Apparent prevention of neural tube defects by periconceptional vitamin supplementation.

PubMed Central

Smithells, R W; Sheppard, S; Schorah, C J; Seller, M J; Nevin, N C; Harris, R; Read, A P; Fielding, D W

1981-01-01

An earlier preliminary paper is expanded. Women who had given birth to one or more infants with a neural tube defect were recruited into a trial of per conceptional vitamin supplementation. Two hundred mothers attending five centres were fully supplemented (FS), 50 were partially supplemented (PS), and 300 were unsupplemented (US). Neural tube defect recurrences in the study pregnancies were 1 (0.5%), in FS, none in PS, and 13 (4%) in US mothers. The difference in outcome between FS and US mothers is significant. The most likely explanation is that supplementation has prevented some neural tube defects, but further studies are needed. PMID:7332338

Maternal report of fever from cold or flu during early pregnancy and the risk for noncardiac birth defects, National Birth Defects Prevention Study, 1997-2011.

PubMed

Waller, Dorothy Kim; Hashmi, Syed Shahrukh; Hoyt, Adrienne T; Duong, Hao T; Tinker, Sarah C; Gallaway, Michael Shayne; Olney, Richard S; Finnell, Richard H; Hecht, Jacqueline Tauber; Canfield, Mark A

2018-03-01

As maternal fever affects approximately 6-8% of early pregnancies, it is important to expand upon previous observations of an association between maternal fever and birth defects. We analyzed data from the National Birth Defects Prevention Study, a multistate, case-control study of major structural birth defects. Telephone interviews were completed by mothers of cases (n = 17,162) and controls (n = 10,127). Using multivariable logistic regression, we assessed the association between maternal self-report of cold or flu with fever and cold or flu without fever during early pregnancy and 30 categories of non-cardiac birth defects. Maternal report of cold or flu with fever was significantly associated with 8 birth defects (anencephaly, spina bifida, encephalocele, cleft lip with or without cleft palate, colonic atresia/stenosis, bilateral renal agenesis/hypoplasia, limb reduction defects, and gastroschisis) with elevated adjusted odds ratios ranging from 1.2 to 3.7. Maternal report of cold or flu without fever was not associated with any of the birth defects studied. This study adds to the evidence that maternal fever during early pregnancy is associated with an increased risk for selected birth defects. Elevated associations were limited to mothers who reported a fever, suggesting that it is fever that contributes to the excess risk rather than illnesses associated with it. However, fever may also serve as a marker for more severe infections. © 2017 Wiley Periodicals, Inc.

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.

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

[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.

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.

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.

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.

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

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…

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

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

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

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

Using bayesian models to assess the effects of under-reporting of cannabis use on the association with birth defects, national birth defects prevention study, 1997-2005.

PubMed

van Gelder, Marleen M H J; Donders, A Rogier T; Devine, Owen; Roeleveld, Nel; Reefhuis, Jennita

2014-09-01

Studies on associations between periconceptional cannabis exposure and birth defects have mainly relied on self-reported exposure. Therefore, the results may be biased due to under-reporting of the exposure. The aim of this study was to quantify the potential effects of this form of exposure misclassification. Using multivariable logistic regression, we re-analysed associations between periconceptional cannabis use and 20 specific birth defects using data from the National Birth Defects Prevention Study from 1997-2005 for 13 859 case infants and 6556 control infants. For seven birth defects, we implemented four Bayesian models based on various assumptions concerning the sensitivity of self-reported cannabis use to estimate odds ratios (ORs), adjusted for confounding and under-reporting of the exposure. We used information on sensitivity of self-reported cannabis use from the literature for prior assumptions. The results unadjusted for under-reporting of the exposure showed an association between cannabis use and anencephaly (posterior OR 1.9 [95% credible interval (CRI) 1.1, 3.2]) which persisted after adjustment for potential exposure misclassification. Initially, no statistically significant associations were observed between cannabis use and the other birth defect categories studied. Although adjustment for under-reporting did not notably change these effect estimates, cannabis use was associated with esophageal atresia (posterior OR 1.7 [95% CRI 1.0, 2.9]), diaphragmatic hernia (posterior OR 1.8 [95% CRI 1.1, 3.0]), and gastroschisis (posterior OR 1.7 [95% CRI 1.2, 2.3]) after correction for exposure misclassification. Under-reporting of the exposure may have obscured some cannabis-birth defect associations in previous studies. However, the resulting bias is likely to be limited. © 2014 John Wiley & Sons Ltd.

Using Bayesian Models to Assess the Effects of Under-reporting of Cannabis Use on the Association with Birth Defects, National Birth Defects Prevention Study, 1997–2005

PubMed Central

van Gelder, Marleen M. H. J.; Rogier, A.; Donders, T.; Devine, Owen; Roeleveld, Nel; Reefhuis, Jennita

2015-01-01

Background Studies on associations between periconceptional cannabis exposure and birth defects have mainly relied on self-reported exposure. Therefore, the results may be biased due to underreporting of the exposure. The aim of this study was to quantify the potential effects of this form of exposure misclassification. Methods Using multivariable logistic regression, we re-analyzed associations between periconceptional cannabis use and 20 specific birth defects using data from the National Birth Defects Prevention Study from 1997–2005 for 13 859 case infants and 6556 control infants. For seven birth defects, we implemented four Bayesian models based on various assumptions concerning the sensitivity of self-reported cannabis use to estimate odds ratios (ORs), adjusted for confounding and underreporting of the exposure. We used information on sensitivity of self-reported cannabis use from the literature for prior assumptions. Results The results unadjusted for underreporting of the exposure showed an association between cannabis use and anencephaly (posterior OR 1.9 [95% credible interval (CRI) 1.1, 3.2]) which persisted after adjustment for potential exposure misclassification. Initially, no statistically significant associations were observed between cannabis use and the other birth defect categories studied. Although adjustment for underreporting did not notably change these effect estimates, cannabis use was associated with esophageal atresia (posterior OR 1.7 [95% CRI 1.0, 2.9]), diaphragmatic hernia (posterior OR 1.8 [95% CRI 1.1, 3.0]) and gastroschisis (posterior OR 1.7 [95% CRI 1.2, 2.3]) after correction for exposure misclassification. Conclusions Underreporting of the exposure may have obscured some cannabis-birth defect associations in previous studies. However, the resulting bias is likely to be limited. PMID:25155701

Fostering International Collaboration in Birth Defects Research and Prevention: A Perspective From the International Clearinghouse for Birth Defects Surveillance and Research

PubMed Central

Botto, Lorenzo D.; Robert-Gnansia, Elisabeth; Siffel, Csaba; Harris, John; Borman, Barry; Mastroiacovo, Pierpaolo

2006-01-01

The International Clearing-house for Birth Defects Surveillance and Research, formerly known as International Clearinghouse of Birth Defects Monitoring Systems, consists of 40 registries worldwide that collaborate in monitoring 40 types of birth defects. Clearinghouse activities include the sharing and joint monitoring of birth defect data, epidemiologic and public health research, and capacity building, with the goal of reducing disease and promoting healthy birth outcomes through primary prevention. We discuss 3 of these activities: the collaborative assessment of the potential teratogenicity of first-trimester use of medications (the MADRE project), an example of the intersection of surveillance and research; the international databases of people with orofacial clefts, an example of the evolution from surveillance to outcome research; and the study of genetic polymorphisms, an example of collaboration in public health genetics. PMID:16571708

Inositol for prevention of neural tube defects: a pilot randomised controlled trial - CORRIGENDUM

PubMed Central

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

2016-01-01

Although peri-conceptional folic acid (FA) supplementation can prevent a proportion of neural tube defects (NTDs), there is increasing evidence that many NTDs are FA non-responsive. The vitamin-like molecule inositol may offer a novel approach to preventing FA-non-responsive NTDs. Inositol prevented NTDs 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-four further pregnancies were documented. Two NTDs 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. PMID:26917444

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.

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.

Preventing neural tube defects in Europe: a missed opportunity.

PubMed

Busby, Araceli; Abramsky, Lenore; Dolk, Helen; Armstrong, Ben; Addor, Marie-Claude; Anneren, Goran; Armstrong, Nicola; Baguette, Andre; Barisic, Ingeborg; Berghold, Andrea; Bianca, Sebastiano; Braz, Paula; Calzolari, Elisa; Christiansen, Marianne; Cocchi, Guido; Daltveit, Anne Kjersti; De Walle, Hermien; Edwards, Grace; Gatt, Miriam; Gener, Blanca; Gillerot, Yves; Gjergja, Romana; Goujard, Janine; Haeusler, Martin; Latos-Bielenska, Anna; McDonnell, Robert; Neville, Amanda; Olars, Birgitta; Portillo, Isabel; Ritvanen, Annukka; Robert-Gnansia, Elizabeth; Rösch, Christine; Scarano, Gioacchino; Steinbicker, Volker

2005-01-01

Each year, more than 4500 pregnancies in the European Union are affected by neural tube defects (NTD). Unambiguous evidence of the effectiveness of periconceptional folic acid in preventing the majority of neural tube defects has been available since 1991. We report on trends in the total prevalence of neural tube defects up to 2002, in the context of a survey in 18 European countries of periconceptional folic acid supplementation (PFAS) policies and their implementation. EUROCAT is a network of population-based registries in Europe collaborating in the epidemiological surveillance of congenital anomalies. Representatives from 18 participating countries provided information about policy, health education campaigns and surveys of PFAS uptake. The yearly total prevalence of neural tube defects including livebirths, stillbirths and terminations of pregnancy was calculated from 1980 to 2002 for 34 registries, with UK and Ireland estimated separately from the rest of Europe. A meta-analysis of changes in NTD total prevalence between 1989-1991 and 2000-2002 according to PFAS policy was undertaken for 24 registries. By 2005, 13 countries had a government recommendation that women planning a pregnancy should take 0.4mg folic acid supplement daily, accompanied in 7 countries by government-led health education initiatives. In the UK and Ireland, countries with PFAS policy, there was a 30% decline in NTD total prevalence (95% CI 16-42%) but it was difficult to distinguish this from the pre-existing strong decline. In other European countries with PFAS policy, there was virtually no decline in NTD total prevalence whether a policy was in place by 1999 (2%, 95% CI 28% reduction to 32% increase) or not (8%, 95% CI 26% reduction to 16% increase). The potential for preventing NTDs by periconceptional folic acid supplementation is still far from being fulfilled in Europe. Only a public health policy including folic acid fortification of staple foods is likely to result in large

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

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

Impact of time to maternal interview on interview responses in the National Birth Defects Prevention Study.

PubMed

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

2013-06-01

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.

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.

Maternal occupational exposure to polycyclic aromatic hydrocarbons and craniosynostosis among offspring in the National Birth Defects Prevention Study.

PubMed

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

2016-01-01

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. We used data from craniosynostosis cases and control infants in the National Birth Defects Prevention Study (NBDPS) with estimated delivery dates from 1997 to 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 1 month before conception through delivery. We used logistic regression to assess the association between occupational exposure to PAHs and craniosynostosis. 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 1 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. 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. © 2015 Wiley Periodicals, Inc.

Impact of sample collection participation on the validity of estimated measures of association in the National Birth Defects Prevention Study when assessing gene-environment interactions.

PubMed

Jenkins, Mary M; Reefhuis, Jennita; Herring, Amy H; Honein, Margaret A

2017-12-01

To better understand the impact that nonresponse for specimen collection has on the validity of estimates of association, we examined associations between self-reported maternal periconceptional smoking, folic acid use, or pregestational diabetes mellitus and six birth defects among families who did and did not submit buccal cell samples for DNA following a telephone interview as part of the National Birth Defects Prevention Study (NBDPS). Analyses included control families with live born infants who had no birth defects (N = 9,465), families of infants with anorectal atresia or stenosis (N = 873), limb reduction defects (N = 1,037), gastroschisis (N = 1,090), neural tube defects (N = 1,764), orofacial clefts (N = 3,836), or septal heart defects (N = 4,157). Estimated dates of delivery were between 1997 and 2009. For each exposure and birth defect, odds ratios and 95% confidence intervals were calculated using logistic regression stratified by race-ethnicity and sample collection status. Tests for interaction were applied to identify potential differences between estimated measures of association based on sample collection status. Significant differences in estimated measures of association were observed in only four of 48 analyses with sufficient sample sizes. Despite lower than desired participation rates in buccal cell sample collection, this validation provides some reassurance that the estimates obtained for sample collectors and noncollectors are comparable. These findings support the validity of observed associations in gene-environment interaction studies for the selected exposures and birth defects among NBDPS participants who submitted DNA samples. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

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.

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

Various Stone-Wales defects in phagraphene

NASA Astrophysics Data System (ADS)

Openov, L. A.; Podlivaev, A. I.

2016-08-01

Various Stone-Wales defects in phagraphene, which is a graphene allotrope, predicted recently are studied in terms of the nonorthogonal tight-binding model. The energies of the defect formation and the heights of energy barriers preventing the formation and annealing of the defects are found. Corresponding frequency factors in the Arrhenius formula are calculated. The evolution of the defect structure is studied in the real-time mode using the molecular dynamics method.

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

Preconceptional folic acid-containing supplement use in the National Birth Defects Prevention Study.

PubMed

Khodr, Zeina G; Lupo, Philip J; Agopian, A J; Canfield, Mark A; Case, Amy P; Carmichael, Suzan L; Mitchell, Laura E

2014-06-01

Despite public health campaigns encouraging women to take a daily folic acid supplement, the proportion of reproductive age women, in the United States, who comply with this recommendation is less than optimal. The objective of this analysis was to identify predictors of preconceptional folic acid-containing supplement use to define subgroups of women who may benefit from targeted folic acid campaigns. This study included 6570 mothers of live born infants from the control population of National Birth Defects Prevention Study (1997-2005). Logistic regression analyses were used to identify predictors of preconceptional folic acid supplementation. A classification and regression tree (CART) analysis was used to define subgroups of women with different patterns of preconceptional folic acid supplementation. Race/ethnicity, education, age at delivery, nativity, employment, income, number of dependents, smoking, and birth control use were significantly associated with preconceptional folic acid-containing supplement use. Based on a CART analysis, education, race/ethnicity, and age were the most distinguishing factors between women with different preconceptional supplementation patterns. Non-white women with <4 years of a college education were the least likely to use folic acid-containing supplements (11%). However, even in the most compliant subgroup (women with ≥4 years of college), only 60% of women supplemented with folic acid. These results demonstrate the need for continued efforts to increase folic acid supplementation among all reproductive aged women. However, the success of such efforts may be improved if maternal characteristics such as education, race/ethnicity, and age, are considered in the development of future interventions. © 2014 Wiley Periodicals, Inc.

Maternal hypertension, medication use, and hypospadias in the National Birth Defects Prevention Study.

PubMed

Van Zutphen, Alissa R; Werler, Martha M; Browne, Marilyn M; Romitti, Paul A; Bell, Erin M; McNutt, Louise-Anne; Druschel, Charlotte M; Mitchell, Allen A

2014-02-01

To investigate whether antihypertensive classes and specific medications in early pregnancy increase the risk of severe hypospadias and to assess prior associations detected for late-treated and untreated hypertension in the National Birth Defects Prevention Study. Using telephone interviews from mothers of 2,131 children with severe hypospadias and 5,129 nonmalformed male control children for 1997-2009 births in a population-based case-control study, we estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) with multivariable logistic regression. We adjusted P values to account for multiple testing. Forty-eight (2.3%) case and 70 (1.4%) control mothers reported early pregnancy antihypertensive treatment, 45 (2.1%) case and 31 (0.6%) control mothers reported late treatment, and 315 (14.8%) case and 394 (7.7%) control mothers reported untreated hypertension. Selective β-blockers, centrally acting agents, renin-angiotensin system-acting agents, diuretics, and specific medications, methyldopa and atenolol, were not associated with hypospadias. Nonselective β-blockers (adjusted OR 3.22, 95% CI 1.47-7.05) were associated with hypospadias; however, P values adjusted for multiple testing were not statistically significant. We confirmed prior findings for associations between hypospadias and untreated hypertension (adjusted OR 2.09, 95% CI 1.76-2.48) and late initiation of treatment (adjusted OR 3.98, 95% CI 2.41-6.55). The increased risks would translate to severe hypospadias prevalences of 11.5, 17.7, and 21.9 per 10,000 births for women with untreated hypertension, nonselective β-blocker use, and late initiation of treatment, respectively. Our study suggests a relationship between hypospadias and the severity of hypertension. II.

Periconceptional folic acid prevents miscarriage in Irish families with neural tube defects.

PubMed

Byrne, J

2011-03-01

Miscarriages occur to excess in sibships with neural tube defects (NTDs) and among maternal versus paternal relatives in NTD families. Folic acid prevents most NTDs. Its potential to prevent miscarriages has been controversial. We evaluated the relationship of maternal line and periconceptional folic acid with miscarriage. First cousins in Irish families with NTDs were interviewed about pregnancy outcomes and the health of their offspring. Miscarriages were not more frequent among pregnancies of maternal versus paternal first cousins. Folic acid intake during early pregnancy significantly reduced the risk of miscarriage from 15.7 to 9.6%, for an adjusted odds ratio of 0.37 (95% confidence interval 0.19, 0.72, p = 0.005). Folic acid during pregnancy was associated with a reduction of approximately 60% in miscarriages. Miscarriages are common-one in every eight pregnancies in this study. If incorporated into pre-pregnancy counseling, these results could have significant public health impact.

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

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

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.

Facts about Birth Defects

MedlinePlus

... Defects Language: English (US) Español (Spanish) Recommend on Facebook Tweet Share Compartir On This Page Birth Defects are Common Identifying Birth Defects Causes Prevention References Birth defects are common, costly, and critical conditions that affect 1 in every 33 babies born in the ...

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

Maternal Medication and Herbal Use and Risk for Hypospadias: Data from the National Birth Defects Prevention Study, 1997--2007

PubMed Central

Lind, Jennifer N.; Tinker, Sarah C.; Broussard, Cheryl S.; Reefhuis, Jennita; Carmichael, Suzan L.; Honein, Margaret A.; Olney, Richard S.; Parker, Samantha E.; Werler, Martha M.

2014-01-01

Purpose Investigate associations between maternal use of common medications and herbals during early pregnancy and risk for hypospadias in male infants. Methods We used data from the National Birth Defects Prevention Study, a multi-site, population-based, case-control study. We analyzed data from 1,537 infants with second-or third-degree isolated hypospadias and 4,314 liveborn male control infants without major birth defects, with estimated dates of delivery from 1997–2007. Exposure was reported use of prescription or over-the-counter medications or herbal products, from 1 month before to 4 months after conception. Adjusted odds ratios (aORs) and 95% confidence intervals (CI) were estimated using multivariable logistic regression, adjusting for maternal age, race/ethnicity, education, pre-pregnancy BMI, previous live births, maternal sub-fertility, study site, and year. Results We assessed 64 medication and 24 herbal components. Maternal uses of most components were not associated with an increased risk of hypospadias. Two new associations were observed for venlafaxine (aOR 2.4; 95% CI 1.0, 6.0) and progestin only oral contraceptives (aOR 1.9, 95% CI 1.1, 3.2). The previously reported association for clomiphene citrate was confirmed (aOR 1.9, 95% CI 1.2, 3.0). Numbers were relatively small for exposure to other specific patterns of fertility agents, but elevated aORs were observed for the most common of them. Conclusions Overall, findings were reassuring that hypospadias is not associated with most medication components examined in this analysis. New associations will need to be confirmed in other studies. Increased risks for hypospadias associated with various fertility agents raises the possibility of confounding by underlying subfertility. PMID:23620412

Folic acid awareness among female college students: neural tube defects prevention.

PubMed

Kari, Jameela A; Bardisi, Ekhlas S; Baitalmal, Rabaa M; Ageely, Ghofran A

2008-12-01

To investigate the level of awareness among female college students on the importance of preconception folic acid supplementation in preventing neural tube defects (NTDs). We have also studied their response after educating them. This is a questionnaire-based study. Five hundreds questionnaires were distributed to the female students of the 3 colleges, namely, Humanities, Sciences, and Health in Jeddah, Kingdom of Saudi Arabia in April 2008. The questions included an enquiry on their knowledge regarding the importance of folic acid preconception, and if they will implement what they learned after listening to lectures, delivered by the 4th year medical students, who were trained and supervised by the faculty members of the King Abdul-Aziz University. Two hundred and seventeen questionnaires were filled, and returned (43.4%). Mean age +/- SD was 20.96 +/- 2.25 years. Almost 88% were not aware of the importance of folic acid in preventing NTDs. After listening to the lecture, 82.9% thought that they will surely use folic acid preconception, and 98.6% will relay the important message about the importance of folic acid to others. There is a need to increase the awareness of the importance of folic acid among females' childbearing age. Medical students' involvement in educating college students was an effective way to increase their awareness. Similar educating programs are required, in order to reduce the high incidence of NTDs.

