyde dehydrogenase type 3 is prevented by maternal retinoic acid treatment

    PubMed Central

    Dupé, Valérie; Matt, Nicolas; Garnier, Jean-Marie; Chambon, Pierre; Mark, Manuel; Ghyselinck, Norbert B.

    2003-01-01

    The retinoic acid (RA) signal, produced locally from vitamin A by retinaldehyde dehydrogenase (Raldh) and transduced by the nuclear receptors for retinoids (RA receptor and 9-cis-RA receptor), is indispensable for ontogenesis and homeostasis of numerous tissues. We demonstrate that Raldh3 knockout in mouse suppresses RA synthesis and causes malformations restricted to ocular and nasal regions, which are similar to those observed in vitamin A-deficient fetuses and/or in retinoid receptor mutants. Raldh3 knockout notably causes choanal atresia (CA), which is responsible for respiratory distress and death of Raldh3-null mutants at birth. CA is due to persistence of nasal fins, whose rupture normally allows the communication between nasal and oral cavities. This malformation, which is similar to isolated congenital CA in humans and may result from impaired RA-controlled down-regulation of Fgf8 expression in nasal fins, can be prevented by a simple maternal treatment with RA. PMID:14623956

  18. First Principles Study on Orientational Defects in Ice Ih: Effect of Adsorbates

    NASA Astrophysics Data System (ADS)

    Maşlakcı, Z.; Uras-Aytemiz, N.

    2009-04-01

    Orientational, Bjerrum, defects in ice are the intrinsic property and believed that the reason of proton conductivity in ice [1]. In this study, energy of formation and dynamics of the Bjerrum defects were investigated in the presence of small adsorbates, such as dimethyl ether, CO2 etc.. The main tool of this investigation is ab initio molecular dynamics as implemented in the density functional code QUICKSTEP [2] which is part of CP2K package [3]. A crystal slab of three bilayers of hexagonal ice containing 72 water molecules were used as a model. The energy cost for the formation of orientation defects that are solvated by adsorbates as well as trajectories calculated on DFT level will be presented. 1. Petrenko V. F. and Whitworth R. W., Physics of Ice Oxford University Press, Oxford, 1999. 2. CP2K, http://cp2k.berlios.de (2000-2004) 3. VandeVondele, J.; Krack M.; Mohamed F.; Parrinello M.; Chassaing T.; Hutter J. Comp. Phys. Comm. 2005, 167, 103.

  19. Reconstruction of intraoral defects with superior labial artery musculo-mucosal flap: a preliminary clinical study.

    PubMed

    Güven, Erdem; Uğurlu, Alper Mete; Başaran, Karaca; Basat, Salih Onur; Yiğit, Bariş; Hafiz, Günter; Kuvat, Samet Vasfi

    2010-01-01

    In this article, we present the use of the superior labial artery musculo-mucosal (SLAMM) flap for intraoral reconstruction. The study included five patients (2 females, 3 males; mean age 36 years; range 11 to 56 years) who consulted at our clinic between October 2008 and January 2010. Five oral defects were reconstructed with the SLAMM flap. Three patients underwent reconstruction with SLAMM flap following oncologic resection. The other two patients had traumatic defects in the oral cavity which necessitated flap application. First, the distal end of the flap was incised and the superior labial artery was identified after dissection. After ligation of the artery, the mucosa, submucosa and the cuff of orbicularis oris muscle were elevated. The dissection was extended laterally and anteriorly, depending on the necessary flap size. None of the patients had partial or total flap necrosis. During the follow-up period, contracture developed in only one patient. Successful reconstruction was observed in all patients. The superior labial artery musculo-mucosal flap is a simple and feasible technique which can be used for reconstruction of intraoral defects.

  20. Behavior of bioactive glass-ceramic implanted into long bone defects: a scintigraphic study.

    PubMed

    Sponer, Pavel; Urban, Karel; Urbanová, Elen; Karpas, Karel; Mathew, Pradeep George

    2010-01-01

    The purpose of the study was to assess the long-term behavior and incorporation of the bioactive oxyhydroxyapatite glass-ceramic used to fill defects of long bones after curettage of bone cysts in 17 patients. The method of evaluation was a three-phase bone scintigraphy combined with radiographic and clinical evaluation. At a mean follow-up of 7 years, the glass-ceramic material had been completely incorporated. Mean uptake ratio was 1.31+/-0.25 after implantation of glass-ceramic in the metaphyseal region and 2.07+/-0.62 after implantation of glass-ceramic in the diaphyseal region (P<0.05). Mean uptake ratio was 1.40+/-0.30 in patients without persistent pain and 2.07+/-0.69 in patients who complained of pain in the area of synthetic filling (P<0.05). The bioactive glass-ceramic can be implanted into the metaphyseal defects of long bones, but this material is not suitable for filling the diaphyseal defects.

  1. Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy.

    PubMed

    König, Thomas; Simon, Georg H; Heinke, Lars; Lichtenstein, Leonid; Heyde, Markus

    2011-01-01

    Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001) and line defects in aluminum oxide on NiAl(110), respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM) and the electronic structure by scanning tunneling spectroscopy (STS). On magnesium oxide, different color centers, i.e., F(0), F(+), F(2+) and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F(2+)-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.