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.

Integration of DNA sample collection into a multi-site birth defects case-control study.

PubMed

Rasmussen, Sonja A; Lammer, Edward J; Shaw, Gary M; Finnell, Richard H; McGehee, Robert E; Gallagher, Margaret; Romitti, Paul A; Murray, Jeffrey C

2002-10-01

Advances in quantitative analysis and molecular genotyping have provided unprecedented opportunities to add biological sampling and genetic information to epidemiologic studies. The purpose of this article is to describe the incorporation of DNA sample collection into the National Birth Defects Prevention Study (NBDPS), an ongoing case-control study in an eight-state consortium with a primary goal to identify risk factors for birth defects. Babies with birth defects are identified through birth defects surveillance systems in the eight participating centers. Cases are infants with one or more of over 30 major birth defects. Controls are infants without defects from the same geographic area. Epidemiologic information is collected through an hour-long interview with mothers of both cases and controls. We added the collection of buccal cytobrush DNA samples for case-infants, control-infants, and their parents to this study. We describe here the methods by which the samples have been collected and processed, establishment of a centralized resource for DNA banking, and quality control, database management, access, informed consent, and confidentiality issues. Biological sampling and genetic analyses are important components to epidemiologic studies of birth defects aimed at identifying risk factors. The DNA specimens collected in this study can be used for detection of mutations, study of polymorphic variants that confer differential susceptibility to teratogens, and examination of interactions among genetic risk factors. Information on the methods used and issues faced by the NBDPS may be of value to others considering the addition of DNA sampling to epidemiologic studies.

[Case-control study on influence factors of birth defects].

PubMed

Xiu, Xin-hong; Yuan, Li; Wang, Xiao-ming; Chen, Yu-hua; Wan, Ai-hua; Fu, Ping

2011-07-01

To investigate the influence factors of birth defects. The congenital malformational fetuses born from 13 week of gestation to 7 days after birth were selected as the study group between April 1st, 2009 and March 31st, 2010. The health born fetuses were set as control in the same period. Case-control and the three-level of monitor network of birth defects were used in the study in the participating 75 hospitals (Qingdao Women and Children's Medical Center, Affiliated Hospital of Medical College Qingdao University, Qingdao Municipal Hospital, etc.). The study and control group's parents were interviewed by an uniformed questionnaire which was designed specially with influence factors of birth defects. (1) There are 466 congenital malformational fetuses in the total of 77 231 fetuses collected in 75 hospitals. The congenital malformational rate accounts for about 6.034‰. The top six defect diseases were congenital heart disease (112 cases), total harelip (cleft lip; cleft lip with palate: 85 cases), polydactyly (53 cases), neural tube defects (38 cases), congenital hydrocephalus (37 cases) and limb reduction defect (27 cases) in turn, which amounts to 353 cases (54.48%, 353/648). (2) Their mother education level in the birth-defect group (25.6%) were significantly lower than that in control group (30.0%, P<0.05). (3) The rate of passive smoking, drinking, raising pets of the parents in birth-defect group were significantly higher than that in control group (P<0.05). (4) The rate of exposure to harmful chemical and physical factors of mothers in birth defects group (13.9% and 20.5%, respectively) was higher than that in control group (1.1% and 11.7%, respectively), the difference between which were significant (P<0.01). The rate of disease (34.3%), fever (13.1%), taking drugs (33.8%) in pregnancy period in birth defect group were higher than that in control group (13.5%, 1.5% and 9.9%, respectively), the difference between which were significant (P<0.01). The rate

A Knowledge-Based System For Analysis, Intervention Planning and Prevention of Defects in Immovable Cultural Heritage Objects and Monuments

NASA Astrophysics Data System (ADS)

Valach, J.; Cacciotti, R.; Kuneš, P.; ČerÅanský, M.; Bláha, J.

2012-04-01

The paper presents a project aiming to develop a knowledge-based system for documentation and analysis of defects of cultural heritage objects and monuments. The MONDIS information system concentrates knowledge on damage of immovable structures due to various causes, and preventive/remedial actions performed to protect/repair them, where possible. The currently built system is to provide for understanding of causal relationships between a defect, materials, external load, and environment of built object. Foundation for the knowledge-based system will be the systemized and formalized knowledge on defects and their mitigation acquired in the process of analysis of a representative set of cases documented in the past. On the basis of design comparability, used technologies, materials and the nature of the external forces and surroundings, the developed software system has the capacity to indicate the most likely risks of new defect occurrence or the extension of the existing ones. The system will also allow for a comparison of the actual failure with similar cases documented and will propose a suitable technical intervention plan. The system will provide conservationists, administrators and owners of historical objects with a toolkit for defect documentation for their objects. Also, advanced artificial intelligence methods will offer accumulated knowledge to users and will also enable them to get oriented in relevant techniques of preventive interventions and reconstructions based on similarity with their case.

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

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

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…

[Prevention of neural tube defects. An important health and social problem].

PubMed

Czochańska, J; Lech, M

1998-01-01

Central neural system congenital malformations in the form of neural tube defects (ntd) belong to the most common diseases leading to very serious childrens' disability and mortality. As it has been calculated, the number of children affected with ntd, delivered in Poland every year is in the range of 800-1150. Children with encephalocele participate in this number in app. 50%. As it has been found, morbidity and mortality caused by the ntd remain high and stable in Poland for the last 20 years. In the view of very limited possibilities of the treatment offered by health services, prophylactic measures remain the best methods for limitation of the problem. The primary prevention of ntd was discovered in late seventies. It has been found that folic acid added to the diet of women in the reproductive age reduced number of children born with ntd by 70%. Authors present the Programme of Primary Prevention of ntd in Poland. This Programme has been incorporated in the National Programme of Health for the Nation 1996-2005.

The use of folic acid for the prevention of birth defects in Puerto Rico

PubMed Central

García-Fragoso, Lourdes; García-García, Inés; Rivera, Cynthia E.

2009-01-01

Introduction The occurrence of neural tube defects (NTD) has been shown to vary by race/ethnicity, with the highest rates among women of Hispanic ethnicity. Women of reproductive age are advised to use folic acid to prevent NTD and other birth defects. Since 1994, Puerto Rico has a campaign to promote the use of folic acid and since 1998 there is fortification of enriched grain products. After fortification, there has been a reduction in the incidence of NTD in the island. The objective of this study is to assess the use of folic acid by women of reproductive age in Puerto Rico and determine factors associated to its use. Methods A self-administered questionnaire was answered by 964 women around the island. Results Folic acid consumption was reported by 30% of the participants, 21% reported to consume it at least 4 times per week, and only 14% consumed it the day before the survey. Knowledge about the recommendation for women to consume folic acid was reported by 97% of the participants. The use of folic acid was lower among women of lower education and lower social class. Women with higher education were 8.3 times more likely to consume folic acid. Conclusion The folic acid campaign has improved women’s knowledge about the recommendation for folic acid supplementation. Nevertheless, its use is lower than desired to continue reducing the incidence of birth defects in Puerto Rico. Education and social class continue to represent barriers to eliminate the disparities in the pre-conception health of our population. PMID:18646342

Enzyme Replacement Therapy Prevents Dental Defects in a Model of Hypophosphatasia

PubMed Central

McKee, M.D.; Nakano, Y.; Masica, D.L.; Gray, J.J.; Lemire, I.; Heft, R.; Whyte, M.P.; Crine, P.; Millán, J.L.

2011-01-01

Hypophosphatasia (HPP) occurs from loss-of-function mutation in the tissue-non-specific alkaline phosphatase (TNALP) gene, resulting in extracellular pyrophosphate accumulation that inhibits skeletal and dental mineralization. TNALP-null mice (Akp2-/-) phenocopy human infantile hypophosphatasia; they develop rickets at 1 week of age, and die before being weaned, having severe skeletal and dental hypomineralization and episodes of apnea and vitamin B6-responsive seizures. Delay and defects in dentin mineralization, together with a deficiency in acellular cementum, are characteristic. We report the prevention of these dental abnormalities in Akp2-/- mice receiving treatment from birth with daily injections of a mineral-targeting, human TNALP (sALP-FcD10). sALP-FcD10 prevented hypomineralization of alveolar bone, dentin, and cementum as assessed by micro-computed tomography and histology. Osteopontin – a marker of acellular cementum – was immuno-localized along root surfaces, confirming that acellular cementum, typically missing or reduced in Akp2-/- mice, formed normally. Our findings provide insight concerning how acellular cementum is formed on tooth surfaces to effect periodontal ligament attachment to retain teeth in their osseous alveolar sockets. Furthermore, they provide evidence that this enzyme-replacement therapy, applied early in post-natal life – where the majority of tooth root development occurs, including acellular cementum formation – could prevent the accelerated tooth loss seen in individuals with HPP. PMID:21212313

Enzyme replacement therapy prevents dental defects in a model of hypophosphatasia.

PubMed

McKee, M D; Nakano, Y; Masica, D L; Gray, J J; Lemire, I; Heft, R; Whyte, M P; Crine, P; Millán, J L

2011-04-01

Hypophosphatasia (HPP) occurs from loss-of-function mutation in the tissue-non-specific alkaline phosphatase (TNALP) gene, resulting in extracellular pyrophosphate accumulation that inhibits skeletal and dental mineralization. TNALP-null mice (Akp2(-/-)) phenocopy human infantile hypophosphatasia; they develop rickets at 1 week of age, and die before being weaned, having severe skeletal and dental hypomineralization and episodes of apnea and vitamin B(6)-responsive seizures. Delay and defects in dentin mineralization, together with a deficiency in acellular cementum, are characteristic. We report the prevention of these dental abnormalities in Akp2(-/-) mice receiving treatment from birth with daily injections of a mineral-targeting, human TNALP (sALP-FcD(10)). sALP-FcD(10) prevented hypomineralization of alveolar bone, dentin, and cementum as assessed by micro-computed tomography and histology. Osteopontin--a marker of acellular cementum--was immuno-localized along root surfaces, confirming that acellular cementum, typically missing or reduced in Akp2(-/-) mice, formed normally. Our findings provide insight concerning how acellular cementum is formed on tooth surfaces to effect periodontal ligament attachment to retain teeth in their osseous alveolar sockets. Furthermore, they provide evidence that this enzyme-replacement therapy, applied early in post-natal life--where the majority of tooth root development occurs, including acellular cementum formation--could prevent the accelerated tooth loss seen in individuals with HPP.

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. Copyright © 2013 The Author. Published by Elsevier Ltd.. All rights reserved.

NMDA Receptor Signaling Is Important for Neural Tube Formation and for Preventing Antiepileptic Drug-Induced Neural Tube Defects.

PubMed

Sequerra, Eduardo B; Goyal, Raman; Castro, Patricio A; Levin, Jacqueline B; Borodinsky, Laura N

2018-05-16

Failure of neural tube closure leads to neural tube defects (NTDs), which can have serious neurological consequences or be lethal. Use of antiepileptic drugs (AEDs) during pregnancy increases the incidence of NTDs in offspring by unknown mechanisms. Here we show that during Xenopus laevis neural tube formation, neural plate cells exhibit spontaneous calcium dynamics that are partially mediated by glutamate signaling. We demonstrate that NMDA receptors are important for the formation of the neural tube and that the loss of their function induces an increase in neural plate cell proliferation and impairs neural cell migration, which result in NTDs. We present evidence that the AED valproic acid perturbs glutamate signaling, leading to NTDs that are rescued with varied efficacy by preventing DNA synthesis, activating NMDA receptors, or recruiting the NMDA receptor target ERK1/2. These findings may prompt mechanistic identification of AEDs that do not interfere with neural tube formation. SIGNIFICANCE STATEMENT Neural tube defects are one of the most common birth defects. Clinical investigations have determined that the use of antiepileptic drugs during pregnancy increases the incidence of these defects in the offspring by unknown mechanisms. This study discovers that glutamate signaling regulates neural plate cell proliferation and oriented migration and is necessary for neural tube formation. We demonstrate that the widely used antiepileptic drug valproic acid interferes with glutamate signaling and consequently induces neural tube defects, challenging the current hypotheses arguing that they are side effects of this antiepileptic drug that cause the increased incidence of these defects. Understanding the mechanisms of neurotransmitter signaling during neural tube formation may contribute to the identification and development of antiepileptic drugs that are safer during pregnancy. Copyright © 2018 the authors 0270-6474/18/384762-12$15.00/0.

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.

Characterizing and Targeting Replication Stress Response Defects in Breast Cancer

DTIC Science & Technology

2011-08-01

induced RSR breast cell model, in which cyclin E can be conditionally induced to trigger RSR in normal breast cells. Using this model, we demonstrated...which makes these defects effective targets for both breast cancer prevention and breast cancer treatment. This project is to use cutting-edge...defective RSR; identify drugs that target these defects; and develop RSR-defect-targeting nanoparticles for diagnostic imaging, prevention, and

Defective prevention of immune precipitation in autoimmune diseases is independent of C4A*Q0

PubMed Central

Arason, G J; Kolka, R; Hreidarsson, A B; Gudjonsson, H; Schneider, P M; Fry, L; Arnason, A

2005-01-01

Increased prevalence of C4 null alleles is a common feature of autoimmune diseases. We have shown previously that complement-dependent prevention of immune precipitation (PIP) is defective in patients with systemic lupus erythematosus (SLE), and correlated this defect with C4A*Q0 and low levels of the C4A isotype. To further clarify the role of C4A in the aetiology of SLE, we now extend our studies to other diseases which have been associated with C4A*Q0. The frequency of C4A*Q0 was increased in Icelandic patients with coeliac disease (0·50; P < 0·001), Grave's disease (0·30; P = 0·002) and insulin-dependent diabetes mellitus (0·23; P = 0·04) and in British patients with dermatitis herpetiformis (0·42; P = 0·002) and this was reflected in low levels of C4A. In spite of this, PIP was normal in these patients, and in marked contrast to our previous observations on connective tissue diseases, PIP measurements in these patient groups correlated more strongly with levels of C4B (r = 0·51, P = 0·0000004) than C4A. Patients with increased levels of anti-C1q antibodies had significantly lower PIP than patients without such antibodies (P < 0·01) and a negative association of PIP with anti-C1q antibodies was also reflected in an increased prevalence (P = 0·006) and levels (P = 0·006) of anti-C1q antibodies in patients with subnormal PIP, as well as a negative correlation between PIP and anti-C1q antibodies (r = − 0·25, P = 0·02). These results show that the PIP defect cannot be explained by low levels of C4A alone and suggest that measurements of anti-C1q antibodies may be useful in future studies on the molecular cause of the PIP defect in autoimmune connective tissue disease. PMID:15932521

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.

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

PREFACE: The International Workshop on Positron Studies of Defects 2014

NASA Astrophysics Data System (ADS)

Sugita, Kazuki; Shirai, Yasuharu

2016-01-01

The International Workshop on Positron Studies of Defects 2014 (PSD-14) was held in Kyoto, Japan from 14-19 September, 2014. The PSD Workshop brought together positron scientists interested in studying defects to an international platform for presenting and discussing recent results and achievements, including new experimental and theoretical methods in the field. The workshop topics can be characterized as follows: • Positron studies of defects in semiconductors and oxides • Positron studies of defects in metals • New experimental methods and equipment • Theoretical calculations and simulations of momentum distributions, positron lifetimes and other characteristics for defects • Positron studies of defects in combination with complementary methods • Positron beam studies of defects at surfaces, interfaces, in sub-surface regions and thin films • Nanostructures and amorphous materials

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).

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.

Neural Tube Defects

PubMed Central

Greene, Nicholas D.E.; Copp, Andrew J.

2015-01-01

Neural tube defects (NTDs), including spina bifida and anencephaly, are severe birth defects of the central nervous system that originate during embryonic development when the neural tube fails to close completely. Human NTDs are multifactorial, with contributions from both genetic and environmental factors. The genetic basis is not yet well understood, but several nongenetic risk factors have been identified as have possibilities for prevention by maternal folic acid supplementation. Mechanisms underlying neural tube closure and NTDs may be informed by experimental models, which have revealed numerous genes whose abnormal function causes NTDs and have provided details of critical cellular and morphological events whose regulation is essential for closure. Such models also provide an opportunity to investigate potential risk factors and to develop novel preventive therapies. PMID:25032496

Crystal defect studies using x-ray diffuse scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 intomore » 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.« less

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.

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

Interproximal periodontal defect model in dogs: a pilot study.

PubMed

Jung, U-W; Chang, Y-Y; Um, Y-J; Kim, C-S; Cho, K-S; Choi, S-H

2011-01-01

This study aimed to evaluate the validity of a surgically created interproximal periodontal defect in dogs. Surgery was performed in the interproximal area between the maxillary second and third premolars in two beagle dogs. Following an incision and reflection of the gingival flap, a 3-mm wide and 5-mm high defect was prepared surgically at the interproximal area. A thorough root planing was performed and the flap was coronally positioned and sutured. The contra-lateral area was served as the control with no surgical intervention. After 8 weeks of healing, the animals were killed and the defect was analysed histometrically and radiographically. The interproximal periodontal defect resembled a naturally occurring defect and mimicked a clinical situation. After healing, the defect showed limited bone (0.89±0.02mm) and cementum regeneration (1.50± 0.48mm). Within the limitations of this pilot study, the interproximal periodontal defect showed limited bone and cementum regeneration. Thus, it can be considered as a standardized, reproducible defect model for testing new biomaterials. © 2010 John Wiley & Sons A/S.

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.

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

A case–control study of maternal bathing habits and risk for birth defects in offspring

PubMed Central

2013-01-01

Background Nearly all women shower or take baths during early pregnancy; however, bathing habits (i.e., shower and bath length and frequency) may be related to the risk of maternal hyperthermia and exposure to water disinfection byproducts, both of which are suspected to increase risk for multiple types of birth defects. Thus, we assessed the relationships between bathing habits during pregnancy and the risk for several nonsyndromic birth defects in offspring. Methods Data for cases with one of 13 types of birth defects and controls from the National Birth Defects Prevention Study delivered during 2000–2007 were evaluated. Logistic regression analyses were conducted separately for each type of birth defect. Results There were few associations between shower frequency or bath frequency or length and risk for birth defects in offspring. The risk for gastroschisis in offspring was increased among women who reported showers lasting ≥15 compared to <15 minutes (adjusted odds ratio: 1.43, 95% confidence interval: 1.18-1.72). In addition, we observed modest increases in the risk for spina bifida, cleft lip with or without cleft palate, and limb reduction defects in offspring of women who showered ≥15 compared to <15 minutes. The results of comparisons among more specific categories of shower length (i.e., <15 minutes versus 15–19, 20–29, and ≥ 30 minutes) were similar. Conclusions Our findings suggest that shower length may be associated with gastroschisis, but the modest associations with other birth defects were not supported by analyses of bath length or bath or shower frequency. Given that showering for ≥15 minutes during pregnancy is very common, further evaluation of the relationship between maternal showering habits and birth defects in offspring is worthwhile. PMID:24131571

Triple surveillance: a proposal for an integrated strategy to support and accelerate birth defect prevention

PubMed Central

Mastroiacovo, Pierpaolo

2018-01-01

Abstract Preventing neural tube defects (NTDs) easily qualifies as a high‐value opportunity to improve childhood survival and health: the unmet need is significant (major preventable burden), the intervention is transformative (providing sufficient folic acid), and delivery strategies (e.g., fortification) are effective in low‐resource countries. Yet, NTD prevention is lagging. Can public health surveillance help fix this problem? Critics contend that surveillance is largely unnecessary, that limited resources are best spent on interventions, and that surveillance is unrealistic in developing countries. The counterargument is twofold: (1) in the absence of surveillance, interventions will provide fewer benefits and cost more and (2) effective surveillance is likely possible nearly everywhere, with appropriate strategies. As a base strategy, we propose “triple surveillance:” integrating surveillance of cause (folate insufficiency), of disease occurrence (NTD prevalence), and of health outcomes (morbidity, mortality, and disability). For better sustainability and usefulness, it is crucial to refocus and streamline surveillance activities (no recreational data collection), weave surveillance into clinical care (integrate in clinical workflow), and, later, work on including additional risk factors and pediatric outcomes (increase benefits at low marginal cost). By doing so, surveillance becomes not a roadblock but a preferential path to prevention and better care. PMID:29532515

Delamination initiated by a defect

NASA Astrophysics Data System (ADS)

Biel, A.; Toftegaard, H.

2016-07-01

Composite materials in wind turbines are mainly joined with adhesives. Adhesive joining is preferable since it distributes the stresses over a larger area. This study shows how a defect can influence the fracture behaviour of adhesively joined composite. Repeated experiments are performed using double cantilever beam specimens loaded with bending moments. The specimens consist of two 8 mm thick GFRP-laminates which are joined by a 3 mm thick epoxy adhesive. A thin foil close to one of the laminates is used to start the crack. For some of the specimens a defect is created by an initial load-unload operation. During this operation, a clamp is used in order to prevent crack propagation in the main direction. For the specimens without defect, the crack propagates in the middle of the adhesive layer. For the specimens with defect, the crack directly deviates into the laminate. After about 25 mm propagation in the laminate, the crack returns to the adhesive. Compared to the adhesive the fracture energy for the laminate is significantly higher.

Triple surveillance: a proposal for an integrated strategy to support and accelerate birth defect prevention.

PubMed

Botto, Lorenzo D; Mastroiacovo, Pierpaolo

2018-02-01

Preventing neural tube defects (NTDs) easily qualifies as a high-value opportunity to improve childhood survival and health: the unmet need is significant (major preventable burden), the intervention is transformative (providing sufficient folic acid), and delivery strategies (e.g., fortification) are effective in low-resource countries. Yet, NTD prevention is lagging. Can public health surveillance help fix this problem? Critics contend that surveillance is largely unnecessary, that limited resources are best spent on interventions, and that surveillance is unrealistic in developing countries. The counterargument is twofold: (1) in the absence of surveillance, interventions will provide fewer benefits and cost more and (2) effective surveillance is likely possible nearly everywhere, with appropriate strategies. As a base strategy, we propose "triple surveillance:" integrating surveillance of cause (folate insufficiency), of disease occurrence (NTD prevalence), and of health outcomes (morbidity, mortality, and disability). For better sustainability and usefulness, it is crucial to refocus and streamline surveillance activities (no recreational data collection), weave surveillance into clinical care (integrate in clinical workflow), and, later, work on including additional risk factors and pediatric outcomes (increase benefits at low marginal cost). By doing so, surveillance becomes not a roadblock but a preferential path to prevention and better care. © 2018 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals, Inc. on behalf of New York Academy of Sciences.

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

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.

A Study of Defect Behavior in Almandine Garnet

NASA Astrophysics Data System (ADS)

Geiger, C. A.; Brearley, A. J.; Dachs, E.; Tipplet, G.; Rossman, G. R.

2016-12-01

Transport and diffusion in crystals are controlled by defects. However, a good understanding of the defect types in many silicates, including garnet, is not at hand. We undertook a study on synthetic almandine, ideal end-member Fe3Al2Si3O12, to better understand its precise chemical and physical properties and defect behavior. Crystals were synthesized at high pressures and temperatures under different fO2 conditions using various starting materials with H2O and without. The almandine obtained came in polycrystalline and single-crystal form. The synthetic reaction products and crystals were carefully characterized using X-ray powder diffraction, electron microprobe and TEM analysis and with 57Fe Mössbauer, UV/VIS single-crystal absorption and IR single-crystal spectroscopy. Various possible intrinsic defects, such as the Frenkel, Schottky and site-disorder types, along with Fe3+, in both synthetic and natural almandine crystals, were analyzed based on model defects expressed in Kröger-Vink notation. Certain types of minor microscopic- to macroscopic-sized precipitation or exsolution phases, including some that are nanosized, that are observed in synthetic almandine (e.g., magnetite), as well as in more compositionally complex natural crystals (e.g., magnetite, rutile, ilmenite), may result from defect reactions. An explanation for their origin through minor amounts of defects in garnet has certain advantages over other models that have been put forth in the literature that assume strict garnet stoichiometry for their formation and/or open-system atomic transport over relatively long length scales. Physical properties, including magnetic, electrical conductivity and diffusion behavior, as well as the color, of almandine are also analyzed in terms of various possible model defects. It is difficult, if not impossible, to synthesize stoichiometric end-member almandine, Fe3Al2Si3O12, in the laboratory, as small amounts of extrinsic OH- and/or Fe3+ defects, for example

Computer programs for eddy-current defect studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 aremore » 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.« less

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.

Recurrent neural tube defects, risk factors and vitamins.

PubMed Central

Wild, J; Read, A P; Sheppard, S; Seller, M J; Smithells, R W; Nevin, N C; Schorah, C J; Fielding, D W; Walker, S; Harris, R

1986-01-01

Data from our trial of periconceptional vitamin supplementation for the prevention of neural tube defects have been analysed to assess the influence of various factors on recurrence rates of neural tube defect. Our data suggest that the risk of recurrence of neural tube defect is influenced by the number of previous neural tube defects, area of residence, immediately prior miscarriage, and interpregnancy interval. None of these factors, however, contributed any significant differential risk between supplemented and unsupplemented mothers. Hence we conclude that the highly significant difference in recurrence rates of neural tube defect between supplemented and unsupplemented mothers was due to vitamin supplementation. PMID:3521496

Neural Tube Defects and Maternal Folate Intake Among Pregnancies Conceived After Folic Acid Fortification in the United States

PubMed Central

Mosley, Bridget S.; Cleves, Mario A.; Siega-Riz, Anna Maria; Shaw, Gary M.; Canfield, Mark A.; Waller, D. Kim; Werler, Martha M.

2009-01-01

Rates of neural tube defects have decreased since folic acid fortification of the food supply in the United States. The authors’ objective was to evaluate the associations between neural tube defects and maternal folic acid intake among pregnancies conceived after fortification. This is a multicenter, case-control study that uses data from the National Birth Defects Prevention Study, 1998–2003. Logistic regression was used to compute crude and adjusted odds ratios between cases and controls assessing maternal periconceptional use of folic acid and intake of dietary folic acid. Among 180 anencephalic cases, 385 spina bifida cases, and 3, 963 controls, 21.1%, 25.2%, and 26.1%, respectively, reported periconceptional use of folic acid supplements. Periconceptional supplement use did not reduce the risk of having a pregnancy affected by a neural tube defect. Maternal intake of dietary folate was not significantly associated with neural tube defects. In this study conducted among pregnancies conceived after mandatory folic acid fortification, the authors found little evidence of an association between neural tube defects and maternal folic acid intake. A possible explanation is that folic acid fortification reduced the occurrence of folic acid-sensitive neural tube defects. Further investigation is warranted to possibly identify women who remain at increased risk of preventable neural tube defects. PMID:18953063

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

HgCdTe Surface and Defect Study Program.

DTIC Science & Technology

1986-03-01

different potential for Hg and Cd and hence be reflected in the electronic structure. The techniques of PES and ARPES available to our research group ...D-A166 795 HOME SURFCE ND DEFECT STUDY PROQRN(U) SATA / BARBRA RESEARCH CENTER GOLETA CALXF J A WILSON ET AL. USI FE MAR 86 SBRC-60411 ND93-63-C...0168 FO2/2 N L6 ILO 1.5 1. 11111 .6 .ICnrnp CHR HgCdTo SURFACE AND DEFECT STUDY PROGRAM J. A. Wilson and V. A. Cotton Santa Barbara Research Center

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.

First-Principles Study of Defects in GaN

DTIC Science & Technology

2009-07-29

This means both Mg and Be are not suitable p-type dopants in AlN. c) We have calculated the Ga Frenkel pairs (interstitial Ga and gallium vacancy... gallium vacancy complexes) in GaN. We studied both the stability of the pair at different separations and the barriers for the pair to form/disintegrate...high in energy than vacancy defects, especially for covalent materials. However, in ionic materials the charged interstitial defects can have low

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.

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. Copyright © 2017 Elsevier Inc. All rights reserved.

Defect studies of thin ZnO films prepared by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Vlček, M.; Čížek, J.; Procházka, I.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Mosnier, J.-P.

2014-04-01

Thin ZnO films were grown by pulsed laser deposition on four different substrates: sapphire (0 0 0 1), MgO (1 0 0), fused silica and nanocrystalline synthetic diamond. Defect studies by slow positron implantation spectroscopy (SPIS) revealed significantly higher concentration of defects in the studied films when compared to a bulk ZnO single crystal. The concentration of defects in the films deposited on single crystal sapphire and MgO substrates is higher than in the films deposited on amorphous fused silica substrate and nanocrystalline synthetic diamond. Furthermore, the effect of deposition temperature on film quality was investigated in ZnO films deposited on synthetic diamond substrates. Defect studies performed by SPIS revealed that the concentration of defects firstly decreases with increasing deposition temperature, but at too high deposition temperatures it increases again. The lowest concentration of defects was found in the film deposited at 450° C.

Effect of point defects and disorder on structural phase transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toulouse, J.

1997-06-01

Since the beginning in 1986, the object of this project has been Structural Phase Transitions (SPT) in real as opposed to ideal materials. The first stage of the study has been centered around the role of Point Defects in SPT`s. Our intent was to use the previous knowledge we had acquired in the study of point defects in non-transforming insulators and apply it to the study of point defects in insulators undergoing phase transitions. In non-transforming insulators, point defects, in low concentrations, marginally affect the bulk properties of the host. It is nevertheless possible by resonance or relaxation methods tomore » study the point defects themselves via their local motion. In transforming solids, however, close to a phase transition, atomic motions become correlated over very large distances; there, even point defects far removed from one another can undergo correlated motions which may strongly affect the transition behavior of the host. Near a structural transition, the elastic properties win be most strongly affected so as to either raise or decrease the transition temperature, prevent the transition from taking place altogether, or simply modify its nature and the microstructure or domain structure of the resulting phase. One of the well known practical examples is calcium-stabilized zirconia in which the high temperature cubic phase is stabilized at room temperature with greatly improved mechanical properties.« less

Prevention of esophageal strictures after endoscopic submucosal dissection

PubMed Central

Kobayashi, Shinichiro; Kanai, Nobuo; Ohki, Takeshi; Takagi, Ryo; Yamaguchi, Naoyuki; Isomoto, Hajime; Kasai, Yoshiyuki; Hosoi, Takahiro; Nakao, Kazuhiko; Eguchi, Susumu; Yamamoto, Masakazu; Yamato, Masayuki; Okano, Teruo

2014-01-01

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have recently been accepted as less invasive methods for treating patients with early esophageal cancers such as squamous cell carcinoma and dysplasia of Barrett’s esophagus. However, the large defects in the esophageal mucosa often cause severe esophageal strictures, which dramatically reduce the patient’s quality of life. Although preventive endoscopic balloon dilatation can reduce dysphagia and the frequency of dilatation, other approaches are necessary to prevent esophageal strictures after ESD. This review describes several strategies for preventing esophageal strictures after ESD, with a particular focus on anti-inflammatory and tissue engineering approaches. The local injection of triamcinolone acetonide and other systemic steroid therapies are frequently used to prevent esophageal strictures after ESD. Tissue engineering approaches for preventing esophageal strictures have recently been applied in basic research studies. Scaffolds with temporary stents have been applied in five cases, and this technique has been shown to be safe and is anticipated to prevent esophageal strictures. Fabricated autologous oral mucosal epithelial cell sheets to cover the defective mucosa similarly to how commercially available skin products fabricated from epidermal cells are used for skin defects or in cases of intractable ulcers. Fabricated autologous oral-mucosal-epithelial cell sheets have already been shown to be safe. PMID:25386058

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. Copyright © 2015 Elsevier Inc. All rights reserved.

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

Progesterone Prevents High-Grade Serous Ovarian Cancer by Inducing Necroptosis of p53-Defective Fallopian Tube Epithelial Cells.

PubMed

Wu, Na-Yiyuan; Huang, Hsuan-Shun; Chao, Tung Hui; Chou, Hsien Ming; Fang, Chao; Qin, Chong-Zhen; Lin, Chueh-Yu; Chu, Tang-Yuan; Zhou, Hong Hao

2017-03-14

High-grade serous ovarian carcinoma (HGSOC) originates mainly from the fallopian tube (FT) epithelium and always carries early TP53 mutations. We previously reported that tumors initiate in the FT fimbria epithelium because of apoptotic failure and the expansion of cells with DNA double-strand breaks (DSB) caused by bathing of the FT epithelial cells in reactive oxygen species (ROSs) and hemoglobin-rich follicular fluid (FF) after ovulation. Because ovulation is frequent and HGSOC is rare, we hypothesized that luteal-phase progesterone (P4) could eliminate p53-defective FT cells. Here we show that P4, via P4 receptors (PRs), induces necroptosis in Trp53 -/- mouse oviduct epithelium and in immortalized human p53-defective fimbrial epithelium through the TNF-α/RIPK1/RIPK3/MLKL pathway. Necroptosis occurs specifically at diestrus, recovers at the proestrus phase of the estrus cycle, and can be augmented with P4 supplementation. These results reveal the mechanism of the well-known ability of progesterone to prevent ovarian cancer. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Serine biosynthesis and transport defects.

PubMed

El-Hattab, Ayman W

2016-07-01

l-serine is a non-essential amino acid that is biosynthesized via the enzymes phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). Besides its role in protein synthesis, l-serine is a potent neurotrophic factor and a precursor of a number of essential compounds including phosphatidylserine, sphingomyelin, glycine, and d-serine. Serine biosynthesis defects result from impairments of PGDH, PSAT, or PSP leading to systemic serine deficiency. Serine biosynthesis defects present in a broad phenotypic spectrum that includes, at the severe end, Neu-Laxova syndrome, a lethal multiple congenital anomaly disease, intermediately, infantile serine biosynthesis defects with severe neurological manifestations and growth deficiency, and at the mild end, the childhood disease with intellectual disability. A serine transport defect resulting from deficiency of the ASCT1, the main transporter for serine in the central nervous system, has been recently described in children with neurological manifestations that overlap with those observed in serine biosynthesis defects. l-serine therapy may be beneficial in preventing or ameliorating symptoms in serine biosynthesis and transport defects, if started before neurological damage occurs. Herein, we review serine metabolism and transport, the clinical, biochemical, and molecular aspects of serine biosynthesis and transport defects, the mechanisms of these diseases, and the potential role of serine therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

Defective Reduction in Frozen Pie Manufacturing Process

NASA Astrophysics Data System (ADS)

Nooted, Oranuch; Tangjitsitcharoen, Somkiat

2017-06-01

The frozen pie production has a lot of defects resulting in high production cost. Failure mode and effect analysis (FMEA) technique has been applied to improve the frozen pie process. Pareto chart is also used to determine the major defects of frozen pie. There are 3 main processes that cause the defects which are the 1st freezing to glazing process, the forming process, and the folding process. The Risk Priority Number (RPN) obtained from FMEA is analyzed to reduce the defects. If RPN of each cause exceeds 45, the process will be considered to be improved and selected for the corrective and preventive actions. The results showed that RPN values decreased after the correction. Therefore, the implementation of FMEA technique can help to improve the performance of frozen pie process and reduce the defects approximately 51.9%.

Study on the intrinsic defects in tin oxide with first-principles method

NASA Astrophysics Data System (ADS)

Sun, Yu; Liu, Tingyu; Chang, Qiuxiang; Ma, Changmin

2018-04-01

First-principles and thermodynamic methods are used to study the contribution of vibrational entropy to defect formation energy and the stability of the intrinsic point defects in SnO2 crystal. According to thermodynamic calculation results, the contribution of vibrational entropy to defect formation energy is significant and should not be neglected, especially at high temperatures. The calculated results indicate that the oxygen vacancy is the major point defect in undoped SnO2 crystal, which has a higher concentration than that of the other point defect. The property of negative-U is put forward in SnO2 crystal. In order to determine the most stable defects much clearer under different conditions, the most stable intrinsic defect as a function of Fermi level, oxygen partial pressure and temperature are described in the three-dimensional defect formation enthalpy diagrams. The diagram visually provides the most stable point defects under different conditions.

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.

3D modeling of missing pellet surface defects in BWR fuel

DOE PAGES

Spencer, B. W.; Williamson, R. L.; Stafford, D. S.; ...

2016-07-26

One of the important roles of cladding in light water reactor fuel rods is to prevent the release of fission products. To that end, it is essential that the cladding maintain its integrity under a variety of thermal and mechanical loading conditions. Local geometric irregularities in fuel pellets caused by manufacturing defects known as missing pellet surfaces (MPS) can in some circumstances lead to elevated cladding stresses that are sufficiently high to cause cladding failure. Accurate modeling of these defects can help prevent these types of failures. The BISON nuclear fuel performance code developed at Idaho National Laboratory can bemore » used to simulate the global thermo-mechanical fuel rod behavior, as well as the local response of regions of interest, in either 2D or 3D. In either case, a full set of models to represent the thermal and mechanical properties of the fuel, cladding and plenum gas is employed. A procedure for coupling 2D full-length fuel rod models to detailed 3D models of the region of the rod containing a MPS defect is detailed in this paper. The global and local model each contain appropriate physics and behavior models for nuclear fuel. This procedure is demonstrated on a simulation of a boiling water reactor (BWR) fuel rod containing a pellet with an MPS defect, subjected to a variety of transient events, including a control blade withdrawal and a ramp to high power. The importance of modeling the local defect using a 3D model is highlighted by comparing 3D and 2D representations of the defective pellet region. Finally, parametric studies demonstrate the effects of the choice of gaseous swelling model and of the depth and geometry of the MPS defect on the response of the cladding adjacent to the defect.« less

Bone compositional study during healing of subcritical calvarial defects in rats by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Ahmed, Rafay; Wing Lun Law, Alan; Cheung, Tsz Wing; Lau, Condon

2017-07-01

Subcritical calvarial defects are important to study bone regeneration during healing. In this study 1mm calvarial defects were created using trephine in the parietal bones of Sprague-Dawley rats (n=7) that served as in vivo defects. Subjects were sacrificed after 7 days and the additional defects were created on the harvested skull with the same method to serve as control defects. Raman spectroscopy is established to investigate mineral/matrix ratio, carbonate/phosphate ratio and crystallinity of three different surfaces; in vivo defects, control defects and normal surface. Results show 21% and 23% decrease in mineral/matrix after 7 days of healing from surface to in vivo and control to in vivo defects, respectively. Carbonate to phosphate ratio was found to be increased by 39% while crystallinity decreased by 26% in both surface to in vivo and control to in vivo defects. This model allows to study the regenerated bone without mechanically perturbing healing surface.

Agrichemicals in surface water and birth defects in the United States

PubMed Central

Winchester, Paul D; Huskins, Jordan; Ying, Jun

2009-01-01

Objectives: To investigate if live births conceived in months when surface water agrichemicals are highest are at greater risk for birth defects. Methods: Monthly concentrations during 1996–2002 of nitrates, atrazine and other pesticides were calculated using United States Geological Survey's National Water Quality Assessment data. Monthly United States birth defect rates were calculated for live births from 1996 to 2002 using United States Centers for Disease Control and Prevention natality data sets. Birth defect rates by month of last menstrual period (LMP) were then compared to pesticide/nitrate means using logistical regression models. Results: Mean concentrations of agrichemicals were highest in April–July. Total birth defects, and eleven of 22 birth defect subcategories, were more likely to occur in live births with LMPs between April and July. A significant association was found between the season of elevated agrichemicals and birth defects. Conclusion: Elevated concentrations of agrichemicals in surface water in April–July coincided with higher risk of birth defects in live births with LMPs April–July. While a causal link between agrichemicals and birth defects cannot be proven from this study an association might provide clues to common factors shared by both variables. PMID:19183116

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.

Studies of Point Defects and Defect Interactions in Metals Using Perturbed Gamma Gamma Angular Correlations

NASA Astrophysics Data System (ADS)

Shropshire, Steven Leslie

Point defects in plastically deformed Au, Pt, and Ni were studied with atomic-scale sensitivity using the perturbed gamma-gamma angular correlations (PAC) technique by monitoring formation and transformation of complexes of vacancy defects with very dilute ^{111}In/ ^{111}Cd solute probes. Three topics were investigated: (1) Production of vacancy defects during plastic deformation of Au was investigated to differentiate models of defect production. Concentrations of mono-, di-, and tri-vacancy species were measured in Au, and the ratio of mono- to di-vacancies was found to be independent of the amount of deformation. Results indicate that point defects are produced in correlated lattice locations, such as in "strings", as a consequence of dislocation interactions and not at random locations. (2) Hydrogen interactions with vacancy-solute complexes were studied in Pt. From thermal detrapping experiments, binding of hydrogen in complexes with mono-, di- and tri-vacancies was determined using a model for hydrogen diffusing in a medium with traps, with enthalpies all measured in the narrow range 0.23-0.28 eV, proving that the binding is insensitive to the precise structure of small vacancy clusters. Nuclear relaxation of the probe in a trivacancy complex in Pt was studied as a function of temperature, from which an activation energy of 0.34 eV was measured. This value is inconsistent with relaxation caused by diffusion or trapping of hydrogen, but explainable by dynamical hopping of the PAC probe atom in a cage of vacancies. (3) By observing transformations between vacancy-solute complexes induced by annihilation reactions, it was demonstrated that interstitials are produced during plastic deformation. The evolution of concentrations of the different vacancy complexes under an interstitial flux was measured and analyzed using a kinetic-rate model, from which interstitial capture cross-sections for the different vacancy complexes and the relative quantities of

Lack of periconceptional vitamins or supplements that contain folic acid and diabetes mellitus-associated birth defects.