  2. STM study on the surface defects of SnSe induced by thermal annealing

    NASA Astrophysics Data System (ADS)

    Thi Ly, Trinh; Kim, Sang-Ui; Kim, Tae Hoon; Duong, Anh Tuan; Cho, Sunglae; Rhim, S. H.; Kim, Jungdae

    SnSe is a IV - VI semiconductor with 0.86 eV gap, and a single crystal SnSe usually exhibits a p-type characteristic. SnSe is one of 2D layered materials, and it has attracted researchers' attentions due to excellent physical properties for future applications. In particular, exceptionally high ZT value (ZT = ~2.6 at 923 K) was reported for SnSe single crystal (Zhao et al., Nature 508 373 (2014). Even though many researches on SnSe have proposed the possibilities of various applications so far, surprisingly little information is available regarding the microscopic structure of SnSe surfaces. We conducted a systematic study on the surface defect of SnSe induced by thermal annealing via a home-built low temperature scanning tunneling microscopy (STM). Various defects were characterized by STM/STS, and we found that Sn vacancy is a dominating intrinsic defect. The size of vacancy was changed after annealing process in UHV at different temperatures. This work was supported by the National Research Foundation of Korea(NRF) [Nos. NRF-2013R1A1A1008724, NRF-2009-0093818, and NRF-2014R1A4A1071686].

  3. Photoluminescence Studies of Point Defects in ZnGeP_2

    NASA Astrophysics Data System (ADS)

    Giles, N. C.; Halliburton, L. E.; Schunemann, P. G.; Pollak, T. M.

    1996-03-01

    Zinc germanium diphosphide (ZnGeP_2) is a II-IV-V2 ternary chalcopyrite sem iconductor, and is a prime candidate for frequency-conversion applications in th e mid-infrared. Device performance at high powers has been hampered by a near-i nfrared absorption band. We present a photoluminescence (PL) study performed on a series of bulk ZnGeP2 single crystals grown by the horizontal gradient-fre eze technique. Two broad overlapping emission bands are observed at about 1.4 e V and 1.6 eV. PL data have been recorded as a function of temperature, excitati on power density, and excitation wavelength. An analysis of the polarization of the emitted PL reveals two distinct transitions. The PL data are correlated wi th electron paramagnetic resonance data, which identified zinc vacancies and pho sphorus vacancies as the dominant acceptor and donor centers in these samples. The PL data thus provide electronic energy levels related to these defect center s and give the crucial tie between defect identification and ab sorption measurements. A comparison between PL and paramagnetic defects in self -nucleated crystals will also be presented. Work supported by NSF (DMR-9409276) and NASA (NCCW-0051).

  4. Photoluminescence study of self-interstitial clusters and extended defects in ion-implanted silicon

    NASA Astrophysics Data System (ADS)

    Giri, P. K.

    2003-12-01

    We report on the photoluminescence (PL) studies of self-interstitial (I) clustering in ion-implanted Si at various stages of post-implantation annealing. Low-temperature PL measurements on as-implanted and low-temperature annealed (up to 450°C) samples show sharp X and W bands at 1200 and 1218 nm which are attributed to I4 and I3 clusters, respectively. Annealing at 600°C shows a drastic change in the PL spectra. In case of high-energy self-ion-implanted samples, 600°C annealing produces several peaks in the range 1250-1400 nm. For longer duration annealing, two broad bands form at 1322 and 1392 nm irrespective of the ion fluence. These PL signatures are attributed to I8 clusters and/or (1 0 0) I-chains, and they are believed to be the precursor of {3 1 1} rod-like defects. For annealing above 600°C and for fluence ⩾1×1013 cm-2, a sharp PL band is observed at 1376 nm and it is attributed to {3 1 1} rod-like defects. At higher fluences, an additional broad band appears in the PL spectrum at ∼1576 nm which is related to residual ion-damage or extended defect formation. These results illustrate the potential of silicon I-clusters as a possible source of light emission from Si.

  5. First-principles study of point defects in chalcopyrite ZnSnP2

    NASA Astrophysics Data System (ADS)

    Kumagai, Yu; Choi, Minseok; Nose, Yoshitaro; Oba, Fumiyasu

    2014-09-01

    Chalcopyrite ZnSnP2 is an alternative photoabsorber material for solar cells because of its controllable band gap, high absorption coefficient, and earth abundant constituents. In this study we systematically investigate its native point defects including vacancies, interstitials, and antisites using first-principles calculations with the Heyd-Scuseria-Ernzerhof hybrid functional. We evaluate the defect formation energies and defect single-particle levels at the dilute limit using finite-size image-charge corrections and compare them with those reported for CuInSe2 and CuGaSe2. The most likely donors and acceptors are cation antisites, Sn-on-Zn and Zn-on-Sn, respectively. Because of their significantly low formation energies, they lead to Fermi level pinning in the band gap under any growth condition, and constrain the carrier concentration. The Sn-on-Zn antisite in the neutral charge state becomes an intrinsic DX center, a complex of the Sn interstitial and Zn vacancy, and shows a deep donor level as reported for CuGaSe2.