PubMed

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

2012-03-01

The purpose of this study was to examine the risk of birth defects in relation to diabetes mellitus and the lack of use of periconceptional vitamins or supplements that contain folic acid. The National Birth Defects Prevention Study (1997-2004) is a multicenter, population-based case-control study of birth defects (14,721 cases and 5437 control infants). Cases were categorized into 18 types of heart defects and 26 noncardiac birth defects. We estimated odds ratios for independent and joint effects of preexisting diabetes mellitus and a lack of periconceptional use of vitamins or supplements that contain folic acid. The pattern of odds ratios suggested an increased risk of defects that are associated with diabetes mellitus in the absence vs the presence of the periconceptional use of vitamins or supplements that contain folic acid. The lack of periconceptional use of vitamins or supplements that contain folic acid may be associated with an excess risk for birth defects due to diabetes mellitus. Published by Mosby, Inc.

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.

Folic acid and birth defect prevention

MedlinePlus

Preconceptional counseling. In: Cunningham FG, Leveno KL, Bloom SL, et al, eds. Williams Obstetrics. 24th ed. New York, NY: McGraw-Hill; 2014:chap 8. US Preventive Services Task Force. Folic acid for ...

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.

Estimated Maternal Pesticide Exposure from Drinking Water and Heart Defects in Offspring

PubMed Central

Kim, Jihye; Swartz, Michael D.; Langlois, Peter H.; Romitti, Paul A.; Weyer, Peter; Mitchell, Laura E.; Ramakrishnan, Anushuya; Malik, Sadia; Lupo, Philip J.; Feldkamp, Marcia L.; Meyer, Robert E.; Winston, Jennifer J.; Reefhuis, Jennita; Blossom, Sarah J.; Bell, Erin; Agopian, A. J.

2017-01-01

Our objective was to examine the relationship between estimated maternal exposure to pesticides in public drinking water and the risk of congenital heart defects (CHD). We used mixed-effects logistic regression to analyze data from 18,291 nonsyndromic cases with heart defects from the Texas Birth Defects Registry and 4414 randomly-selected controls delivered in Texas from 1999 through 2005. Water district-level pesticide exposure was estimated by linking each maternal residential address to the corresponding public water supply district’s measured atrazine levels. We repeated analyses among independent subjects from the National Birth Defects Prevention Study (NBDPS) (1620 nonsyndromic cases with heart defects and 1335 controls delivered from 1999 through 2005). No positive associations were observed between high versus low atrazine level and eight CHD subtypes or all included heart defects combined. These findings should be interpreted with caution, in light of potential misclassification and relatively large proportions of subjects with missing atrazine data. Thus, more consistent and complete monitoring and reporting of drinking water contaminants will aid in better understanding the relationships between pesticide water contaminants and birth defects. PMID:28786932

Estimated Maternal Pesticide Exposure from Drinking Water and Heart Defects in Offspring.

PubMed

Kim, Jihye; Swartz, Michael D; Langlois, Peter H; Romitti, Paul A; Weyer, Peter; Mitchell, Laura E; Luben, Thomas J; Ramakrishnan, Anushuya; Malik, Sadia; Lupo, Philip J; Feldkamp, Marcia L; Meyer, Robert E; Winston, Jennifer J; Reefhuis, Jennita; Blossom, Sarah J; Bell, Erin; Agopian, A J

2017-08-08

Our objective was to examine the relationship between estimated maternal exposure to pesticides in public drinking water and the risk of congenital heart defects (CHD). We used mixed-effects logistic regression to analyze data from 18,291 nonsyndromic cases with heart defects from the Texas Birth Defects Registry and 4414 randomly-selected controls delivered in Texas from 1999 through 2005. Water district-level pesticide exposure was estimated by linking each maternal residential address to the corresponding public water supply district's measured atrazine levels. We repeated analyses among independent subjects from the National Birth Defects Prevention Study (NBDPS) (1620 nonsyndromic cases with heart defects and 1335 controls delivered from 1999 through 2005). No positive associations were observed between high versus low atrazine level and eight CHD subtypes or all included heart defects combined. These findings should be interpreted with caution, in light of potential misclassification and relatively large proportions of subjects with missing atrazine data. Thus, more consistent and complete monitoring and reporting of drinking water contaminants will aid in better understanding the relationships between pesticide water contaminants and birth defects.

Orthopositronium study of positron-irradiation-induced surface defects in alumina powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dauwe, C.; Mbungu-Tsumbu

1992-01-01

Three-quantum-yield measurements and orthopositronium ({ital o}-Ps)-lifetime spectrometry at low temperatures are used to study the interaction of positronium with the surface in fine powders of aluminum oxide. It is found that electron and/or positron irradiation of the specimen induces surface defects which influence the positronium in three ways: (1) A surface positroniumlike bound state is created, (2) the fraction of {ital o}-Ps escaping from the particles is slightly inhibited, and (3) the escaped {ital o}-Ps is quenched into two-quantum decay upon collisions with the surface defects. It is found that the surface Ps state is not populated at the expensemore » of the interparticle Ps. The most likely surface defects are Al{sup 2+} or Al{sup 0} due to the migration of irradiation-induced interstitials. The techniques of long-lifetime spectrometry and of three-quantum-annihilation-rate measurement could be used to study both the diffusion of bulk defects to the surfaces, and the interactions of {ital o}-Ps to surface defects.« less

Lack of periconceptional vitamins or supplements that contain folic acid and diabetes mellitus–associated birth defects

PubMed Central

Correa, Adolfo; Gilboa, Suzanne 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 the risk of birth defects in relation to diabetes mellitus and the lack of use of periconceptional vitamins or supplements that contain folic acid. STUDY DESIGN The National Birth Defects Prevention Study (1997-2004) is a multicenter, population-based case-control study of birth defects (14,721 cases and 5437 control infants). Cases were categorized into 18 types of heart defects and 26 noncardiac birth defects. We estimated odds ratios for independent and joint effects of preexisting diabetes mellitus and a lack of periconceptional use of vitamins or supplements that contain folic acid. RESULTS The pattern of odds ratios suggested an increased risk of defects that are associated with diabetes mellitus in the absence vs the presence of the periconceptional use of vitamins or supplements that contain folic acid. CONCLUSION The lack of periconceptional use of vitamins or supplements that contain folic acid may be associated with an excess risk for birth defects due to diabetes mellitus. PMID:22284962

Study of residue type defect formation mechanism and the effect of advanced defect reduction (ADR) rinse process

NASA Astrophysics Data System (ADS)

Arima, Hiroshi; Yoshida, Yuichi; Yoshihara, Kosuke; Shibata, Tsuyoshi; Kushida, Yuki; Nakagawa, Hiroki; Nishimura, Yukio; Yamaguchi, Yoshikazu

2009-03-01

Residue type defect is one of yield detractors in lithography process. It is known that occurrence of the residue type defect is dependent on resist development process and the defect is reduced by optimized rinsing condition. However, the defect formation is affected by resist materials and substrate conditions. Therefore, it is necessary to optimize the development process condition by each mask level. Those optimization steps require a large amount of time and effort. The formation mechanism is investigated from viewpoint of both material and process. The defect formation is affected by resist material types, substrate condition and development process condition (D.I.W. rinse step). Optimized resist formulation and new rinse technology significantly reduce the residue type defect.

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.

Congenital heart defects in cats: A retrospective study of 162 cats (1996-2013).

PubMed

Tidholm, Anna; Ljungvall, Ingrid; Michal, Jenny; Häggström, Jens; Höglund, Katja

2015-12-01

To study the prevalence and distribution of congenital heart defects in cats presented at two referral centers in Sweden between 1996 and 2013. 162 client-owned cats with congenital heart defects. Case records of cats diagnosed with congenital heart disease were reviewed retrospectively. The overall prevalence of congenital heart disease was 0.2% of the total number of patient cats, and 8% of cats diagnosed with heart disease. A total of 182 heart defects were identified as 16 cats were diagnosed with more than one defect. Ventricular septal defect (VSD) was most prevalent, found in 50% of cats, followed by tricuspid valve dysplasia (11%), pulmonic stenosis (10%), atrial septal defect (10%), aortic stenosis (9%), mitral valve dysplasia (9%), tetralogy of Fallot (5%), patent ductus arteriosus (3%), common atrioventricular canal (2%), and the following defects that each accounted for 0.6% of cats: double chamber right ventricle, double outlet right ventricle, endocardial fibroelastosis, dextroposition of the aorta, persistent right aortic arch, and pulmonary atresia. The prevalence of congenital heart disease was 0.2% of the total number of patient cats, and 8% of cats diagnosed with heart disease. Ventricular septal defect was the most common congenital heart defect in this study. Copyright © 2014 Elsevier B.V. All rights reserved.

Birth defects: Risk factors and consequences

PubMed Central

Oliveira, Camila Ive Ferreira; Fett-Conte, Agnes Cristina

2013-01-01

Birth defects (BDs) or congenital anomalies include all structural and functional alterations in embryonic or fetal development resulting from genetic, environmental or unknown causes, which result in physical and/or mental impairment. BDs occur in about 3% of newborn babies and in most cases of pregnancy loss. BDs are a very complex and heterogeneous group of single or multiple changes that, in most cases, are of unknown etiology. Among the risk factors are advanced maternal and paternal ages, parental consanguinity, teratogenic agents such as infectious agents and drugs, and poor nutrition, in particular folic acid deficiency. One of the consequences of these defects is the high death rate within the first year of life. Information on BDs is becoming increasingly more important throughout the world so that preventive measures can be taken. Knowledge of BDs enables the development of therapeutic and preventive strategies besides adequate genetic counseling. PMID:27625844

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.

Feasibility and Accuracy of Digitizing Edentulous Maxillectomy Defects: A Comparative Study.

PubMed

Elbashti, Mahmoud E; Hattori, Mariko; Patzelt, Sebastian Bm; Schulze, Dirk; Sumita, Yuka I; Taniguchi, Hisashi

The aim of this study was to evaluate the feasibility and accuracy of using an intraoral scanner to digitize edentulous maxillectomy defects. A total of 20 maxillectomy models with two defect types were digitized using cone beam computed tomography. Conventional and digital impressions were made using silicone impression material and a laboratory optical scanner as well as a chairside intraoral scanner. The 3D datasets were analyzed using 3D evaluation software. Two-way analysis of variance revealed no interaction between defect types and impression methods, and the accuracy of the impression methods was significantly different (P = .0374). Digitizing edentulous maxillectomy defect models using a chairside intraoral scanner appears to be feasible and accurate.

Defects in N/Ge coimplanted GaN studied by positron annihilation

NASA Astrophysics Data System (ADS)

Nakano, Yoshitaka; Kachi, Tetsu

2002-01-01

We have applied positron annihilation spectroscopy to study the depth distributions and species of defects in N-, Ge-, and N/Ge-implanted GaN at dosages of 1×1015 cm-2. For all the implanted samples, Ga vacancies introduced by ion-implantation are found to diffuse into much deeper regions of the GaN layers during the implantation and to change into some other vacancy-type defects by the annealing at 1300 °C. In particular, markedly different defects turn out to be newly created in the electrically activated regions for both the Ge- and N/Ge-implanted samples after annealing, indicating that these new defects are probably associated with the presence of the implanted Ge dopant atoms.

Nano-size defects in arsenic-implanted HgCdTe films: a HRTEM study

NASA Astrophysics Data System (ADS)

Bonchyk, O. Yu.; Savytskyy, H. V.; Swiatek, Z.; Morgiel, Y.; Izhnin, I. I.; Voitsekhovskii, A. V.; Korotaev, A. G.; Mynbaev, K. D.; Fitsych, O. I.; Varavin, V. S.; Dvoretsky, S. A.; Marin, D. V.; Yakushev, M. V.

2018-02-01

Radiation damage and its transformation under annealing were studied with bright-field and high-resolution transmission electron microscopy for arsenic-implanted HgCdTe films with graded-gap surface layers. In addition to typical highly defective layers in as-implanted material, a 50 nm-thick sub-surface layer with very low defect density was observed. The main defects in other layers after implantation were dislocation loops, yet after arsenic activation annealing, the dominating defects were single dislocations. Transport (from depth to surface), transformation and annihilation of radiation-induced defects were observed as a result of annealing, with the depth with the maximum defect density decreasing from 110 to 40 nm.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, J. B.; Myers, M. T.; Charnvanichborikarn, S.

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 dependencemore » 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.

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 in this paper, 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 ismore » 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.« less

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

DOE PAGES

Wallace, J. B.; Charnvanichborikarn, S.; Bayu Aji, L. B.; ...

2015-10-06

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 in this paper, 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 ismore » 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.« less

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

NASA Astrophysics Data System (ADS)

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

2015-10-01

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.

Intensity compensation for on-line detection of defects on fruit

NASA Astrophysics Data System (ADS)

Wen, Zhiqing; Tao, Yang

1997-10-01

A machine-vision sorting system was developed that utilizes the difference in light reflectance of fruit surfaces to distinguish the defective and good apples. To accommodate to the spherical reflectance characteristics of fruit with curved surface like apple, a spherical transform algorithm was developed that converts the original image to a non-radiant image without losing defective segments on the fruit. To prevent high-quality dark-colored fruit form being classified into the defective class and increase the defect detection rate for light-colored fruit, an intensity compensation method using maximum propagation was used. Experimental results demonstrated the effectiveness of the method based on maximum propagation and spherical transform for on-line detection of defects on apples.

Use of direct washing of chemical dispense nozzle for defect control

NASA Astrophysics Data System (ADS)

Linnane, Michael; Mack, George; Longstaff, Christopher; Winter, Thomas

2006-03-01

Demands for continued defect reduction in 300mm IC manufacturing are driving process engineers to examine all aspects of the chemical apply process for improvement. Historically, the defect contribution from photoresist apply nozzles has been minimized through a carefully controlled process of "dummy dispenses" to keep the photoresist in the tip "fresh" and remove any solidified material, a preventive maintenance regime involving periodic cleaning or replacing of the nozzles, and reliance on a pool of solvent within the nozzle storage block to keep the photoresist from solidifying at the nozzle tip. The industry standard has worked well for the most part but has limitations in terms of cost effectiveness and absolute defect elimination. In this study, we investigate the direct washing of the chemical apply nozzle to reduce defects seen on the coated wafer. Data is presented on how the direct washing of the chemical dispense nozzle can be used to reduce coating related defects, reduce material costs from the reduction of "dummy dispense", and can reduce equipment downtime related to nozzle cleaning or replacement.

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.

Impact of interstitial iron on the study of meta-stable B-O defects in Czochralski silicon: Further evidence of a single defect

NASA Astrophysics Data System (ADS)

Kim, Moonyong; Chen, Daniel; Abbott, Malcolm; Nampalli, Nitin; Wenham, Stuart; Stefani, Bruno; Hallam, Brett

2018-04-01

We explore the influence of interstitial iron (Fei) on lifetime spectroscopy of boron-oxygen (B-O) related degradation in p-type Czochralski silicon. Theoretical and experimental evidence presented in this study indicate that iron-boron pair (Fe-B) related reactions could have influenced several key experimental results used to derive theories on the fundamental properties of the B-O defect. Firstly, the presence of Fei can account for higher apparent capture cross-section ratios (k) of approximately 100 observed in previous studies during early stages of B-O related degradation. Secondly, the association of Fe-B pairs can explain the initial stage of a two-stage recovery of carrier lifetime with dark annealing after partial degradation. Thirdly, Fei can result in high apparent k values after the permanent deactivation of B-O defects. Subsequently, we show that a single k value can describe the recombination properties associated with B-O defects throughout degradation, that the recovery during dark annealing occurs with a single-stage, and both the fast- and slow-stage B-O related degradation can be permanently deactivated during illuminated annealing. Accounting for the recombination activity of Fei provides further evidence that the B-O defect is a single defect, rather than two separate defects normally attributed to fast-forming recombination centers and slow-forming recombination centers. Implications of this finding for the nature of the B-O defect are also discussed.

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

Associations between maternal periconceptional exposure to secondhand tobacco smoke and major birth defects.

PubMed

Hoyt, Adrienne T; Canfield, Mark A; Romitti, Paul A; Botto, Lorenzo D; Anderka, Marlene T; Krikov, Sergey V; Tarpey, Morgan K; Feldkamp, Marcia L

2016-11-01

While associations between secondhand smoke and a few birth defects (namely, oral clefts and neural tube defects) have been noted in the scientific literature, to our knowledge, there is no single or comprehensive source of population-based information on its associations with a range of birth defects among nonsmoking mothers. We utilized data from the National Birth Defects Prevention Study, a large population-based multisite case-control study, to examine associations between maternal reports of periconceptional exposure to secondhand smoke in the household or workplace/school and major birth defects. The multisite National Birth Defects Prevention Study is the largest case-control study of birth defects to date in the United States. We selected cases from birth defect groups having >100 total cases, as well as all nonmalformed controls (10,200), from delivery years 1997 through 2009; 44 birth defects were examined. After excluding cases and controls from multiple births and whose mothers reported active smoking or pregestational diabetes, we analyzed data on periconceptional secondhand smoke exposure-encompassing the period 1 month prior to conception through the first trimester. For the birth defect craniosynostosis, we additionally examined the effect of exposure in the second and third trimesters as well due to the potential sensitivity to teratogens for this defect throughout pregnancy. Covariates included in all final models of birth defects with ≥5 exposed mothers were study site, previous live births, time between estimated date of delivery and interview date, maternal age at estimated date of delivery, race/ethnicity, education, body mass index, nativity, household income divided by number of people supported by this income, periconceptional alcohol consumption, and folic acid supplementation. For each birth defect examined, we used logistic regression analyses to estimate both crude and adjusted odds ratios and 95% confidence intervals for both

Magnetic resonance imaging study of eye congenital birth defects in mouse model

PubMed Central

Tucker, Zachary; Mongan, Maureen; Meng, Qinghang; Xia, Ying

2017-01-01

Purpose Embryonic eyelid closure is a well-documented morphogenetic episode in mammalian eye development. Detection of eyelid closure defect in humans is a major challenge because eyelid closure and reopen occur entirely in utero. As a consequence, congenital eye defects that are associated with failure of embryonic eyelid closure remain unknown. To fill the gap, we developed a mouse model of defective eyelid closure. This preliminary work demonstrates that the magnetic resonance imaging (MRI) approach can be used for the detection of extraocular muscle abnormalities in the mouse model. Methods Mice with either normal (Map3k1+/−) or defective (Map3k1−/−) embryonic eyelid closure were used in this study. Images of the extraocular muscles were obtained with a 9.4 T high resolution microimaging MRI system. The extraocular muscles were identified, segmented, and measured in each imaging slice using an in-house program. Results In agreement with histological findings, the imaging data show that mice with defective embryonic eyelid closure develop less extraocular muscle than normal mice. In addition, the size of the eyeballs was noticeably reduced in mice with defective embryonic eyelid closure. Conclusions We demonstrated that MRI can potentially be used for the study of extraocular muscle in the mouse model of the eye open-at-birth defect, despite the lack of specificity of muscle group provided by the current imaging resolution. PMID:28848319

Self-expanding platinum-coated nitinol devices for transcatheter closure of atrial septal defect: prevention of nickel release.

PubMed

Lertsapcharoen, Pornthep; Khongphatthanayothin, Apichai; Srimahachota, Suphot; Leelanukrom, Ruenreong

2008-06-01

A variety of nitinol-containing devices for transcatheter closure of atrial septal defects (ASD) has been widely used. However, there is concern about the release of nickel after nitinol device implantation. In this study, a platinum-coated nitinol device was braided from nanoplatinum-coated nitinol wires in order to prevent nickel release. The serum nickel levels before and after device implantation and the 1-year results were evaluated. Thirty-one patients, aged 4-59 years, and weighing 13.7-90.0 kg, underwent transcatheter closure. Blood samples for serum nickel levels were taken before, 1 day, 1 week, 1 month and 3 months after implantation. Twenty-nine (93.6%) patients had a successful implantation. The mean ASD diameter was 19.7 +/- 4.8 mm (range 10-30 mm). Procedure-related complications included transient brachial plexus injury in 1 patient and transient dysrhythmia in 4 patients. All 29 patients had complete closure within 1 month after implantation. The mean serum nickel levels at baseline and at 1 day, 1 week, 1 month and 3 months after implantation were 0.65 +/- 0.28, 0.63 +/- 0.18, 0.67 +/- 0.34, 0.55 +/- 0.16, 0.52 +/- 0.14 ng/ml, respectively. There was no significant difference in serum nickel levels before and after implantation. There were no device-related complications at 1-year follow up. Transcatheter ASD closure using a platinum-coated nitinol device can be performed safely and successfully with good outcomes. Nano-coating of platinum on nitinol wires can prevent nickel release following device implantation.

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.

Optical studies of native defects in π-conjugated donor-acceptor copolymers

NASA Astrophysics Data System (ADS)

Baniya, Sangita; Khanal, Dipak; Lafalce, Evan; You, Wei; Valy Vardeny, Z.

2018-04-01

We used multiple spectroscopies such as photoinduced absorption (PIA), magneto photoinduced absorption, and doping induced absorption for studying native defects in π-conjugated donor-acceptor copolymer chains of benzodithio-phene fluorinated benzotriazole. The PIA spectrum contains characteristic photoinduced absorption bands that are due to polarons and triplet exciton species, whose strengths have different dependencies on the modulation frequency, temperature, and laser excitation, as well as magnetic field response. We found that the native defects in the copolymer chains serve as efficient traps that ionize the photoexcited excitons, thereby generating charge carriers whose characteristic optical properties are similar, but not equal to those of intrachain polarons formed by doping. The native defects density is of the order of 1017 cm-3 indicating that most of the copolymer chains contain native defects upon synthesis; however, this does not preclude their used-for photovoltaic applications.

Antithyroid Drug Use in Pregnancy and Birth Defects: Why Some Studies Find Clear Associations, and Some Studies Report None.

PubMed

Laurberg, Peter; Andersen, Stine Linding

2015-11-01

Rare cases of birth defects after the use of methimazole (MMI) or carbimazole to treat hyperthyroidism in early pregnancy have been reported since 1972, whereas propylthiouracil (PTU) has not been considered teratogenic. Recently, two studies reported birth defects after the use of MMI in early pregnancy to affect 2-4% of exposed children, and one study also found birth defects after the use of PTU. On the other hand, some published studies did not find associations between the use of thionamides and birth defects. The methods used in the two positive and the four negative reports are reviewed. The two positive studies included a sufficient number of children exposed to MMI (n = 1231 and 1097) to evaluate the studied outcomes, whereas the four negative studies included a much lower number of exposed children (n = 73, 108, 30, and 124). Considering PTU, the birth defects observed in one study were in general milder and tended to be diagnosed and registered only when they resulted in complications and led to surgery after one year of age. None of the negative studies has investigated outcomes after one year of age. Studies finding no associations between early pregnancy exposure to antithyroid drugs and birth defects were either not sufficiently powered or did not study outcomes at optimal ages.

Study on clinical application of nano-hydroxyapatite bone in bone defect repair.

PubMed

Zhu, Weimin; Wang, Daping; Xiong, Jianyi; Liu, Jianquan; You, Wei; Huang, Jianghong; Duan, Li; Chen, Jielin; Zeng, Yanjun

2015-01-01

To study the clinical effect of bone defect treated with nano-hydroxyapatite(Nano-HA) artificial bone. From September 2009 to June 2012, 27 cases of bone defect were analyzed retrospectively. The position of bone defect included humerus, radius, ulna, femur, tibia and calcaneus. The range of bone defect was from 0.3 × 1.0 cm to 3 × 6.5 cm. Among them, there were 22 cases with fractures and 5 cases with tumors. All patients were treated with Nano-HA artificial bone. The ability of bone defect repair was evaluated by X-ray exams performed preoperatively and postoperatively. HSS scores were adopted for final evaluation at the latest follow-up. The patients were followed up from 11 to 26 months (average of 18.5 months). No general side effects occurred. X-ray photo showed an integrity interface between Nano-HA and bone. Primary healing was obtained in all cases without any complication. The Nano-HA artificial bone had a good biocompatibility and could be an ideal artificial bone in the reconstruction of bone defect.

Prevalence and Risk of Birth Defects Observed in a Prospective Cohort Study: The Hokkaido Study on Environment and Children's Health.

PubMed

Hanaoka, Tomoyuki; Tamura, Naomi; Ito, Kumiko; Sasaki, Seiko; Araki, Atsuko; Ikeno, Tamiko; Miyashita, Chihiro; Ito, Sachiko; Minakami, Hisanori; Cho, Kazutoshi; Endo, Toshiaki; Baba, Tsuyoshi; Miyamoto, Toshinobu; Sengoku, Kazuo; Kishi, Reiko

2018-03-05

Prevalence rates of all anomalies classified as birth defects, including those identified before the 22nd gestational week, are limited in published reports, including those from the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR). In our birth cohort study, we collected the data for all birth defects after 12 weeks of gestation. Subjects in this study comprised 19,244 pregnant women who visited one of 37 associated hospitals in the Hokkaido Prefecture from 2003 through 2012, and completed follow-up. All birth defects after 12 weeks of gestation, including 55 marker anomalies associated with environmental chemical exposures, were recorded. We examined parental risk factors for birth defects and the association between birth defects and risk of growth retardation. Prevalence of all birth defects was 18.9/1,000 births. The proportion of patients with birth defects delivered between 12 and 21 weeks of gestation was approximately one-tenth of all patients with birth defects. Among those with congenital malformation of the nerve system, 39% were delivered before 22 weeks of gestation. All patients with anencephaly and encephalocele were delivered before 22 weeks of gestation. We observed different patterns of parental risk factors between birth defect cases included in ISBDSR and cases not included. Cases included in ISBDSR were associated with an increased risk of preterm birth. Cases not included in ISBDSR were associated with an increased risk of being small for gestational age at term. Data from our study complemented the data from ICBDSR. We recommend that birth defects not included in ICBDSR also be analyzed to elucidate the etiology of birth defects.

Computational study of hydroxyapatite structures, properties and defects

NASA Astrophysics Data System (ADS)

Bystrov, V. S.; Coutinho, J.; Bystrova, A. V.; Dekhtyar, Yu D.; Pullar, R. C.; Poronin, A.; Palcevskis, E.; Dindune, A.; Alkan, B.; Durucan, C.; Paramonova, E. V.

2015-03-01

Hydroxyapatite (HAp) was studied from a first principle approach using the local density approximation (LDA) method in AIMPRO code, in combination with various quantum mechanical (QM) and molecular mechanical (MM) methods from HypemChem 7.5/8.0. The data obtained were used for studies of HAp structures, the physical properties of HAp (density of electronic states—DOS, bulk modulus etc) and defects in HAp. Computed data confirmed that HAp can co-exist in different phases—hexagonal and monoclinic. Ordered monoclinic structures, which could reveal piezoelectric properties, are of special interest. The data obtained allow us to characterize the properties of the following defects in HAp: O, H and OH vacancies; H and OH interstitials; substitutions of Ca by Mg, Sr, Mn or Se, and P by Si. These properties reveal the appearance of additional energy levels inside the forbidden zone, shifts of the top of the valence band or the bottom of the conduction band, and subsequent changes in the width of the forbidden zone. The data computed are compared with other known data, both calculated and experimental, such as alteration of the electron work functions under different influences of various defects and treatments, obtained by photoelectron emission. The obtained data are very useful, and there is an urgent need for such analysis of modified HAp interactions with living cells and tissues, improvement of implant techniques and development of new nanomedical applications.

Density functional theory study of defects in unalloyed δ-Pu

DOE PAGES

Hernandez, S. C.; Freibert, F. J.; Wills, J. M.

2017-03-19

Using density functional theory, we explore in this paper various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Finally, complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization betweenmore » uranium and plutonium.« less

Density functional theory study of defects in unalloyed δ-Pu

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, S. C.; Freibert, F. J.; Wills, J. M.

Using density functional theory, we explore in this paper various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Finally, complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization betweenmore » uranium and plutonium.« less

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.

Bendectin and birth defects: I. A meta-analysis of the epidemiologic studies.

PubMed

McKeigue, P M; Lamm, S H; Linn, S; Kutcher, J S

1994-07-01

"Bendectin" (Doxylamine/Dicyclomine/Pyridoxine) was widely used for the treatment of nausea and vomiting of pregnancy until 1983, when production was discontinued in the face of lawsuits alleging that the drug caused congenital malformations. We have conducted a meta-analysis of the 16 cohort and 11 case-control studies that report birth defects from Bendectin-exposed pregnancies. This meta-analysis provides an estimate of the relative risk of malformation at birth in association with Bendectin exposure. The pooled estimate of the relative risk of any malformation at birth in association with exposure to Bendectin in the first trimester was 0.95 (95% Cl 0.88 to 1.04). Separate analyses were undertaken for cardiac defects, central nervous system defects, neural tube defects, limb reductions, oral clefts, and genital tract malformations. In these categories, the pooled estimates of relative risk ranged from 0.81 for oral clefts to 1.11 for limb reductions, with all 95% confidence intervals enclosing unity. With the exception of studies for oral clefts and for pyloric stenosis, tests for heterogeneity of association indicated for each table that all studies were estimating the same odds ratio. These studies, as a group, showed no difference in the risk of birth defects between those infants whose mothers had taken Bendectin during the first trimester of pregnancy and those infants whose mothers had not. It is unlikely that Bendectin exposure contributed to the prevalence of congenital malformations in the population.

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.

Folic acid supplementation and the occurrence of congenital heart defects, orofacial clefts, multiple births, and miscarriage.

PubMed

Bailey, Lynn B; Berry, Robert J

2005-05-01

Key research findings relative to the question of whether maternal use of folic acid before and during pregnancy reduces the chance that offspring will be born with a congenital heart defect or an orofacial cleft are reviewed in this paper. Observational studies in general support an association between maternal use of multivitamins containing folic acid and a reduction in the occurrence of congenital heart defects and orofacial clefts. Results from one randomized controlled trial (RCT) provide the strongest evidence that multivitamins prevent congenital heart defects, but this RCT did not provide evidence that multivitamins prevent orofacial clefts. In addition, most observational and interventional studies are not designed to detect an independent effect from folic acid. Early studies suggested that periconceptional multivitamin use was associated with an increased occurrence of both miscarriages and multiple births, which has resulted in a great deal of controversy about the safety of folic acid use during pregnancy. We also review reports that were designed to answer these questions with more definitive data. When more substantial evidence about the effect of periconceptional folic acid on the occurrence of congenital heart defects and orofacial clefts is reported, we will have additional support for promoting folic acid intervention programs. All women capable of becoming pregnant should continue to consume 400 mug/d of folic acid in addition to a healthy diet as advised.

Study of point- and cluster-defects in radiation-damaged silicon

NASA Astrophysics Data System (ADS)

Donegani, Elena M.; Fretwurst, Eckhart; Garutti, Erika; Klanner, Robert; Lindstroem, Gunnar; Pintilie, Ioana; Radu, Roxana; Schwandt, Joern

2018-08-01

Non-ionising energy loss of radiation produces point defects and defect clusters in silicon, which result in a significant degradation of sensor performance. In this contribution results from TSC (Thermally Stimulated Current) defect spectroscopy for silicon pad diodes irradiated by electrons to fluences of a few 1014 cm-2 and energies between 3.5 and 27 MeV for isochronal annealing between 80 and 280∘C, are presented. A method based on SRH (Shockley-Read-Hall) statistics is introduced, which assumes that the ionisation energy of the defects in a cluster depends on the fraction of occupied traps. The difference of ionisation energy of an isolated point defect and a fully occupied cluster, ΔEa, is extracted from the TSC data. For the VOi (vacancy-oxygen interstitial) defect ΔEa = 0 is found, which confirms that it is a point defect, and validates the method for point defects. For clusters made of deep acceptors the ΔEa values for different defects are determined after annealing at 80∘C as a function of electron energy, and for the irradiation with 15 MeV electrons as a function of annealing temperature. For the irradiation with 3.5 MeV electrons the value ΔEa = 0 is found, whereas for the electron energies of 6-27 MeV ΔEa > 0. This agrees with the expected threshold of about 5 MeV for cluster formation by electrons. The ΔEa values determined as a function of annealing temperature show that the annealing rate is different for different defects. A naive diffusion model is used to estimate the temperature dependencies of the diffusion of the defects in the clusters.

Reconstruction of a pelvic floor defect using a pedicled tensor fascia lata flap: a new technique to prevent radiation injury for pediatric patients with advanced pelvic tumors.

PubMed

Ohno, Yasuharu; Tanaka, Katsumi; Kanematsu, Takashi; Noguchi, Mitsuru; Okada, Masahiko; Kamitamari, Akira; Hayashi, Nobuyuki

2008-05-01

In the treatment of pelvic tumors, pelvic floor defects owing to a wide excision tend to increase the occurrence of such morbidities as radiation injury. The reconstruction of these defects would minimize the risk of such morbidities. Authors introduce a new technique for repairing a pelvic floor defect using a tensor fascia lata flap. Two boys, 4 years old and 10 months old, presenting with pelvic rhabdomyosarcoma underwent a tumor extirpation associated with a wide excision of the pelvic organs. After the removal of the tumor, a tensor fascia lata flap was designed on the right thigh. The pedicled rotation flap was subcutaneously elevated, guided to the intraperitoneal cavity, and was fixed to cover the superior aperture of the lesser pelvis. The flaps functioned well, and postoperative radiation therapies consisting of 45 and 41.4 Gy to the lesser pelvic cavity were carried out without any complications. As a result, the necessary postoperative protocol combination therapies could be successfully performed in a timely manner. The pedicled tensor fascia lata flap is considered to be an alternative option for the stable repair of pelvic floor defects to prevent radiation injury.

Insights from Parents about Caring for a Child with Birth Defects

PubMed Central

Lemacks, Jodi; Fowles, Kristin; Mateus, Amanda; Thomas, Kayte

2013-01-01

Birth defects affect 1 in 33 babies. Having a child with a birth defect impacts the whole family. Parents of children who have birth defects face unique challenges and desire to make life better for their kids. They also want to help to prevent birth defects in the future. Some of the challenges parents face involve communication with healthcare professionals, quality of life issues, creating awareness and advocating for research and funding, finding resources and support, and helping teens transition to appropriate, specialized adult care. This paper addresses these issues and their sub-issues, provides examples, and makes suggestions for improvement and research. PMID:23965922

Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

NASA Astrophysics Data System (ADS)

Sellaiyan, S.; Uedono, A.; Sivaji, K.; Janet Priscilla, S.; Sivasankari, J.; Selvalakshmi, T.

2016-10-01

Pure and alkali metal ion (Li, Na, and K)-doped MgO nanocrystallites synthesized by solution combustion technique have been studied by positron lifetime and Doppler broadening spectroscopy methods. Positron lifetime analysis exhibits four characteristic lifetime components for all the samples. Doping reduces the Mg vacancy after annealing to 800 °C. It was observed that Li ion migrates to the vacancy site to recover Mg vacancy-type defects, reducing cluster vacancies and micropores. For Na- and K-doped MgO, the aforementioned defects are reduced and immobile at 800 °C. Coincidence Doppler broadening studies show the positron trapping sites as vacancy clusters. The decrease in the S parameter is due to the particle growth and reduction in the defect concentration at 800 °C. Photoluminescence study shows an emission peak at 445 nm and 498 nm, associated with F2 2+ and recombination of higher-order vacancy complexes. Further, annealing process is likely to dissociate F2 2+ to F+ and this F+ is converted into F centers at 416 nm.

First-Principles Study of Native Defects in TlBr: Carrier Trapping, Compensation, and Polarization Phemomenon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Mao-Hua

2010-01-01

First-principles calculations are carried out to study the native defect properties in TlBr. Three important results emerge: (1) the native defects are benign in terms of electron trapping because the low-energy defects do not induce electron traps; (2) the dominant defects in nearly stoichiometric TlBr are Schottky defects that pin the Fermi level near the midgap, leading to high resistivity; and (3) the calculated low diffusion barriers for several native defects show that ionic conductivity can occur at room temperature. The important impacts of these material properties on the room-temperature radiation detection using TlBr are discussed.

First-principles study of native defects in TlBr: Carrier trapping, compensation, and polarization phemomenon

NASA Astrophysics Data System (ADS)

Du, Mao-Hua

2010-09-01

First-principles calculations are carried out to study the native defect properties in TlBr. Three important results emerge: (1) the native defects are benign in terms of electron trapping because the low-energy defects do not induce electron traps; (2) the dominant defects in nearly stoichiometric TlBr are Schottky defects that pin the Fermi level near the midgap, leading to high resistivity; and (3) the calculated low diffusion barriers for several native defects show that ionic conductivity can occur at room temperature. The important impacts of these material properties on the room-temperature radiation detection using TlBr are discussed.

A tungsten-rhenium interatomic potential for point defect studies

NASA Astrophysics Data System (ADS)

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

2018-05-01

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures in the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancies and self-interstitial defects sufficiently accurately and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).

EPIDEMIOLOGY STUDY OF BIRTH DEFECTS AND DISINFECTION BYPRODUCTS

EPA Science Inventory

Birth defects are the leading cause of infant mortality in the US, accounting for more than 20% of all infant deaths. In addition, birth defects are the fifth leading cause of years of potential lief life lost and contribute substantially to childhood morbidity and long-term disa...

A study of process-related electrical defects in SOI lateral bipolar transistors fabricated by ion implantation

NASA Astrophysics Data System (ADS)

Yau, J.-B.; Cai, J.; Hashemi, P.; Balakrishnan, K.; D'Emic, C.; Ning, T. H.

2018-04-01

We report a systematic study of process-related electrical defects in symmetric lateral NPN transistors on silicon-on-insulator (SOI) fabricated using ion implantation for all the doped regions. A primary objective of this study is to see if pipe defects (emitter-collector shorts caused by locally enhanced dopant diffusion) are a show stopper for such bipolar technology. Measurements of IC-VCE and Gummel currents in parallel-connected transistor chains as a function of post-fabrication rapid thermal anneal cycles allow several process-related electrical defects to be identified. They include defective emitter-base and collector-base diodes, pipe defects, and defects associated with a dopant-deficient region in an extrinsic base adjacent its intrinsic base. There is no evidence of pipe defects being a major concern in SOI lateral bipolar transistors.

An investigation on defect-generation conditions in immersion lithography

NASA Astrophysics Data System (ADS)

Tomita, Tadatoshi; Shimoaoki, Takeshi; Enomoto, Masashi; Kyoda, Hideharu; Kitano, Junichi; Suganaga, Toshifumi

2006-03-01

As a powerful candidate for a lithography technique that can accommodate the scaling-down of semiconductors, 193-nm immersion lithography-which realizes a high numerical aperture (NA) and uses deionized water as the medium between the lens and wafer in the exposure system-has been developing at a rapid pace and has reached the stage of practical application. In regards to defects that are a cause for concern in the case of 193-nm immersion lithography, however, many components are still unclear and many problems remain to be solved. It has been pointed out, for example, that in the case of 193-nm immersion lithography, immersion of the resist film in deionized water during exposure causes infiltration of moisture into the resist film, internal components of the resist dissolve into the deionized water, and residual water generated during exposure affects post-processing. Moreover, to prevent this influence of directly immersing the resist in de-ionized water, application of a protective film is regarded as effective. However, even if such a film is applied, it is still highly likely that the above-mentioned defects will still occur. Accordingly, to reduce these defects, it is essential to identify the typical defects occurring in 193-nm immersion lithography and to understand the condition for generation of defects by using some kinds of protective films and resist materials. Furthermore, from now onwards, with further scaling down of semiconductors, it is important to maintain a clear understanding of the relation between defect-generation conditions and critical dimensions (CD). Aiming to extract typical defects occurring in 193-nm immersion lithography, the authors carried out a comparative study with dry exposure lithography, thereby confirming several typical defects associated with immersion lithography. We then investigated the conditions for generation of defects in the case of some kinds of protective films. In addition to that, by investigating the defect

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.

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.

Microcomputed tomographic and histomorphometric analyses of novel titanium mesh membranes for guided bone regeneration: a study in rat calvarial defects.

PubMed

Rakhmatia, Yunia Dwi; Ayukawa, Yasunori; Furuhashi, Akihiro; Koyano, Kiyoshi

2014-01-01

The objective of this study was to evaluate the optimal thickness and porosity of novel titanium mesh membranes to enhance bone augmentation, prevent soft tissue ingrowth, and prevent membrane exposure. Six types of novel titanium meshes with different thicknesses and pore sizes, along with three commercially available membranes, were used to cover surgically created calvarial defects in 6-week-old Sprague-Dawley rats. The animals were killed after 4 or 8 weeks. Microcomputed tomographic analyses were performed to analyze the three-dimensional bone volume and bone mineral density. Soft tissue ingrowth was also evaluated histologically and histomorphometrically. The novel titanium membranes used in this study were as effective at augmenting bone in the rat calvarial defect model as the commercially available membranes. The greatest bone volume was observed on 100-μm-thick membranes with larger pores, although these membranes promoted growth of bone with lower mineral density. Soft tissue ingrowth when 100-μm membranes were used was increased at 4 weeks but decreased again by 8 weeks to a level not statistically significantly different from other membranes. Membrane thickness affects the total amount of new bone formation, and membrane porosity is an essential factor for guided bone regeneration, especially during the initial healing period, although the final bone volume obtained is essentially the same. Newly developed titanium mesh membranes of 100 μm in thickness and with large pores appear to be optimal for guided bone regeneration.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uedono, Akira; Yoshihara, Nakaaki; Mizushima, Yoriko

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 ofmore » 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.« less

Dangling bond defects in SiC: An ab initio study

NASA Astrophysics Data System (ADS)

Tuttle, Blair R.