  6. Adsorption Study of a Water Molecule on Vacancy-Defected Nonpolar CdS Surfaces

    PubMed Central

    2017-01-01

    A detailed understanding of the water–semiconductor interface is of major importance for elucidating the molecular interactions at the photocatalyst’s surface. Here, we studied the effect of vacancy defects on the adsorption of a water molecule on the (101̅0) and (112̅0) CdS surfaces, using spin-polarized density functional theory. We observed that the local spin polarization did not persist for most of the cationic vacancies on the surfaces, unlike in bulk, owing to surface reconstructions caused by displaced S atoms. This result suggests that cationic vacancies on these surfaces may not be the leading cause of the experimentally observed magnetism in CdS nanostructures. The surface vacancies are predominantly nonmagnetic except for one case, where a magnetic cationic vacancy is relatively stable due to constraints posed by the (101̅0) surface geometry. At this particular magnetic defect site, we found a very strong interaction with the H2O molecule leading to a case of chemisorption, where the local spin polarization vanishes concurrently. At the same defect site, adsorption of an O2 molecule was also simulated, and the results were found to be consistent with experimental electron paramagnetic resonance findings for powdered CdS. The anion vacancies on these surfaces were always found to be nonmagnetic and did not affect the water adsorption at these surfaces. PMID:28539988

  7. A novel silk fibroin nanofibrous membrane for guided bone regeneration: a study in rat calvarial defects

    PubMed Central

    Lu, Shijun; Wang, Peng; Zhang, Feng; Zhou, Xichao; Zuo, Baoqi; You, Xinran; Gao, Yang; Liu, Hongchen; Tang, Hailiang

    2015-01-01

    A novel membrane for guided bone regeneration (GBR), constituting silk fibroin (SF) nanofiber from native silk nanofibril solution, was prepared by electrospinning process. Another barrier membrane, a collagen-type membrane (Bio-Gide®), was used as a comparative sample. Twelve healthy male Sprague-Dawley rats were used in this study. Bilateral round defects were created in the calvarial bone. The bone regenerative efficacy was evaluated in rat calvarial defects. Animals were killed at 4 and 12 weeks. Bone regeneration was analyzed using micro-computed tomography and histological analysis. The SF nanofibrous membrane showed superior results with regard to mechanical tensile properties. At 4 weeks, the bone volume and collagen I positive areas in the SF group were greater than in the Bio-Gide group. At 12 weeks, the defect had completely healed with new bone in both the groups. In conclusion, the SF nanofibrous membranes showed satisfactory mechanical stability, good biocompatibility, slow degradability, and improved new bone regeneration without any adverse inflammatory reactions. Considering the low cost and low risk of disease transmission, the SF nanofibrous membrane is a potential candidate for GBR therapy compared with the widely used collagen membranes. PMID:26807172

  8. Comparative study of nonabsorbable and absorbable barrier membranes in periodontal osseous defects by guided tissue regeneration

    PubMed Central

    Kaushal, Shalini; Kumar, Avadhesh; Khan, M.A.; Lal, Nand

    2016-01-01

    Background Periodontal invasion of furcation area in multirooted teeth represents one of the most demanding therapeutic challenges in periodontics. Furcation therapy includes various treatment modalities like either maintenance or elimination of furcation or increased access to furcation area. Recent treatment modalities include regenerative procedures like placement of different type of bone grafts with nonabsorbable or absorbable barrier membranes, through guided tissue regeneration. This study compared the clinical efficacy of nonabsorbable barrier membrane with absorbable membrane when used with hydroxyapatite bone graft (G-Graft) in grade II buccal furcation defects in mandibular 1st molars. Materials and methods Fourteen subjects with bilateral grade II buccal furcation defects in lower 1st molars were selected and treated in a split-mouth design. After phase I therapy, molars were divided randomly into two groups for the treatment with either resorbable or nonresorbable membrane in conjunction with G-Graft in both groups. Results All the clinical parameters recorded showed statistically significant improvement in both the groups but no significant difference between two groups was observed. Conclusion Both nonabsorbable and absorbable barrier membranes were equally effective in treating grade II buccal furcation defects in lower molars when used in conjunction with G-Graft except with respect to horizontal bone fill in which absorbable barrier membrane showed better results. PMID:27195208

  9. Ab initio study of point defects near stacking faults in 3C-SiC

    DOE PAGES

    Xi, Jianqi; Liu, Bin; Zhang, Yanwen; ...

    2016-07-02

    Interactions between point defects and stacking faults in 3C-SiC are studied using an ab initio method based on density functional theory. The results show that the discontinuity of the stacking sequence considerably affects the configurations and behavior of intrinsic defects, especially in the case of silicon interstitials. The existence of an intrinsic stacking fault (missing a C-Si bilayer) shortens the distance between the tetrahedral-center site and its second-nearest-neighboring silicon layer, making the tetrahedral silicon interstitial unstable. Instead of a tetrahedral configuration with four C neighbors, a pyramid-like interstitial structure with a defect state within the band gap becomes a stablemore » configuration. In addition, orientation rotation occurs in the split interstitials that has diverse effects on the energy landscape of silicon and carbon split interstitials in the stacking fault region. Moreover, our analyses of ionic relaxation and electronic structure of vacancies show that the built-in strain field, owing to the existence of the stacking fault, makes the local environment around vacancies more complex than that in the bulk.« less

  10. Developmental defects of enamel in primary teeth - findings of a regional German birth cohort study.

    PubMed

    Wagner, Yvonne

    2016-07-07

    The aim was to assess the prevalence, distribution and associated risk factors of developmental defects of enamel (DDE) in 3-year-old Thuringian children in 2013 as part of a prospective cohort study. The subjects (n = 377) were all participants in a Thuringian oral health programme. Children of the birth cohort 2009/2010 were invited to dental examination in the first year of life, followed up with continuous dental care over the next 3 years. Dental caries was scored using the WHO diagnostic criteria expanded to the d1-level without radiography. Enamel defects were assessed according to the modified DDE Index. Data were analysed statistically (multivariate logistic regression). The children were aged 3.3 ± 0.7 years and 52.5 % of them were male. Caries prevalence was 15.6 % and caries experience 0.9 ± 3.3 d1-4mfs. The prevalence of DDE was 5.3 % with an average of 2.7 (±1.4) affected teeth. Second primary molars were the most affected teeth and demarcated opacities the most prevalent type. No child had Amelogenesis imperfecta and six children showed hypomineralised second primary molars. Enamel defects were associated with preterm birth (p = 0.024; OR = 4.9) and hospitalisation in the first year of life (p = 0.013; OR = 4.6). A relatively small proportion of 3-year-old Thuringian children suffered from DDE, with second primary molars as the most affected teeth and demarcated opacities as the most prevalent type of defect. Preterm birth and hospitalisation in first year of life can be considered as risk factors for DDE in the primary dentition. German Clinical Trials Register, DRKS00003438.