2018-01-01

We report first-principles microscopic calculations of the properties of defects with dangling bonds in crystalline 3 C -SiC. Specifically, we focus on hydrogenated Si and C vacancies, divacancies, and multivacancies. The latter is a generic model for an isolated dangling bond within a bulk SiC matrix. Hydrogen serves to passivate electrically active defects to allow the isolation of a single dangling-bond defect. We used hybrid density-functional methods to determine energetics and electrical activity. The present results are compared to previous 3 C -SiC calculations and experiments. Finally, we identify homopolar carbon dangling-bond defects as the leakage causing defects in nanoporous SiC alloys.

First-principles study of defects and phase transition in UO(2).

PubMed

Yu, Jianguo; Devanathan, Ram; Weber, William J

2009-10-28

Defect properties and phase transition in UO(2) have been studied from first principles by the all-electron projector-augmented-wave (PAW) method. The generalized gradient approximation with empirical self-interaction correction, (GGA)+U, formalism has been used to account for the strong on-site Coulomb repulsion among the localized U 5f electrons. The Hubbard parameter U(eff), magnetic ordering, chemical potential and heat of formation have been systematically examined. By choosing an appropriate U(eff) = 3.0 eV it is possible to consistently describe structural properties of UO(2) and model the phase transition processes. The phase transition pressure for UO(2) is about 20 GPa, which is less than the experimental value of 42 GPa but better than the LDA+U value of 7.8 GPa. Meanwhile our results for the formation energies of intrinsic defects partly confirm earlier calculations for the intrinsic charge neutral defects but reveal large variations depending on the determination of the chemical potential and whether the environment is O-rich or U-rich. Moreover, the results for extrinsic defects of Xe, which are representative of mobile insoluble fission product in UO(2), are consistent with experimental data in which Xe prefers to be trapped by Schottky defects.

[Experimental study on long-term prevention effect of chitosan electrospun membrane on cerebrospinal fluid leakage].

PubMed

Guo, Xingfeng; Hou, Chunlin; Dou, Yuandong; Lin, Ye; Lei, Deqiao

2014-08-01

To study the long-term prevention effect of self-developed chitosan electrospun membrane on cerebrospinal fluid leakage. Twenty-five healthy adult New Zealand rabbits were selected to prepare the bilateral dural defect (0.8 cem x 0.8 cm in size) via midline incision of head. Defect of the right was repaired with chitosan electrospun membrane as the experimental group; defect of the left was not repaired as the control group. At 2-16 weeks after operation, one rabbit was sacrificed for the general observation of inflammatory response surrounding bone window and absorption of chitosan electrospun membrane; at 3 and 6 weeks after operation, 5 rabbits were sacrificed for sampling to observe histological change and collagen expression by_HE and Masson staining, and to measure the expressions of epidermal growth factor receptor (EGFR) and basic fibroblast growth factor (bFGF) by immunohistochemical staining. No inflammatory reaction of swelling, exudation, and sppuration appeared in the skin and subcutaneous tissue after operation in 2 groups. There was no adhesion around the chitosan electrospun membrane, and new fiber membrane formed under the chitosan electrospun membrane in the experimental group; no cerebrospinal fluid leakage happened; the chitosan electrospun membrane was gradually degraded with time, and was completely absorbed at 16 weeks. There was uneven scar around the dural detect in control group. Histological observation showed less inflammatory cell infiltration in the experimental group, showing significant difference in the number of inflammatory cells compared with control group at 3, 6 weeks (P < 0.05); capillary, granulation tissue and collagen fiber massively proliferated; collagen fiber arranged in line, and there was a clear borderline between chitosan electrospurn membrane and adjacent collagen fiber. The immunohistochemical staining showed that there were high expressions of bFGF and EGFR in the experimental group, and low expressions of b

A study of phase defect measurement on EUV mask by multiple detectors CD-SEM

NASA Astrophysics Data System (ADS)

Yonekura, Isao; Hakii, Hidemitsu; Morisaki, Shinya; Murakawa, Tsutomu; Shida, Soichi; Kuribara, Masayuki; Iwai, Toshimichi; Matsumoto, Jun; Nakamura, Takayuki

2013-06-01

We have studied MVM (Multi Vision Metrology) -SEM® E3630 to measure 3D shape of defects. The four detectors (Detector A, B, C and D) are independently set up in symmetry for the primary electron beam axis. Signal processing of four direction images enables not only 2D (width) measurement but also 3D (height) measurement. At last PMJ, we have investigated the relation between the E3630's signal of programmed defect on MoSi-HT and defect height measured by AFM (Atomic Force Microscope). It was confirmed that height of integral profile by this tool is correlated with AFM. It was tested that E3630 has capability of observing multilayer defect on EUV. We have investigated correlation with AFM of width and depth or height of multilayer defect. As the result of observing programmed defects, it was confirmed that measurement result by E3630 is well correlated with AFM. And the function of 3D view image enables to show nm order defect.

Attaining human dignity for people with birth defects: a historical perspective.

PubMed

Christianson, Arnold L

2013-10-11

People with birth defects have been stigmatised, marginalised and discriminated against for millennia, diminishing their human dignity and abrogating their human rights. Beginning with the United Nations Universal Declaration of Human Rights, promulgated in 1947, the circumstances in which human dignity in healthcare for people with birth defects could be achieved arose, and this was accomplished over the next 65 years through the insight, hard work and dedication of a select group of people and organisations. In 2010 the World Health Organization prioritised services for the care and prevention of birth defects, particularly in middle- and low-income countries. Translating what has been achieved into human rights in healthcare for people with birth defects is the next objective. 

Anti-site defected MoS2 sheet for catalytic application

NASA Astrophysics Data System (ADS)

Sharma, Archana; Husain, Mushahid; Khan, Mohd. Shahid

2018-04-01

To prevent harmful and poisonous CO gas molecules, catalysts are needed for converting them into benign substances. Density functional theory (DFT) calculations have been used to investigate CO oxidation on the surface of MoS2 monolayer with Mo atom embedded at S-vacancy site (anti-site defect). The stronger interaction between Mo metal with O2 molecule as compared with CO molecule suggests high catalytic activity. The complete oxidation of CO is studied in a two-step procedure using Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms with a low overall energy barrier of 0.35 eV. Creation of anti-site defect makes the surface of MoS2 nanosheet catalytically active for the CO oxidation to take place.

First principles study of intrinsic defects in hexagonal tungsten carbide

NASA Astrophysics Data System (ADS)

Kong, Xiang-Shan; You, Yu-Wei; Xia, J. H.; Liu, C. S.; Fang, Q. F.; Luo, G.-N.; Huang, Qun-Ying

2010-11-01

The characteristics of intrinsic defects are important for the understanding of self-diffusion processes, mechanical strength, brittleness, and plasticity of tungsten carbide, which are present in the divertor of fusion reactors. Here, we use first-principles calculations to investigate the stability of point defects and their complexes in tungsten carbide. Our results confirm that the defect formation energies of carbon are much lower than that of tungsten and reveal the carbon vacancy to be the dominant defect in tungsten carbide. The C sbnd C dimer configuration along the dense a direction is the most stable configuration of carbon interstitial defect. The results of carbon defect diffusion show that the carbon vacancy stay for a wide range of temperature because of extremely high diffusion barriers, while carbon interstitial migration is activated at lower temperatures for its considerably lower activation energy. Both of them prefer to diffusion in carbon basal plane.

Investigation of defect modes in a defective photonic crystal with a semiconductor metamaterial defect

NASA Astrophysics Data System (ADS)

Wu, Meng-Ru; Wu, Chien-Jang; Chang, Shoou-Jinn

2014-11-01

In this work, we theoretically investigate the properties of defect modes in a defective photonic crystal containing a semiconductor metamaterial defect. We consider the structure, (LH)N/DP/(LH)N, where N and P are respectively the stack numbers, L is SiO2, H is InP, and defect layer D is a semiconductor metamaterial composed of Al-doped ZnO (AZO) and ZnO. It is found that, within the photonic band gap, the number of defect modes (transmission peaks) will decrease as the defect thickness increases, in sharp contrast to the case of using usual dielectric defect. The peak height and position can be changed by the variation in the thickness of defect layer. In the angle-dependent defect mode, its position is shown to be blue-shifted as the angle of incidence increases for both TE and TM waves. The analysis of defect mode provides useful information for the design of tunable transmission filter in semiconductor optoelectronics.

Pathophysiology of Corneal Scarring in Persistent Epithelial Defects After PRK and Other Corneal Injuries.

PubMed

Wilson, Steven E; Medeiros, Carla S; Santhiago, Marcony R

2018-01-01

To analyze corneal persistent epithelial defects that occurred at 3 to 4 weeks after -4.50 diopter (D) photorefractive keratectomy (PRK) in rabbits and apply this pathophysiology to the treatment of persistent epithelial defects that occur after any corneal manipulations or diseases. Two of 168 corneas that had -4.50 D PRK to study epithelial basement membrane regeneration developed spontaneous persistent epithelial defects that did not heal at 3 weeks after PRK. These were studied with slit-lamp photographs, immunohistochemistry for the myofibroblast marker alpha-smooth muscle actin (α-SMA), and transmission electron microscopy. Myofibroblasts developed at the stromal surface within the persistent epithelial defect and for a short distance peripheral to the leading edge of the epithelium. No normal epithelial basement membrane was detectable within the persistent epithelial defect or for up to 0.3 mm behind the leading edge of the epithelium, although epithelial basement membrane had normally regenerated in other areas of the zone ablated by an excimer laser where the epithelium healed promptly. A persistent epithelial defect in the cornea results in the development of myofibroblasts and disordered extracellular matrix produced by these cells that together cause opacity within, and a short distance beyond, the persistent epithelial defect. Clinicians should treat persistent epithelial defects within 10 days of non-closure of the epithelium to facilitate epithelial healing to prevent long-term stromal scarring (fibrosis). [J Refract Surg. 2018;34(1):59-64.]. Copyright 2018, SLACK Incorporated.

A somatic T15091C mutation in the Cytb gene of mouse mitochondrial DNA dominantly induces respiration defects.

PubMed

Hayashi, Chisato; Takibuchi, Gaku; Shimizu, Akinori; Mito, Takayuki; Ishikawa, Kaori; Nakada, Kazuto; Hayashi, Jun-Ichi

2015-08-07

Our previous studies provided evidence that mammalian mitochondrial DNA (mtDNA) mutations that cause mitochondrial respiration defects behave in a recessive manner, because the induction of respiration defects could be prevented with the help of a small proportion (10%-20%) of mtDNA without the mutations. However, subsequent studies found the induction of respiration defects by the accelerated accumulation of a small proportion of mtDNA with various somatic mutations, indicating the presence of mtDNA mutations that behave in a dominant manner. Here, to provide the evidence for the presence of dominant mutations in mtDNA, we used mouse lung carcinoma P29 cells and examined whether some mtDNA molecules possess somatic mutations that dominantly induce respiration defects. Cloning and sequence analysis of 40-48 mtDNA molecules from P29 cells was carried out to screen for somatic mutations in protein-coding genes, because mutations in these genes could dominantly regulate respiration defects by formation of abnormal polypeptides. We found 108 missense mutations existing in one or more of 40-48 mtDNA molecules. Of these missense mutations, a T15091C mutation in the Cytb gene was expected to be pathogenic due to the presence of its orthologous mutation in mtDNA from a patient with cardiomyopathy. After isolation of many subclones from parental P29 cells, we obtained subclones with various proportions of T15091C mtDNA, and showed that the respiration defects were induced in a subclone with only 49% T15091C mtDNA. Because the induction of respiration defects could not be prevented with the help of the remaining 51% mtDNA without the T15091C mutation, the results indicate that the T15091C mutation in mtDNA dominantly induced the respiration defects. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of Stone-Wales and vacancy defects in atomic-scale friction on defective graphite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao-Yu; Key Laboratory of Hubei Province for Water Jet Theory and New Technology, Wuhan University, Wuhan 430072; Wu, RunNi

2014-05-05

Graphite is an excellent solid lubricant for surface coating, but its performance is significantly weakened by the vacancy or Stone-Wales (SW) defect. This study uses molecular dynamics simulations to explore the frictional behavior of a diamond tip sliding over a graphite which contains a single defect or stacked defects. Our results suggest that the friction on defective graphite shows a strong dependence on defect location and type. The 5-7-7-5 structure of SW defect results in an effectively negative slope of friction. For defective graphite containing a defect in the surface, adding a single vacancy in the interior layer will decreasemore » the friction coefficients, while setting a SW defect in the interior layer may increase the friction coefficients. Our obtained results may provide useful information for understanding the atomic-scale friction properties of defective graphite.« less

Radiation damage and defect behavior in proton irradiated lithium-counterdoped n+p silicon solar cells

NASA Technical Reports Server (NTRS)

Stupica, John; Goradia, Chandra; Swartz, Clifford K.; Weinberg, Irving

1987-01-01

Two lithium-counterdoped n+p silicon solar cells with different lithium concentrations were irradiated by 10-MeV protons. Cell performance was measured as a function of fluence, and it was found that the cell with the highest concentration of lithium had the highest radiation resistance. Deep level transient spectroscopy which showed two deep level defects that were lithium related. Relating the defect energy levels obtained from this study with those from earlier work using 1-MeV electron irradiation shows no correlation of the defect energy levels. There is one marked similarity: the absence of the boron-interstitial-oxygen-interstitial defect. This consistency strengthens the belief that lithium interacts with oxygen to prevent the formation of the boron interstitial-oxygen interstitial defect. The results indicate that, in general, addition of lithium in small amounts to the p-base of a boron doped silicon solar cell such that the base remains p-type, tends to increase the radiation resistance of the cell.

Evaluation of Dentin Defect Formation during Retreatment with Hand and Rotary Instruments: A Micro-CT Study.

PubMed

Yilmaz, Ayca; Helvacioglu-Yigit, Dilek; Gur, Cansu; Ersev, Handan; Kiziltas Sendur, Gullu; Avcu, Egemen; Baydemir, Canan; Abbott, Paul Vincent

2017-01-01

The purpose of this study was to compare the incidence and longitudinal propagation of dentin defects after gutta-percha removal with hand and rotary instruments using microcomputed tomography. Twenty mandibular incisors were prepared using the balanced-force technique and scanned in a 19.9  μ m resolution. Following filling with the lateral compaction technique, gutta-percha was removed with ProTaper Universal Retreatment (PTUR) or hand instruments. After rescanning, a total of 24,120 cross-sectional images were analyzed. The numbers, types, and longitudinal length changes of defects were recorded. Defects were observed in 36.90% of the cross sections. A total of 73 defects were comprised of 87.67% craze lines, 2.73% partial cracks, and 9.58% fractures. No significant difference in terms of new defect formation was detected between the retreatment groups. The apical and middle portions of the roots had more dentin defects than the coronal portions. Defects in three roots of the PTUR instrument group increased in length. Under the conditions of this in vitro study, gutta-percha removal seemed to not increase the incidence of dentin defect formation, but the longitudinal defect propagation finding suggests possible cumulative dentinal damage due to additional endodontic procedures. Hand and rotary instrumentation techniques caused similar dentin defect formation during root canal retreatment.

Synthetic Defects for Vibrothermography

NASA Astrophysics Data System (ADS)

Renshaw, Jeremy; Holland, Stephen D.; Thompson, R. Bruce; Eisenmann, David J.

2010-02-01

Synthetic defects are an important tool used for characterizing the performance of nondestructive evaluation techniques. Viscous material-filled synthetic defects were developed for use in vibrothermography (also known as sonic IR) as a tool to improve inspection accuracy and reliability. This paper describes how the heat-generation response of these VMF synthetic defects is similar to the response of real defects. It also shows how VMF defects can be applied to improve inspection accuracy for complex industrial parts and presents a study of their application in an aircraft engine stator vane.

Retrospective study of congenital heart defects in 151 dogs.

PubMed

Tidholm, A

1997-03-01

The case records of 151 dogs diagnosed with congenital heart disease were reviewed retrospectively. The most common defect was aortic stenosis, accounting for 35 per cent of all cases, followed by pulmonic stenosis (20 per cent), ventricular septal defect (12 per cent), patent ductus arteriosus (11 per cent), mitral valve dysplasia (8 per cent), tricuspid valve dysplasia (7 per cent), endocardial fibroelastosis (1.9 per cent) and tetralogy of Fallot (0.6 per cent). Fifty-one breeds were represented, with golden retrievers, German shepherd dogs and boxers predominating. No overall sex predilection was obvious. Seventy-five per cent of the dogs were asymptomatic at presentation. The defects most often associated with presenting symptoms, such as dyspnoea, syncope, ascites, failure to grow and depression, were mitral valve dysplasia, atrial septal defect, tricuspid valve dysplasia and endocardial fibroelastosis. The latter presented with the most severe signs of heart failure. In some cases of aortic stenosis and pulmonic stenosis, where the defect could not be accurately visualised with two-dimensional echocardiography, Doppler echocardiographic examination was needed for definitive diagnosis.

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

Birth defects after use of antithyroid drugs in early pregnancy: a Swedish nationwide study.

PubMed

Andersen, Stine Linding; Lönn, Stefan; Vestergaard, Peter; Törring, Ove

2017-10-01

Antithyroid drugs (ATDs) may have teratogenic effects, but more evidence is needed on the risk and types of birth defects after the use of methimazole (MMI) and propylthiouracil (PTU). This study aimed to evaluate the association between the use of ATDs in early pregnancy and birth defects. Swedish nationwide register-based cohort study. The study included 684 340 children live-born in Sweden from 2006 to 2012. Exposure groups defined by maternal ATD use in early pregnancy were MMI ( n  = 162); PTU ( n  = 218); MMI and PTU ( n  = 66); ATD before or after, but not in pregnancy ( n  = 1551) and non-exposed (never ATD ( n  = 682 343)). Outcome was cumulative incidence of birth defects diagnosed before two years of age. The cumulative incidence of birth defects was not significantly different in children exposed to MMI (6.8%, P  = 0.6) or PTU (6.4%, P  = 0.4) vs non-exposed (8.0%). For subtypes of birth defects, MMI was associated with an increased incidence of septal heart defects ( P  = 0.02). PTU was associated with ear ( P  = 0.005) and obstructive urinary system malformations ( P  = 0.006). A case of choanal atresia was observed after exposure to both MMI and PTU. The incidence of birth defects in children born to mothers who received ATD before or after, but not in pregnancy, was 8.8% and not significantly different from non-exposed ( P  = 0.3), MMI exposed ( P  = 0.4) or PTU exposed ( P  = 0.2). MMI and PTU were associated with subtypes of birth defects previously reported, but the frequency of ATD exposure in early pregnancy was low and severe malformations described in the MMI embryopathy were rarely observed. © 2017 European Society of Endocrinology.

A tungsten-rhenium interatomic potential for point defect studies

DOE PAGES

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

2018-05-28

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method (EAM) interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures inmore » the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancy and self-interstitial defects sufficiently accurately, and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).« less

A tungsten-rhenium interatomic potential for point defect studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method (EAM) interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures inmore » the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancy and self-interstitial defects sufficiently accurately, and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).« less

Assessing bottled water nitrate concentrations to evaluate total drinking water nitrate exposure and risk of birth defects.

PubMed

Weyer, Peter J; Brender, Jean D; Romitti, Paul A; Kantamneni, Jiji R; Crawford, David; Sharkey, Joseph R; Shinde, Mayura; Horel, Scott A; Vuong, Ann M; Langlois, Peter H

2014-12-01

Previous epidemiologic studies of maternal exposure to drinking water nitrate did not account for bottled water consumption. The objective of this National Birth Defects Prevention Study (NBDPS) (USA) analysis was to assess the impact of bottled water use on the relation between maternal exposure to drinking water nitrate and selected birth defects in infants born during 1997-2005. Prenatal residences of 1,410 mothers reporting exclusive bottled water use were geocoded and mapped; 326 bottled water samples were collected and analyzed using Environmental Protection Agency Method 300.0. Median bottled water nitrate concentrations were assigned by community; mothers' overall intake of nitrate in mg/day from drinking water was calculated. Odds ratios for neural tube defects, limb deficiencies, oral cleft defects, and heart defects were estimated using mixed-effects models for logistic regression. Odds ratios (95% CIs) for the highest exposure group in offspring of mothers reporting exclusive use of bottled water were: neural tube defects [1.42 (0.51, 3.99)], limb deficiencies [1.86 (0.51, 6.80)], oral clefts [1.43 (0.61, 3.31)], and heart defects [2.13, (0.87, 5.17)]. Bottled water nitrate had no appreciable impact on risk for birth defects in the NBDPS.

Assessing bottled water nitrate concentrations to evaluate total drinking water nitrate exposure and risk of birth defects

PubMed Central

Weyer, Peter J.; Brender, Jean D.; Romitti, Paul A.; Kantamneni, Jiji R.; Crawford, David; Sharkey, Joseph R.; Shinde, Mayura; Horel, Scott A.; Vuong, Ann M.; Langlois, Peter H.

2016-01-01

Previous epidemiologic studies of maternal exposure to drinking water nitrate did not account for bottled water consumption. The objective of this National Birth Defects Prevention Study (NBDPS) (USA) analysis was to assess the impact of bottled water use on the relation between maternal exposure to drinking water nitrate and selected birth defects in infants born during 1997–2005. Prenatal residences of 1,410 mothers reporting exclusive bottled water use were geocoded and mapped; 326 bottled water samples were collected and analyzed using Environmental Protection Agency Method 300.0. Median bottled water nitrate concentrations were assigned by community; mothers’ overall intake of nitrate in mg/day from drinking water was calculated. Odds ratios for neural tube defects, limb deficiencies, oral cleft defects, and heart defects were estimated using mixed-effects models for logistic regression. Odds ratios (95% CIs) for the highest exposure group in offspring of mothers reporting exclusive use of bottled water were: neural tube defects [1.42 (0.51, 3.99)], limb deficiencies [1.86 (0.51, 6.80)], oral clefts [1.43 (0.61, 3.31)], and heart defects [2.13, (0.87, 5.17)]. Bottled water nitrate had no appreciable impact on risk for birth defects in the NBDPS. PMID:25473985

Improving surveillance for injuries associated with potential motor vehicle safety defects

PubMed Central

Whitfield, R; Whitfield, A

2004-01-01

Objective: To improve surveillance for deaths and injuries associated with potential motor vehicle safety defects. Design: Vehicles in fatal crashes can be studied for indications of potential defects using an "early warning" surveillance statistic previously suggested for screening reports of adverse drug reactions. This statistic is illustrated with time series data for fatal, tire related and fire related crashes. Geographic analyses are used to augment the tire related statistics. Results: A statistical criterion based on the Poisson distribution that tests the likelihood of an expected number of events, given the number of events that actually occurred, is a promising method that can be readily adapted for use in injury surveillance. Conclusions: Use of the demonstrated techniques could have helped to avert a well known injury surveillance failure. This method is adaptable to aid in the direction of engineering and statistical reviews to prevent deaths and injuries associated with potential motor vehicle safety defects using available databases. PMID:15066972

HOW to Recognize Hazardous Defects in Trees

Treesearch

Minnesota Department of Natural Resources; USDA Forest Service

1996-01-01

Trees add to our enjoyment of outdoor experiences whether in forests, parks, or urban landscapes. Too often, we are unaware of the risks associated with defective trees, which can cause personal injury and property damage. Interest in hazard tree management has increased in recent years due to safety and liability concerns resulting from preventable accidents....

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.

Study of defects in TlBr, InI as potential semiconductor radiation detectors

NASA Astrophysics Data System (ADS)

Biswas, Koushik; Du, Mao-Hua

2011-03-01

Group III-halides such as TlBr and InI are receiving considerable attention for application in room temperature radiation detector devices. It is however, essential that these detector materials have favorable defect properties which enable good carrier transport when operating under an external bias voltage. We have studied the properties of native defects of InI and Tlbr and several important results emerge: (1) Schottky defects are the dominant low-energy defects in both materials that can potentially pin the Fermi level close to midgap, leading to high resistivity; (2) native defects in TlBr are benign in terms of electron trapping. However, anion-vacancy in InI induces a deep electron trap similar to the F -centers in alkali halides. This can reduce electron mobility-lifetime product in InI; (3) low diffusion barriers of vacancies and ionic conductivity could be responsible for the observed polarization phenomenon in both materials at room temperature. U.S. DOE Office of Nonproliferation Research and Development NA22.

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.

Defect studies in copper-based p-type transparent conducting oxides

NASA Astrophysics Data System (ADS)

Ameena, Fnu

Among other intrinsic open-volume defects, copper vacancy (VCu) has been theoretically identified as the major acceptor in p-type Cu-based semiconducting transparent oxides, which has potential as low-cost photovoltaic absorbers in semi-transparent solar cells. A series of positron annihilation experiments with pure Cu, Cu2O, and CuO presented strong presence of VCu and its complexes in the copper oxides. The lifetime data also showed that the density of VCu was becoming higher as the oxidation state of Cu increased which was consistent with the decrease in the formation energy of VCu. Doppler broadening measurements further indicated that electrons with low momentum made more contribution to the contributed as pure Cu oxidizes to copper oxides. The metastable defects are known to be generated in Cu2O upon illumination and it has been known to affect the performance of Cu2O-based hetero-junctions used in solar cells. The metastable effect was studied using positron annihilation lifetime spectroscopy and its data showed the change in the defect population upon light exposure and the minimal effect of light-induced electron density increase in the bulk of materials to the average lifetime of the positrons. The change in the defect population is concluded to be related to the dissociation and association of VCu -- V Cu complexes. For example, the shorter lifetime under light was ascribed to the annihilation with smaller size vacancies, which explains the dissociation of the complexes with light illumination. Doppler broadening of the annihilation was independent of light illumination, which suggested that the chemical nature of the defects remained without change upon their dissociation and association -- only the size distribution of copper vacancies varied. The delafossite metal oxides, CuMIIIO2 are emerging wide-bandgap p-type semiconductors. In this research, the formation energies of structural vacancies are calculated using Van Vechten cavity model as an attempt

Theoretical study of native point defects in strained-layer superlattice systems

NASA Astrophysics Data System (ADS)

Krishnamurthy, S.; Yu, Zhi Gang

2018-04-01

We developed a theoretical approach that employs first-principles Hamiltonians, tight-binding Hamiltonians, and Green's function techniques to obtain energy levels arising from native point defects (NPDs) in InAs-GaSb and InAs-InAs1-xSbx strained layer superlattice (SLS) systems. In InAs and GaSb regions, we considered four types of NPDs—anion vacancy, cation vacancy, anion anti-site, and cation anti-site—as well as isoelectronic substitution at anion sites (Sb at the As site and As at the Sb site). Additionally, we considered three types of defects—the cation at the second anion site, the second anion at the cation site, and second anion vacancy—in the InAs1-xSbx alloy region of the SLS. For a selected few designs, we studied NPDs both in the bulk region and near the interfaces of the SLS. We have considered 12 designs of InAs-GaSb systems and two designs of InAs-InAs0.7Sb0.3 systems lattice-matched to the GaSb substrate. The calculated defect levels not only agreed well with available measurements, but also revealed the connection between mid-gap levels and specific NPDs. We further calculated defect formation energies both in compounds and in all superlattices considered above. Since the absolute value of defect formation energy depends considerably on growth conditions, we evaluated the formation energies in SLS with respect to their value in the corresponding bulk or alloy. The calculated defect formation energies, together with defect energy level results, allow us to identify a few promising SLS designs for high-performing photodetectors.

Collection, use, and protection of population-based birth defects surveillance data in the united states.

PubMed

Mai, Cara T; Law, David J; Mason, Craig A; McDowell, Bradley D; Meyer, Robert E; Musa, Debra

2007-12-01

Birth defects surveillance systems collect population-based birth defects data from multiple sources to track trends in prevalence, identify risk factors, refer affected families to services, and evaluate prevention efforts. Strong state and federal public health and legal mandates are in place to govern the collection and use of these data. Despite the prima facie appeal of "opt-in" and similar strategies to those who view data collection as a threat to privacy, the use of these strategies in lieu of population-based surveillance can severely limit the ability of public health agencies to accurately access the health status of a group within a defined geographical area. With the need for population-based data central to their mission, birth defects programs around the country take their data stewardship role seriously, recognizing both moral and legal obligations to protect the data by employing numerous safeguards. Birth defects surveillance systems are shaped by the needs of the community they are designed to serve, with the goal of preventing birth defects or alleviating the burdens associated with them. (c) 2007 Wiley-Liss, Inc.

Elementary defects in graphane

NASA Astrophysics Data System (ADS)

Podlivaev, A. I.; Openov, L. A.

2017-07-01

The main zero-dimensional defects in graphane, a completely hydrogenated single-layer graphene, having the chair-type conformation have been numerically simulated. The hydrogen and carbon-hydrogen vacancies, Stone-Wales defect, and "transmutation defect" resulting from the simultaneous hoppings of two hydrogen atoms between the neighboring carbon atoms have been considered. The energies of formations of these defects have been calculated and their effect on the electronic structure, phonon spectra, and Young modulus has been studied.

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. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

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…

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.

Challenges in the reconstruction of bilateral maxillectomy defects.

PubMed

Joseph, Shawn T; Thankappan, Krishnakumar; Buggaveeti, Rahul; Sharma, Mohit; Mathew, Jimmy; Iyer, Subramania

2015-02-01

Bilateral maxillectomy defects, if not adequately reconstructed, can result in grave esthetic and functional problems. The purpose of this study was to investigate the outcome of reconstruction of such defects. This is a retrospective case series. The defects were analyzed for their components and the flaps used for reconstruction. Outcomes for flap loss and functional indices, including oral diet, speech, and dental rehabilitation, also were evaluated. Ten consecutive patients who underwent bilateral maxillectomy reconstruction received 14 flaps. Six patients had malignancies of the maxilla, and 4 patients had nonmalignant indications. Ten bony free flaps were used. Four soft tissue flaps were used. The fibula free flap was the most common flap used. Three patients had total flap loss. Seven patients were alive and available for functional evaluation. Of these, 4 were taking an oral diet with altered consistency and 2 were on a regular diet. Speech was intelligible in all patients. Only 2 patients opted for dental rehabilitation with removable dentures. Reconstruction after bilateral maxillectomy is essential to prevent esthetic and functional problems. Bony reconstruction is ideal. The fibula bone free flap is commonly used. The complexity of the defect makes reconstruction difficult and the initial success rate of free flaps is low. Secondary reconstructions after the initial flap failures were successful. A satisfactory functional outcome can be achieved. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Tuning of defects in ZnO nanorod arrays used in bulk heterojunction solar cells

PubMed Central

2012-01-01

With particular focus on bulk heterojunction solar cells incorporating ZnO nanorods, we study how different annealing environments (air or Zn environment) and temperatures impact on the photoluminescence response. Our work gives new insight into the complex defect landscape in ZnO, and it also shows how the different defect types can be manipulated. We have determined the emission wavelengths for the two main defects which make up the visible band, the oxygen vacancy emission wavelength at approximately 530 nm and the zinc vacancy emission wavelength at approximately 630 nm. The precise nature of the defect landscape in the bulk of the nanorods is found to be unimportant to photovoltaic cell performance although the surface structure is more critical. Annealing of the nanorods is optimum at 300°C as this is a sufficiently high temperature to decompose Zn(OH)2 formed at the surface of the nanorods during electrodeposition and sufficiently low to prevent ITO degradation. PMID:23186280

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.

Positron-annihilation 2D-ACAR studies of disordered and defected alloys

NASA Astrophysics Data System (ADS)

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.

Theoretical Study of Defect Signatures in III-V and II-VI Semiconductors

DTIC Science & Technology

2006-03-01

collaboration with experimentalists at Linköpin University (Sweden), we identified the recently observed EPR signals in diluted GaPN to be Gallium ...the results from USPP calculations to all electron calculations. o Study NO-Zni complexes and other point defects in ZnO using USPP calculations...parameters for point defects in semiconductors. o Results on stability of NO-Zni complexes in ZnO and preliminary results on their electronic

Characterisation and modelling of defect formation in direct-chill cast AZ80 alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mackie, D.; Robson, J.D.; Withers, P.J.

2015-06-15

Wrought magnesium alloys for demanding structural applications require high quality defect free cast feedstock. The aim of this study was to first identify and characterise typical defects in direct chill cast magnesium–aluminium–zinc (AZ) alloy billet and then use modelling to understand the origins of these defects so they can be prevented. Defects were first located using ultrasonic inspection and were then characterised using X-ray computed tomography (XCT) and serial sectioning, establishing the presence of oxide films and intermetallic particles Al{sub 8}Mn{sub 5} in all defects. A model was developed to predict the flow patterns and growth kinetics of the intermetallicmore » phases during casting, which influence the formation of defects. Simulation of the growth of the intermetallic particles demonstrated that precipitation from the liquid occurs in the mould. The combination of the entrained oxide films and intermetallic particles recirculates in the liquid metal and continues to grow, until large enough to settle, which is predicted to occur at the centre of the mould where the flow is the slowest. Based on these predictions, strategies to reduce the susceptibility to defect formation are suggested. - Highlights: • Casting defects in magnesium direct chill casting have been imaged and characterised in 3-dimensions. • The occurrences of co-located clusters of particles and oxide films have been characterised and explained. • A coupled model has been developed to help interpret the observed trend for defects located towards the centre of billets.« less

Tight-binding molecular-dynamics study of point defects in GaAs

NASA Astrophysics Data System (ADS)

Seong, Hyangsuk; Lewis, Laurent J.

1995-08-01

Tight-binding molecular-dynamics simulations at 0 K have been performed in order to study the effect of defects (vacancies and antisites) in different states of charge on the electronic and structural properties of GaAs. Relaxations are fully included in the model, and for each defect we calculate the local atomic structure, the volume change upon relaxing, the formation energy (including chemical potential contributions), and the ionization levels. We find Ga vacancies to relax by an amount which is independent of the state of charge, consistent with positron lifetime measurements. Our calculations also predict Ga vacancies to exhibit a negative-U effect, and to assume a triply negative charge state for most values of the electron chemical potential. The relaxation of As vacancies, on the contrary, depends sensitively on the state of charge. The model confirms the two experimentally observed ionization levels for this defect, just below the conduction-band minimum. Likewise, Ga antisites exhibit large relaxations. In fact, in the neutral state, relaxation is so large that it leads to a ``broken-bond'' configuration, in excellent accord with the first-principles calculations of Zhang and Chadi [Phys. Rev. Lett. 64, 1789 (1990)]. This system also exhibits a negative-U effect, for values of the electron chemical potential near midgap. For As antisites, we find only a weak relaxation, independent of the charge. The model predicts the neutral state of the defect to be the ground state for values of the electron chemical potential near and above midgap, which supports the view that the EL2 defect is a neutral As antisite. Upon comparing the formation energies of the various defects we finally find that, for all values of the atomic chemical potentials, antisites are most likely to occur than vacancies.

EPIDEMIOLOGY STUDY OF BIRTH DEFECTS AND DISINFECTION BYPRODUCTS (DBPS)

EPA Science Inventory

Birth defects are the leading cause of infant mortality in the US, accounting for more than 20% of all infant deaths. In addition, birth defects are the fifth leading cause of years of potential life lost and contribute substantially to childhood morbidity and long-term disabilit...

Ion beam induced defects in solids studied by optical techniques

NASA Astrophysics Data System (ADS)

Comins, J. D.; Amolo, G. O.; Derry, T. E.; Connell, S. H.; Erasmus, R. M.; Witcomb, M. J.

2009-08-01

Optical methods can provide important insights into the mechanisms and consequences of ion beam interactions with solids. This is illustrated by four distinctly different systems. X- and Y-cut LiNbO 3 crystals implanted with 8 MeV Au 3+ ions with a fluence of 1 × 10 17 ions/cm 2 result in gold nanoparticle formation during high temperature annealing. Optical extinction curves simulated by the Mie theory provide the average nanoparticle sizes. TEM studies are in reasonable agreement and confirm a near-spherical nanoparticle shape but with surface facets. Large temperature differences in the nanoparticle creation in the X- and Y-cut crystals are explained by recrystallisation of the initially amorphised regions so as to recreate the prior crystal structure and to result in anisotropic diffusion of the implanted gold. Defect formation in alkali halides using ion beam irradiation has provided new information. Radiation-hard CsI crystals bombarded with 1 MeV protons at 300 K successfully produce F-type centres and V-centres having the I3- structure as identified by optical absorption and Raman studies. The results are discussed in relation to the formation of interstitial iodine aggregates of various types in alkali iodides. Depth profiling of I3- and I5- aggregates created in RbI bombarded with 13.6 MeV/A argon ions at 300 K is discussed. The recrystallisation of an amorphous silicon layer created in crystalline silicon bombarded with 100 keV carbon ions with a fluence of 5 × 10 17 ions/cm 2 during subsequent high temperature annealing is studied by Raman and Brillouin light scattering. Irradiation of tin-doped indium oxide (ITO) films with 1 MeV protons with fluences from 1 × 10 15 to 250 × 10 15 ions/cm -2 induces visible darkening over a broad spectral region that shows three stages of development. This is attributed to the formation of defect clusters by a model of defect growth and also high fluence optical absorption studies. X-ray diffraction studies show

Birth Defects

MedlinePlus

... both. Some birth defects like cleft lip or neural tube defects are structural problems that can be ... during pregnancy is a key factor in causing neural tube defects. For most birth defects, the cause ...

National Birth Defects Prevention Study (NBDPS)

MedlinePlus

... it was not very common for women to work in places with PAHs. PAH exposure occurred most often among women working in food preparation and serving. Pregnant women who worked in places with any PAHs were more likely to have ...

Ammonia toxicity and its prevention in inherited defects of the urea cycle.

PubMed

Walker, V

2009-09-01

The urea cycle is the final pathway for removal of surplus nitrogen from the body, and the major route in humans for detoxification of ammonia. The full complement of enzymes is expressed only in liver. Inherited deficiencies of urea cycle enzymes lead to hyperammonaemia, which causes brain damage. Severe defects present with hyperammonaemic crises in neonates. Equally devastating episodes may occur in previously asymptomatic adults with mild defects, most often X-linked ornithine transcarbamylase (OTC) deficiency. Several mechanisms probably contribute to pathogenesis. Treatment aims to reduce plasma ammonia quickly, reduce production of waste nitrogen, dispose of waste nitrogen using alternative pathways to the urea cycle and replace arginine. These therapies have increased survival and probably improve the neurological outcome. Arginine, sodium benzoate, sodium phenylbutyrate and, less often, sodium phenylacetate are used. Long-term correction is achieved by liver transplantation. Gene therapy for OTC deficiency is effective in animals, and work is ongoing to improve persistence and safety.

Scanning electron microscope automatic defect classification of process induced defects

NASA Astrophysics Data System (ADS)

Wolfe, Scott; McGarvey, Steve

2017-03-01

With the integration of high speed Scanning Electron Microscope (SEM) based Automated Defect Redetection (ADR) in both high volume semiconductor manufacturing and Research and Development (R and D), the need for reliable SEM Automated Defect Classification (ADC) has grown tremendously in the past few years. In many high volume manufacturing facilities and R and D operations, defect inspection is performed on EBeam (EB), Bright Field (BF) or Dark Field (DF) defect inspection equipment. A comma separated value (CSV) file is created by both the patterned and non-patterned defect inspection tools. The defect inspection result file contains a list of the inspection anomalies detected during the inspection tools' examination of each structure, or the examination of an entire wafers surface for non-patterned applications. This file is imported into the Defect Review Scanning Electron Microscope (DRSEM). Following the defect inspection result file import, the DRSEM automatically moves the wafer to each defect coordinate and performs ADR. During ADR the DRSEM operates in a reference mode, capturing a SEM image at the exact position of the anomalies coordinates and capturing a SEM image of a reference location in the center of the wafer. A Defect reference image is created based on the Reference image minus the Defect image. The exact coordinates of the defect is calculated based on the calculated defect position and the anomalies stage coordinate calculated when the high magnification SEM defect image is captured. The captured SEM image is processed through either DRSEM ADC binning, exporting to a Yield Analysis System (YAS), or a combination of both. Process Engineers, Yield Analysis Engineers or Failure Analysis Engineers will manually review the captured images to insure that either the YAS defect binning is accurately classifying the defects or that the DRSEM defect binning is accurately classifying the defects. This paper is an exploration of the feasibility of the

Investigation of membranous ventricular septal defect complicated with tricuspid regurgitation in ventricular septal defect occlusion

PubMed Central

LIU, SHU-PING; LI, LI; YAO, KE-CHUN; WANG, NA; WANG, JIAN-CHANG

2013-01-01

This study aimed to explore the mechanism of membranous ventricular septal defect complicated with tricuspid regurgitation and the significance of ventricular septal defect occlusion by echocardiography. A total of 43 patients with membranous ventricular septal defect complicated with tricuspid regurgitation were observed by echocardiography and the changes in length, area and volume of tricuspid regurgitation prior to and following ventricular septal defect occlusion were measured. There were four different mechanisms of membranous ventricular septal defect complicated with tricuspid regurgitation. The various indices of tricuspid regurgitation volume were significantly reduced following occlusion. Ventricular septal defect occlusion significantly reduces tricuspid regurgitation volume complicated with membranous ventricular septal defect and echocardiography is an ideal method to detect these changes. PMID:23404058

Atomic defects in monolayer WSe2 tunneling FETs studied by systematic ab initio calculations

NASA Astrophysics Data System (ADS)

Wu, Jixuan; Fan, Zhiqiang; Chen, Jiezhi; Jiang, Xiangwei

2018-05-01

Atomic defects in monolayer WSe2 tunneling FETs (TFETs) are studied through systematic ab initio calculations aiming at performance predictions and enhancements. The effects of various defect positions and different passivation atoms are characterized in WSe2 TFETs by rigorous ab initio quantum transport simulations. It is suggested that the Se vacancy (VSe) defect located in the gate-controlled channel region tends to increase the OFF current (I off), whereas it can be well suppressed by oxygen passivation. It is demonstrated that chlorine (Cl) passivation at the source-side tunneling region can largely suppress I off, leading to an impressively improved on–off ratio (I on/I off) compared with that without any defect. However, it is also observed that randomly positioned atomic defects tend to induce significant fluctuation of the TFET output. Further discussions are made with focus on the performance-variability trade-off for robust circuit design.