  11. GNAS defects identified by stimulatory G protein alpha-subunit signalling studies in platelets.

    PubMed

    Freson, Kathleen; Izzi, Benedetta; Labarque, Veerle; Van Helvoirt, Monique; Thys, Chantal; Wittevrongel, Christine; Bex, Marie; Bouillon, Roger; Godefroid, Nathalie; Proesmans, Willem; de Zegher, Francis; Jaeken, Jaak; Van Geet, Chris

    2008-12-01

    GNAS is an imprinted region that gives rise to several transcripts, antisense transcripts, and noncoding RNAs, including transcription of RNA encoding the alpha-subunit of the stimulatory G protein (Gsalpha). The complexity of the GNAS cluster results in ubiquitous genomic imprints, tissue-specific Gsalpha expression, and multiple genotype-phenotype relationships. Phenotypes resulting from genetic and epigenetic abnormalities of the GNAS region include Albright's hereditary osteodystrophy, pseudohypoparathyroidism types Ia (PHPIa) and Ib (PHPIb), and pseudopseudohypoparathyroidism (PPHP). The aim was to study the complex GNAS pathology by a functional test as an alternative to the generally used but labor-intensive erythrocyte complementation assay. We report the first platelet-based diagnostic test for Gsalpha hypofunction, supported by clinical, biochemical, and molecular data for six patients with PHPIa or PPHP and nine patients with PHPIb. The platelet test is based on the inhibition of platelet aggregation by cAMP, produced after Gsalpha stimulation. Platelets are easily accessible, and platelet aggregation responses were found to reflect Gsalpha signaling defects in patients, in concordance with the patient's phenotype and genotype. Gsalpha hypofunction in PHPIa and PPHP patients with GNAS mutations was clearly detected by this method. Mildly decreased or normal Gsalpha function was detected in patients with PHPIb with either an overall or exon 1A-only epigenetic defect, respectively. Platelet Gsalpha expression was reduced in both PHPIb patient groups, whereas XLalphas was up-regulated only in PHPIb patients with the broad epigenetic defect. The platelet-based test is a novel tool for establishing the diagnosis of Gsalpha defects, which may otherwise be quite challenging.

  12. Defects in a-Si and a-Si:H: A numerical study

    NASA Astrophysics Data System (ADS)

    Knief, Simone; von Niessen, Wolfgang; Koslowski, Thorsten

    1998-08-01

    We present a numerical study of the electronic properties of various structural models of amorphous silicon and hydrogenated amorphous silicon. Starting from an ideal random network, dangling bonds, floating bonds, double bonds, microvoids, hydrogenated dangling bonds, and hydrogenated floating bonds are introduced. The concentrations of these defects can be varied independently, the amount of disorder introduced to the system is therefore strictly controllable. Two continuous random networks, the vacancy model of Duffy, Boudreaux, and Polk and the bond switching model of Wooten, Winer, and Weaire (WWW model) are investigated. For the relaxation of the structures the potentials of Keating and of Stillinger and Weber are employed. The electronic structure is described by a tight-binding Hamiltonian; the localized or extended character of the eigenstates is investigated via a scaling approach. The vacancy model shows a band gap for small defect concentrations but this fills up with increasing disorder. Similar behavior is found for the case of the other models. In general defects introduce states into the gap region of a-Si, where the dangling bonds lead to the largest density of states in the gap region for a given defect concentration. This model turns out to be unique. For small system sizes an impurity band results that dramatically changes its character for large systems above 4000 atoms to a nearly uniform density of states as observed experimentally. In a-Si:H the dangling and floating bonds are removed and a mobility gap results with a width in good agreement with experiment. The experimentally observed tailing of the band into the gap region (first linear, then exponential) is well described only for the a-Si:H model derived from the vacancy model and for very large system sizes above 4000 atoms. The WWW model does not lead to this tail behavior. Localized states are found at all band edges but states at the bottom of the conduction band are more strongly

  13. A study of the mechanism of laser welding defects in low thermal expansion superalloy GH909

    SciTech Connect

    Yan, Fei; Wang, Chunming Wang, Yajun; Hu, Xiyuan; Wang, Tianjiao; Li, Jianmin; Li, Guozhu

    2013-04-15

    In this paper, we describe experimental laser welding of low-thermal-expansion superalloy GH909. The main welding defects of GH909 by laser in the weld are liquation cracks and porosities, including hydrogen and carbon monoxide porosity. The forming mechanism of laser welding defects was investigated. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum, X-ray diffractometer and other methodologies. The results demonstrated that porosities appearing in the central weld were related to incomplete removal of oxide film on the surface of the welding samples. The porosities produced by these bubbles were formed as a result of residual hydrogen or oxygenium in the weld. These elements failed to escape from the weld since laser welding has both a rapid welding speed and cooling rate. The emerging crack in the heat affected zone is a liquation crack and extends along the grain boundary as a result of composition segregation. Laves–Ni{sub 2}Ti phase with low melting point is a harmful phase, and the stress causes grain boundaries to liquefy, migrate and even crack. Removing the oxides on the surface of the samples before welding and carefully controlling technological parameters can reduce welding defects and improve formation of the GH909 alloy weld. - Highlights: ► It is a new process for the forming of GH909 alloy via laser welding. ► The forming mechanism of laser welding defects in GH909 has been studied. ► It may be a means to improve the efficiency of aircraft engine production.

  14. Study on the Microwave Transmission Characteristics of a Three-Dimensional Electromagnetic Bandgap Structure with Coupled Defects

    NASA Astrophysics Data System (ADS)

    Chen, Shibin; Li, Dichen; Tian, Xiaoyong; Han, Haoxue; Wu, Haihua

    2012-03-01

    The influence of a vertical coupled defect on the localized properties of a diamond electromagnetic bandgap (EBG) structure has been studied in the present research. The diamond EBG structure with a cavity defect was fabricated by stereolithography and gel-casting processes with alumina slurry. The resonant peaks of two kinds of defects were compared by measuring their microwave transmission characteristics using a network analyzer. A higher quality factor ( Q) was obtained for the diamond EBG structure with a vertical coupled defect, and the transmission efficiency of resonant peak was improved by 29.6% in comparison with a single defect. Experimental results agreed with the simulation results. These microwave transmission characteristics of the three-dimensional (3D) EBG structures indicate that they can be applied in microwave devices to improve transmission efficiency.

  15. Structures and Energetics of Defects: A Comparative Study of 3C- and 4H-SiC

    SciTech Connect

    Gao, Fei; Posselt, Matthias; Belko, V; Zhang, Yanwen; Weber, William J.

    2004-05-01

    The structures, formation energies and stable configurations of elementary defects (vacancies, antisite defects and self interstitials) in 3C- and 4H-SiC are studied using classical molecular dynamics simulation with a recently developed interatomic potential. The defect structures in 3C-SiC are relatively simple, but those in 4H-SiC are more complicated. The interstitials between hexagonal and trigonal rings are characteristic for 4H-SiC and other hexagonal polytypes, but not for 3C-SiC. The number of non-equivalent defects in 4H-SiC is much higher than that in 3C-SiC, and a considerable difference is found for some complex and anisotropic defects, in particular for the dumbbells D1Si-Si, D1Si-C and D2Si-C. The lattice deformation beyond the first nearest neighbor shell, which depends strongly on the polytype structure, plays an important role on these effects. However, the polytypism does not have a significant influence on the structure and energetics of the more compact and isotropic defects, such as vacancies and antisite defects. Despite the complexity of defect configurations, the tetrahedral interstitials have very similar properties in 3C- and 4H-SiC because their first, second and third nearest neighbor shells are identical.

  16. A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions

    DOE PAGES

    Samanta, Amit

    2016-02-19

    Using first principles density functional theory calculations, we present a study of the structure, mobility, and the thermodynamic stability of anionic defects in the high-temperature cubic phase of ZrO2. Our results suggest that the local structure of an oxygen interstitial depends on the charge state and the cubic symmetry of the anionic sublattice is unstable at 0 K. In addition, the oxygen interstitials and the vacancies exhibit symmetry breaking transitions to low-energy structures with tetragonal distortion of the oxygen sublattice at 0 K. However, the vibrational entropy stabilizes the defect structures with cubic symmetry at 2600–2980 K. The formation freemore » energies of the anionic defects and Gibbs free energy changes associated with different defect reactions are calculated by including the vibrational free energy contributions and the effect of pressure on these defect structures. By analyzing the defect chemistry, we obtain the defect concentrations at finite temperature and pressure conditions using the zero temperature ab initio results as input and find that at low oxygen partial pressures, neutral oxygen vacancies are most dominant and at high oxygen partial pressures, doubly charged anionic defects are dominant. As a result, the relevance of the results to the thermal protective coating capabilities of zirconium-based ceramic composites is elucidated.« less

  17. A theoretical study of the stability of anionic defects in cubic ZrO2 at extreme conditions

    SciTech Connect

    Samanta, Amit

    2016-02-19

    Using first principles density functional theory calculations, we present a study of the structure, mobility, and the thermodynamic stability of anionic defects in the high-temperature cubic phase of ZrO2. Our results suggest that the local structure of an oxygen interstitial depends on the charge state and the cubic symmetry of the anionic sublattice is unstable at 0 K. In addition, the oxygen interstitials and the vacancies exhibit symmetry breaking transitions to low-energy structures with tetragonal distortion of the oxygen sublattice at 0 K. However, the vibrational entropy stabilizes the defect structures with cubic symmetry at 2600–2980 K. The formation free energies of the anionic defects and Gibbs free energy changes associated with different defect reactions are calculated by including the vibrational free energy contributions and the effect of pressure on these defect structures. By analyzing the defect chemistry, we obtain the defect concentrations at finite temperature and pressure conditions using the zero temperature ab initio results as input and find that at low oxygen partial pressures, neutral oxygen vacancies are most dominant and at high oxygen partial pressures, doubly charged anionic defects are dominant. As a result, the relevance of the results to the thermal protective coating capabilities of zirconium-based ceramic composites is elucidated.

  18. Assessment of the LED phototherapy on femoral bone defects of ovariectomized rats: a Raman spectral study.

    PubMed

    Aciole, Jouber Mateus dos Santos; de Castro, Isabele Cardoso Vieira; Soares, Luiz Guilherme Pinheiro; Barbosa, Artur Felipe Santos; Aciole, Gilberth Tadeu dos Santos; Silveira, Landulfo; Pinheiro, Antonio L B

    2014-05-01

    Osteoporosis is a disease characterized by the reduction of bone mineral density. LED wavelengths seem to have similar photo-stimulating effects to laser light. The aim of this study was to assess the Raman shifts: ∼ 960 (phosphate hydroxyapatite), ∼ 1,070 (carbonate hydroxyapatite), and ∼ 1,454 cm (-1) (lipids and proteins) on bone defects of ovariectomized rats treated or not with LED phototherapy (LED-PT). Thirty female rats were divided into four groups (Basal, OVX, OVX+Clot, and OVX+Clot+LED), then subdivided into two subgroups (15 and 30 days after surgery). Osteoporosis induction by ovariectomy (OVX) was performed in all groups, except for the normal basal group. Following development of osteoporosis, one surgical bone defect (5 mm(2)) was created on the femur of each animal. Defects were irradiated with LED light (λ = 850 ± 10 nm, P = 150 mW, CW, Ф = 0.5 cm(2), 20.4 J/cm(2) per session, t = 128 s, 163.2 J/cm(2) per treatment) at 48 h interval during 2 weeks. Raman measurements were taken at the surface of the defects 30 days after surgery. Significant difference between groups Basal, OVX+Clot, and OVX+Clot+LED for the peaks at ∼ 960 (p ≤ 0.001; 15 and 30 days), ∼ 1,070 (p ≤ 0.001; 15 and 30 days), and ∼ 1,450 cm(-1) (p = 0.002; 15 days; p = 0.004; 30 days) were detected. In addition, statistical differences were obtained between groups OVX, OVX+Clot, and OVX+Clot+LED for these same peaks at all time points (p ≤ 0.001). At 15 and 30 days, there were statistical differences between groups OVX+Clot and OVX+Clot+LED for the peaks at ∼ 960 (p ≤ 0.001), ∼ 1,070 (p ≤ 0.001; p = 0.003), and ∼ 1,450 cm(-1) (p ≤ 0.001; p = 0.002). The results of this study are indicative that infrared LED-PT improved the deposition of HA on bone defects of ovariectomized rats.

  19. A Study on Substance Abuse Prevention

    ERIC Educational Resources Information Center

    Seçim, Gürcan

    2017-01-01

    This study aims to examine options to increase the supportive power of parents, teachers, school administrators, and counselors who directly interact with children and adolescents and have a fundamental responsibility to protect them from the risks of substance abuse and evaluate the effectiveness of associated training programs. The study design…

  20. Induction of fully stabilized cortical bone defects to study intramembranous bone regeneration

    PubMed Central

    McGee-Lawrence, Meghan E.; Razidlo, David F.

    2015-01-01

    Summary Bone is a regenerative tissue with an innate ability to self-remodel in response to environmental stimuli and the need to repair damage. Rodent models of fracture healing, and in particular genetic mouse models, can be used to study the contributions of specific molecular switches to skeletal repair, as well as to recreate and exacerbate biological development and repair mechanisms in postnatal skeletons. Here, we describe methodology for producing fully stabilized, single-cortex defects in mouse femurs to study mechanisms of intramembranous bone regeneration. PMID:25331051

  1. A Pilot Study of Emollient Therapy for the Primary Prevention of Atopic Dermatitis

    PubMed Central

    Simpson, Eric L.; Berry, Trista M.; Brown, Peter A.; Hanifin, Jon M.

    2011-01-01

    Background Prevention strategies in atopic dermatitis (AD) using allergen avoidance have not been consistently effective. New research reveals the importance of the skin barrier in the development of AD and possibly food allergy and asthma. Correcting skin barrier defects from birth may prevent AD onset or moderate disease severity. Objective We sought to determine the feasibility of skin barrier protection as a novel AD prevention strategy. Methods We enrolled 22 neonates at high risk for developing AD in a feasibility pilot study using emollient therapy from birth. Results No intervention-related adverse events occurred in our cohort followed up for a mean time of 547 days. Of the 20 subjects who remained in the study, 3 (15.0%) developed AD, suggesting a protective effect when compared with historical controls. Skin barrier measurements remained within ranges seen in normal-appearing skin. Limitations No conclusions regarding efficacy can be made without a control group. Conclusions Skin barrier repair from birth represents a novel and feasible approach to AD prevention. Further studies are warranted to determine the efficacy of this approach. PMID:20692725

  2. A pilot study of emollient therapy for the primary prevention of atopic dermatitis.

    PubMed

    Simpson, Eric L; Berry, Trista M; Brown, Peter A; Hanifin, Jon M

    2010-10-01

    Prevention strategies in atopic dermatitis (AD) using allergen avoidance have not been consistently effective. New research reveals the importance of the skin barrier in the development of AD and possibly food allergy and asthma. Correcting skin barrier defects from birth may prevent AD onset or moderate disease severity. We sought to determine the feasibility of skin barrier protection as a novel AD prevention strategy. We enrolled 22 neonates at high risk for developing AD in a feasibility pilot study using emollient therapy from birth. No intervention-related adverse events occurred in our cohort followed up for a mean time of 547 days. Of the 20 subjects who remained in the study, 3 (15.0%) developed AD, suggesting a protective effect when compared with historical controls. Skin barrier measurements remained within ranges seen in normal-appearing skin. No conclusions regarding efficacy can be made without a control group. Skin barrier repair from birth represents a novel and feasible approach to AD prevention. Further studies are warranted to determine the efficacy of this approach. Copyright © 2009 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  3. Maternal dietary intake of nitrates, nitrites and nitrosamines and selected birth defects in offspring: a case-control study.

    PubMed

    Huber, John C; Brender, Jean D; Zheng, Qi; Sharkey, Joseph R; Vuong, Ann M; Shinde, Mayura U; Griesenbeck, John S; Suarez, Lucina; Langlois, Peter H; Canfield, Mark A; Romitti, Paul A; Weyer, Peter J

    2013-03-21

    Dietary intake of nitrates, nitrites, and nitrosamines can increase the endogenous formation of N-nitroso compounds in the stomach. Results from animal studies suggest that these compounds might be teratogenic. We examined the relationship between maternal dietary intake of nitrates, nitrites (including plant and animal sources as separate groups), and nitrosamines and several types of birth defects in offspring. For this population-based case-control study, data from a 58-question food frequency questionnaire, adapted from the short Willett Food Frequency Questionnaire and administered as part of the National Birth Defects Prevention Study (NBDPS), were used to estimate daily intake of dietary nitrates, nitrites, and nitrosamines in a sample of 6544 mothers of infants with neural tube defects (NTD)s, oral clefts (OC)s, or limb deficiencies (LD)s and 6807 mothers of unaffected control infants. Total daily intake of these compounds was divided into quartiles based on the control mother distributions. Odds ratios (OR)s and 95% confidence intervals (CI)s were estimated using logistic regression; estimates were adjusted for maternal daily caloric intake, maternal race-ethnicity, education, dietary folate intake, high fat diet (>30% of calories from fat), and state of residence. While some unadjusted ORs for NTDS had 95% (CI)s that excluded the null value, none remained significant after adjustment for covariates, and the effect sizes were small (adjusted odds ratios [aOR]<1.12). Similar results were found for OCs and LDs with the exception of animal nitrites and cleft lip with/without cleft palate (aORs and CIs for quartile 4 compared to quartile 1 =1.24; CI=1.05-1.48), animal nitrites and cleft lip (4th quartile aOR=1.32; CI=1.01-1.72), and total nitrite and intercalary LD (4th quartile aOR=4.70; CI=1.23-17.93). Overall, odds of NTDs, OCs or LDs did not appear to be significantly associated with estimated dietary intake of nitrate, nitrite, and nitrosamines.

  4. Nutri-epigenomic Studies Related to Neural Tube Defects: Does Folate Affect Neural Tube Closure Via Changes in DNA Methylation?

    PubMed

    Rochtus, Anne; Jansen, Katrien; Van Geet, Chris; Freson, Kathleen

    2015-01-01

    Neural tube defects (NTDs), affecting 1-2 per 1000 pregnancies, are severe congenital malformations that arise from the failure of neurulation during early embryonic development. The methylation hypothesis suggests that folate prevents NTDs by stimulating cellular methylation reactions. Folate is central to the one-carbon metabolism that produces pyrimidines and purines for DNA synthesis and for the generation of the methyldonor S-adenosyl-methionine. This review focuses on the relation between the folate-mediated one-carbon metabolism, DNA methylation and NTDs. Studies will be discussed that investigated global or locus-specific DNA methylation differences in patients with NTDs. Folate deficiency may increase NTD risk by decreasing DNA methylation, but to date, human studies vary widely in study design in terms of analyzing different clinical subtypes of NTDs, using different methylation quantification assays and using DNA isolated from diverse types of tissues. Some studies have focused mainly on global DNA methylation differences while others have quantified specific methylation differences for imprinted genes, transposable elements and DNA repair enzymes. Findings of global DNA hypomethylation and LINE-1 hypomethylation suggest that epigenetic alterations may disrupt neural tube closure. However, current research does not support a linear relation between red blood cell folate concentration and DNA methylation. Further studies are required to better understand the interaction between folate, DNA methylation changes and NTDs.

  5. Nutritional and genetic determinants of vitamin B and homocysteine metabolisms in neural tube defects: a multicenter case-control study.

    PubMed

    Candito, Mirande; Rivet, Romain; Herbeth, Bernard; Boisson, Catherine; Rudigoz, René-Charles; Luton, Dominique; Journel, Hubert; Oury, Jean-François; Roux, François; Saura, Robert; Vernhet, Isabelle; Gaucherand, Pascal; Muller, Françoise; Guidicelli, Béatrice; Heckenroth, Hélène; Poulain, Patrice; Blayau, Martine; Francannet, Christine; Roszyk, Laurence; Brustié, Cécile; Staccini, Pascal; Gérard, Philippe; Fillion-Emery, Nathalie; Guéant-Rodriguez, Rosa-Maria; Van Obberghen, Emmanuel; Guéant, Jean-Louis

    2008-05-01

    Neural tube defects (NTDs) are severe congenital malformations due to failure of neural tube formation in early pregnancy. The proof that folic acid prevents NTDs raises the question of whether other parts of homocysteine (Hcy) metabolism may affect rates of NTDs. This French case-control study covered: 77 women aged 17-42 years sampled prior to elective abortion for a severe NTDs (cases) and 61 women aged 20-43 years with a normal pregnancy. Plasma and erythrocyte folate, plasma B6, B12 and Hcy were tested as five polymorphisms MTHFR 677 C --> T, MTHFR 1298 A --> C, MTR 2756 A --> G, MTTR 66 A --> G and TCN2 776 C --> G. Cases had significantly lower erythrocyte folate, plasma folate, B12 and B6 concentrations than the controls, and higher Hcy concentration. The odds ratio was 2.15 (95% CI: 1.00-4.59) for women with the MTRR 66 A --> G allele and it was decreased for mothers carrying the MTHFR 1298 A --> C allele. In multivariate analysis, only the erythrocyte folate concentration (P = 0.005) and plasma B6 concentration (P = 0.020) were predictors. Red cell folate is the main determinant of NTDs in France. Folic acid supplement or flour fortification would prevent most cases. Increased consumption of vitamins B12 and B6 could contribute to the prevention of NTDs. Genetic polymorphisms played only a small role. Until folic acid fortification becomes mandatory, all women of reproductive age should consume folic acid in a multivitamin that also contains B12 and B6.

  6. Assessment of visual space recognition in patients with visual field defects using head mounted display (HMD) system: case study with severe visual field defect.

    PubMed

    Sugihara, Shunichi; Tanaka, Toshiaki; Miyasaka, Tomoya; Izumi, Takashi; Shimizu, Koichi

    2013-01-01

    For the quantitative assessment of visual field defects of cerebrovascular patients, we developed a new measurement system that could present various kinds of visual information to the patient. In this system, we use a head mounted display as the display device. The quantitative assessment becomes possible by adding the capability to measure the eye movement and the head movement simultaneously by means of a video apparatus of motion analysis. In our study, we examined the effectiveness of this system by applying it to a patient with serious visual field defects. The visual image of the reduced test paper was presented to the patient, the effect on his/her spatial recognition and eye movement was investigated. The results indicated the increase in the ration of visual search in the reduced side. With the reduced image, the decrease of the angular velocity of eye movement was recognized in the visual search in the defected side. In the motion analysis, the head movement was not observed while the eye movements appeared corresponding to each different conditions. This fact led us to confirm that the patient coped with this kind of test by the eye movement. In this analysis, the effectiveness and the usefulness of the developed system were confirmed that enables us to evaluate the abnormal and compensation movement of the eyes.

  7. Core-level photoabsorption study of defects and metastable bonding configurations in boron nitride

    SciTech Connect

    Jimenez, I.; Jankowski, A.F.; Terminello, L.J.

    1997-04-01

    Boron nitride is an interesting material for technological applications and for fundamental solid state physics investigations. It is a compound isoelectronic with carbon and, like carbon can possess sp{sup 2} and sp{sup 3} bonded phases resembling graphite and diamond. BN crystallizes in the sp{sup 2}-bonded hexagonal (h-BN), rhombohedral (r-BN) and turbostratic phases, and in the sp{sup 3}-bonded cubic (c-BN) and wurtzite (w-BN) phases. A new family of materials is obtained when replacing C-C pairs in graphite with isoelectronic B-N pairs, resulting in C{sub 2}BN compounds. Regarding other boron compounds, BN is exceptional in the sense that it has standard two-center bonds with conventional coordination numbers, while other boron compounds (e.g. B{sub 4}C) are based on the boron icosahedron unit with three-center bonds and high coordination numbers. The existence of several allotropic forms and fullerene-like structures for BN suggests a rich variety of local bonding and poses the questions of how this affects the local electronic structure and how the material accommodates the stress induced in the transition regions between different phases. One would expect point defects to play a crucial role in stress accommodation, but these must also have a strong influence in the electronic structure, since the B-N bond is polar and a point defect will thus be a charged structure. The study of point defects in relationship to the electronic structure is of fundamental interest in these materials. Recently, the authors have shown that Near-Edge X-ray Absorption Fine Structure (NEXAFS) is sensitive to point defects in h-BN, and to the formation of metastable phases even in amorphous materials. This is significant since other phase identification techniques like vibrational spectroscopies or x-ray diffraction yield ambiguous results for nanocrystalline and amorphous samples. Serendipitously, NEXAFS also combines chemical selectivity with point defect sensitivity.

  8. Defective Kernel Mutants of Maize II. Morphological and Embryo Culture Studies.

    PubMed

    Sheridan, W F; Neuffer, M G

    1980-08-01

    This report presents the initial results of our study of the immature kernel stage of 150 defective kernel maize mutants. They are single gene, recessive mutants that map throughout the genome, defective in both endosperm and embryo development and, for the most part, lethal (Neuffer and Sheridan 1980). All can be distinguished on immature ears, and 85% of them reveal a mutant phenotype within 11 to 17 days post-pollination. Most have immature kernels that are smaller and lighter in color than their normal counterparts. Forty of the mutants suffer from their defects early in kernel development and are blocked in embryogenesis before their primordia differentiate, or, if primordia are formed, they are unable to germinate when cultured as immature embryos or tested at maturity; a few begin embryo degeneration prior to the time that mutant kernels became visually distinguishable. The others express the associated lesion later in kernel development and form at least one leaf primordium by the time kernels are distinguishable and will germinate when cultured or tested at maturity. In most cases, on a fresh weight basis, the mutants have embryos that are more severely defective than the endosperm; their embryos usually are no more than one-half to two-thirds the size, and lag behind by one or two developmental stages. in comparison with embryos in normal kernels from the same ear. One hundred and two mutants were examined by culturing embryos on basal and enriched media; 21 simply enlarged or completely failed to grow on any of the media tested; and 81 produced shoots and roots on at least one medium. Many grew equally well on basal and enriched media; 16 grew at a faster rate on basal medium and 23 displayed a superior growth on enriched medium. Among the latter group, 10 may be auxotrophs. One of these mutants and another mutant isolated by E. H. Coe are proline-requiring mutants, allelic to pro-1. Considering their diversity of expression as evidenced by their

  9. Defective Kernel Mutants of Maize II. Morphological and Embryo Culture