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.

Implantation of a cone-shaped double-fixed patch increases abdominal space and prevents recurrence of large defects in congenital diaphragmatic hernia.

PubMed

Loff, Steffan; Wirth, Hartmut; Jester, Iwgo; Hosie, Stuart; Wollmann, Carmen; Schaible, Thomas; Ataman, Ozge; Waag, Karl-Ludwig

2005-11-01

Large defects in patients with congenital diaphragmatic hernia (CDH) are frequently closed with a polytetrafluoroethylene patch (PTFE). Intraoperative problems include lack of abdominal domain for the reduction of organs and closure of the abdominal wall. Main surgical postoperative complication is the recurrence of the hernia. We suggest a new and easy method of patch implantation, improving these problems, and report first follow-up results. In our clinic, 103 children with CDH were treated, and 87 children underwent reconstruction of the diaphragm in the 5 years between 1998 and 2002. In 52 patients, a patch implantation had to be performed. We have been optimizing our complete pediatric and surgical procedure and present a new standardized technique of preparation and implantation of a PTFE patch. The flat patch is folded to a 90 degrees cone. The cone is fixed in its form with few single stitches. It is implanted with an overlapping border of 1 cm circumferentially. The border is separately fixed with absorbable single stitches to keep from rolling up. The rough side of the patch points toward the rim of the diaphragm to enable ingrowth of the connective tissue. In a 1-year follow-up study, the recurrences in the 3 following groups of PTFE patches were studied: conventional implantation (simple patch without overlapping border), patch with separately fixed overlapping border, and cone-shaped patch with overlapping separately fixed border. Thirty-three patients were included in the study. After conventional PTFE-patch implantation, 6 (46%) of 13 patients developed reherniation. After PTFE-patch implantation with separately fixed overlapping border, 1 (11%) of 9 patients had a recurrent hernia. In the group with the PTFE-cone implantation, 1 (9%) of 11 patients developed a recurrence. Meanwhile, another 20 CDH patients received implantation of a cone-shaped patch, and no further recurrence occurred up to now. With the additional space (20 mL) provided by the

Entanglement entropy in integrable field theories with line defects II. Non-topological defect

NASA Astrophysics Data System (ADS)

Jiang, Yunfeng

2017-08-01

This is the second part of two papers where we study the effect of integrable line defects on bipartite entanglement entropy in integrable field theories. In this paper, we consider non-topological line defects in Ising field theory. We derive an infinite series expression for the entanglement entropy and show that both the UV and IR limits of the bulk entanglement entropy are modified by the line defect. In the UV limit, we give an infinite series expression for the coefficient in front of the logarithmic divergence and the exact defect g-function. By tuning the defect to be purely transmissive and reflective, we recover correctly the entanglement entropy of the bulk and with integrable boundary respectively.

Ceramic Defects in Metal-Ceramic Fixed Dental Prostheses Made from Co-Cr and Au-Pt Alloys: A Retrospective Study.

PubMed

Mikeli, Aikaterini; Boening, Klaus W; Lißke, Benjamin

2015-01-01

Ceramic defects in porcelain-fused-to-metal (PFM) restorations may depend on framework alloy type. This study assessed ceramic defects on cobalt-chromium- (Co-Cr-) and gold-platinum- (Au-Pt-) based PFM restorations. In this study, 147 Co-Cr-based and 168 Au-Pt-based PFM restorations inserted between 1998 and 2010 (139 patients) were examined for ceramic defects. Detected defects were assigned to three groups according to clinical defect relevance. Ceramic defect rates (Co-Cr-based: 12.9%; Au-Pt-based: 7.2%) revealed no significant difference but a strong statistical trend (U test, P = .082). Most defects were of little clinical relevance. Co-Cr PFM restorations may be at higher risk for ceramic defects compared to Au-Pt-based restorations.

Oxygen-related 1-platinum defects in silicon: An electron paramagnetic resonance study

NASA Astrophysics Data System (ADS)

Juda, U.; Scheerer, O.; Höhne, M.; Riemann, H.; Schilling, H.-J.; Donecker, J.; Gerhardt, A.

1996-09-01

A monoclinic 1-platinum defect recently detected was investigated more thoroughly by electron paramagnetic resonance (EPR). The defect is one of the dominating defects in platinum doped silicon. With a perfect reproducibility it is observed in samples prepared from n-type silicon as well as from p-type silicon, in float zone (FZ) silicon as well as in Czochralski (Cz) silicon. Its concentration varies with the conditions of preparation and nearly reaches that of isolated substitutional platinum in Cz silicon annealed for 2 h at 540 °C after quenching from the temperature of platinum diffusion. Because of its concentration which in Cz-Si exceeds that in FZ-Si the defect is assumed to be oxygen-related though a hyperfine structure with 17O could not be resolved. The defect causes a level close to the valence band. This is concluded from variations of the Fermi level and from a discussion of the spin Hamiltonian parameters. In photo-EPR experiments the defect is coupled to recently detected acceptorlike self-interstitial related defects (SIRDs); their level position turns out to be near-midgap. These defects belong to the lifetime limiting defects in Pt-doped Si.

Birth defects among a cohort of infants born to HIV-infected women on antiretroviral medication

PubMed Central

Watts, D. Heather; Huang, Sharon; Culnane, Mary; Kaiser, Kathleen A.; Scheuerle, Angela; Mofenson, Lynne; Stanley, Kenneth; Newell, Marie-Louise; Mandelbrot, Laurent; Delfraissy, Jean-Francois; Cunningham, Coleen K.

2011-01-01

Objective To determine rate of and risk factors for birth defects in infants born to HIV-infected women receiving nucleoside and protease inhibitor antiretroviral (ARV) therapy. Methods Birth defects were evaluated among infants on the Pediatric AIDS Clinical Trials Group 316 trial that studied addition of peripartum nevirapine to established ARV regimen for prevention of mother-to-child transmission. Maternal therapy was categorized by trimester of earliest exposure. Birth defects were coded using conventions of the Antiretroviral Pregnancy Registry. Results Birth defects were detected in 60/1414 (4.2%; 95% CI 3.3–5.4%) infants including 30/636 (4.7%; 95% CI 3.2–6.7%) with first trimester ARV exposure and 30/778 (3.9%; 95% CI 2.6–5.5%) with exposure only after the first trimester (P=0.51). Rates of classes of defects were similar between first trimester compared to later exposure groups except heart defects which occurred in 16 (2.5%; 95% CI 1.4–4.1%) with first trimester ARV exposure and in six (0.8%; 95% CI 0.3–1.7%) infants with later exposure (P=0.02). Exposure to ARV was not associated with specific types of heart defects. Two cases of cardiomyopathy were noted. Conclusion ARV use in early pregnancy was not associated with an increased risk of birth defects overall. The possible association of ARV exposure with heart defects requires further surveillance. PMID:21142844

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.

Anal sphincter defects and fecal incontinence 15-24 years after first delivery: a cross-sectional study.

PubMed

Guzmán Rojas, R A; Salvesen, K Å; Volløyhaug, I

2018-05-01

To establish the prevalence of external (EAS) and internal (IAS) anal sphincter defects present 15-24 years after childbirth according to mode of delivery, and their association with development of fecal incontinence (FI). The study additionally aimed to compare the proportion of women with obstetric anal sphincter injuries (OASIS) reported at delivery with the proportion of women with sphincter defect detected on ultrasound 15-24 years later. This was a cross-sectional study including 563 women who delivered their first child between 1990 and 1997. Women responded to a validated questionnaire (Pelvic Floor Distress Inventory) in 2013-2014, from which the proportion of women with FI was recorded. Information about OASIS was obtained from the National Birth Registry. Study participants underwent four-dimensional transperineal ultrasound examination. Defect of EAS or IAS of ≥ 30° in at least four of six slices on tomographic ultrasound was considered a significant defect and was recorded. Four study groups were defined based on mode of delivery of the first child. Women who had delivered only by Cesarean section (CS) constituted the CS group. Women in the normal vaginal delivery (NVD) group had NVD of their first child and subsequent deliveries could be NVD or CS. The forceps delivery (FD) group included women who had FD, NVD or CS after FD of their first born. The vacuum delivery (VD) group included women who had VD, NVD or CS after VD of their first born. Multiple logistic regression was used to calculate adjusted odds ratios (aORs) for comparison of prevalence of an EAS defect following different modes of delivery and to test its association with FI. Fisher's exact test was used to calculate crude odds ratios (ORs) for IAS defects. Defects of EAS and IAS were found after NVD (n = 201) in 10% and 1% of cases, respectively, after FD (n = 144) in 32% and 7% of cases and after VD (n = 120) in 15% and 4% of cases. No defects were found after CS (n�

Air pollution and limb defects: a matched-pairs case-control study in Taiwan.

PubMed

Lin, Yu-Ting; Lee, Yungling Leo; Jung, Chau-Ren; Jaakkola, Jouni J K; Hwang, Bing-Fang

2014-07-01

Air pollution influences the development of limb defects in animals. There is little epidemiologic evidence on the effect of prenatal air pollution exposure on the risk of limb defects. To assess the relations between exposure to ambient air pollutants and the risk of limb defects. We conducted a matched-pairs case-control study in Taiwan from 2001 through 2007. The case group consisted of 1687 limb defects and the control group was density-sampling matched one to ten based on the month and year of conception from 1510,064 live singleton newborns in 2001-2007. Adjusted conditional logistic regression models were used to estimate odds ratios per 10 ppb change for O3, NO2, 1 ppb change for SO2, 10 µg/m(3) change for PM10, and 100 ppb change for CO during the first trimester and first three gestational months. Of the specific limb defects, reduction deformities of limbs (adjusted OR=1.024, 95% CI: 1.000, 1.048) was associated with a 1 ppb increase in SO2 during weeks of 9-12 of gestation as well as the first trimester. Reduction deformities of limbs was also associated with a 10 ppb increase in O3 during weeks of 1-4 of gestation (adjusted OR=1.391, 95% CI: 1.064, 1.818) among preterm births. The present study provides evidence that exposure to outdoor air SO2 during the first trimester of pregnancy may increase the risk of limb defects. Exposure to O3 was associated with reduction deformities of limbs among preterm births. Similar levels of SO2 and O3 are encountered globally by large numbers of pregnant women. Copyright © 2014 Elsevier Inc. All rights reserved.

Anatomy of the ventricular septal defect in outflow tract defects: similarities and differences.

PubMed

Mostefa-Kara, Meriem; Bonnet, Damien; Belli, Emre; Fadel, Elie; Houyel, Lucile

2015-03-01

The study objective was to analyze the anatomy of the ventricular septal defect found in various phenotypes of outflow tract defects. We reviewed 277 heart specimens with isolated outlet ventricular septal defect without subpulmonary stenosis (isolated outlet ventricular septal defect, 19); tetralogy of Fallot (71); tetralogy of Fallot with pulmonary atresia (51); common arterial trunk (54); double outlet right ventricle (65) with subaortic, doubly committed, or subpulmonary ventricular septal defect; and interrupted aortic arch type B (17). Special attention was paid to the rims of the ventricular septal defect viewed from the right ventricular side and the relationships between the tricuspid and aortic valves. The ventricular septal defect was always located in the outlet of the right ventricle, between the 2 limbs of the septal band. There was a fibrous continuity between the tricuspid and aortic valves in 74% of specimens with isolated outlet ventricular septal defect, 66% of specimens with tetralogy of Fallot, 39% of specimens with tetralogy of Fallot with pulmonary atresia, 4.6% of specimens with double outlet right ventricle, 1.8% of specimens with common arterial trunk, and zero of specimens with interrupted aortic arch type B (P < .005). When present, this continuity always involved the anterior tricuspid leaflet. The ventricular septal defect in outflow tract defects is always an outlet ventricular septal defect, cradled between the 2 limbs of the septal band. However, there are some differences regarding the posteroinferior and superior rims of the ventricular septal defect. These differences suggest an anatomic continuum from the isolated outlet ventricular septal defect to the interrupted aortic arch type B rather than distinct physiologic phenotypes, related to various degrees of abnormal rotation of the outflow tract during heart development: minimal in isolated outlet ventricular septal defect; incomplete in tetralogy of Fallot, tetralogy of Fallot

Effects of defects in composite structures

NASA Technical Reports Server (NTRS)

Sendeckyj, G. P.

1983-01-01

The effect of defects in composite structures is addressed. Defects in laminates such as wrinkles, foreign particles, scratches and breaks are discussed. Effects of plygap plywaviness and machining defects are also studied.

Quantitative Experimental Study of Defects Induced by Process Parameters in the High-Pressure Die Cast Process

NASA Astrophysics Data System (ADS)

Sharifi, P.; Jamali, J.; Sadayappan, K.; Wood, J. T.

2018-05-01

A quantitative experimental study of the effects of process parameters on the formation of defects during solidification of high-pressure die cast magnesium alloy components is presented. The parameters studied are slow-stage velocity, fast-stage velocity, intensification pressure, and die temperature. The amount of various defects are quantitatively characterized. Multiple runs of the commercial casting simulation package, ProCAST™, are used to model the mold-filling and solidification events. Several locations in the component including knit lines, last-to-fill region, and last-to-solidify region are identified as the critical regions that have a high concentration of defects. The area fractions of total porosity, shrinkage porosity, gas porosity, and externally solidified grains are separately measured. This study shows that the process parameters, fluid flow and local solidification conditions, play major roles in the formation of defects during HPDC process.

Study on on-machine defects measuring system on high power laser optical elements

NASA Astrophysics Data System (ADS)

Luo, Chi; Shi, Feng; Lin, Zhifan; Zhang, Tong; Wang, Guilin

2017-10-01

The influence of surface defects on high power laser optical elements will cause some harm to the performances of imaging system, including the energy consumption and the damage of film layer. To further increase surface defects on high power laser optical element, on-machine defects measuring system was investigated. Firstly, the selection and design are completed by the working condition analysis of the on-machine defects detection system. By designing on processing algorithms to realize the classification recognition and evaluation of surface defects. The calibration experiment of the scratch was done by using the self-made standard alignment plate. Finally, the detection and evaluation of surface defects of large diameter semi-cylindrical silicon mirror are realized. The calibration results show that the size deviation is less than 4% that meet the precision requirement of the detection of the defects. Through the detection of images the on-machine defects detection system can realize the accurate identification of surface defects.

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.

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.

Holographic Chern-Simons defects

DOE PAGES

Fujita, Mitsutoshi; Melby-Thompson, Charles M.; Meyer, René; ...

2016-06-28

Here, we study SU(N ) Yang-Mills-Chern-Simons theory in the presence of defects that shift the Chern-Simons level from a holographic point of view by embedding the system in string theory. The model is a D3-D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7 branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of themore » defects as well as the temperature are varied. We also discuss some implications for the Fractional Quantum Hall Effect and for 2-dimensional QCD.« less

Unclosed fascial defect: is it the risk to develop port-site hernia after laparoscopic cholecystectomy?

PubMed

Tangjaroen, Somard; Watanapa, Prasit

2014-02-01

Port-site hernia (PSH) is one of the complications after laparoscopic cholecystectomy (LC). Closure of the fascial defect has been mentioned to prevent such complication. However, the results are still controversial. The present study was done to clarify whether unclosed fascial defect was actually the risk factor for the development of PSH MATERIAL AND METHOD: Two hundred ninety four patients underwent LC by a single surgeon at Kalasin Hospital between 2007 and 2010. The procedure was done by using a four-port technique without closure of any fascial defects. The male:female ratio was 85:209, and the mean body mass index was 24.38 +/- 3.33 (SD). The mean operative time was 18.71 +/- 3.76 minutes and there was no postoperative wound infection. Patients were regularly followed-up and underwent both supine and upright physical examination. The mean duration of follow-up period was 4.94 +/- 1.31 years with the shortest follow-up period of two years. None of the patients in the present study developed PSH in any port sites during the follow-up period. Unclosed fascial defect may not have the significant risk factor of developing PSH after LC.

Ion beam collimating grid to reduce added defects

DOEpatents

Lindquist, Walter B.; Kearney, Patrick A.

2003-01-01

A collimating grid for an ion source located after the exit grid. The collimating grid collimates the ion beamlets and disallows beam spread and limits the beam divergence during transients and steady state operation. The additional exit or collimating grid prevents beam divergence during turn-on and turn-off and prevents ions from hitting the periphery of the target where there is re-deposited material or from missing the target and hitting the wall of the vessel where there is deposited material, thereby preventing defects from being deposited on a substrate to be coated. Thus, the addition of a collimating grid to an ion source ensures that the ion beam will hit and be confined to a specific target area.

Quasiparticle and hybrid density functional methods in defect studies: An application to the nitrogen vacancy in GaN

NASA Astrophysics Data System (ADS)

Lewis, D. K.; Matsubara, M.; Bellotti, E.; Sharifzadeh, S.

2017-12-01

Defects in semiconductors can play a vital role in the performance of electronic devices, with native defects often dominating the electronic properties of the semiconductor. Understanding the relationship between structural defects and electronic function will be central to the design of new high-performance materials. In particular, it is necessary to quantitatively understand the energy and lifetime of electronic states associated with the defect. Here, we apply first-principles density functional theory (DFT) and many-body perturbation theory within the GW approximation to understand the nature and energy of the defect states associated with a charged nitrogen vacancy on the electronic properties of gallium nitride (GaN), as a model of a well-studied and important wide gap semiconductor grown with defects. We systematically investigate the sources of error associated with the GW approximation and the role of the underlying atomic structure on the predicted defect state energies. Additionally, analysis of the computed electronic density of states (DOS) reveals that there is one occupied defect state 0.2 eV below the valence band maximum and three unoccupied defect states at energy of 0.2-0.4 eV above the conduction band minimum, suggesting that this defect in the +1 charge state will not behave as a carrier trap. Furthermore, we compare the character and energy of the defect state obtained from GW and DFT using the HSE approximate density functional and find excellent agreement. This systematic study provides a more complete understanding of how to obtain quantitative defect energy states in bulk semiconductors.

Defect studies of nanocrystalline zirconia powders and sintered ceramics

NASA Astrophysics Data System (ADS)

Čížek, Jakub; Melikhova, Oksana; Procházka, Ivan; Kuriplach, Jan; Kužel, Radomír; Brauer, Gerhard; Anwand, Wolfgang; Konstantinova, Tatyana E.; Danilenko, Igor A.

2010-01-01

The main objective of the present paper is to communicate a study of defects behavior in zirconia-based nanomaterials—pressure-compacted yttria-stabilized zirconia (YSZ) nanopowders with different contents of Y2O3 and ceramics obtained by sintering the YZS nanopowders. In addition, YZS single crystals were also investigated. Positron annihilation techniques including positron lifetime and coincidence Doppler broadening with a conventional positron source and Doppler broadening experiments on a monoenergetic positron beam were involved in this study as the principal tools. These techniques were supplemented with transmission electron microscopy and x-ray diffraction observations. In order to get better support of the experimental data interpretation, the state-of-art theoretical calculations of positron parameters were performed for the perfect ZrO2 lattice and selected defect configurations in the YSZ. Theoretical calculations have indicated that neither the oxygen vacancies nor their neutral complexes with substitutional yttrium atoms are capable of positron trapping. On the other hand, the zirconium vacancies are deep positron traps and obviously are responsible for the saturated positron trapping observed in the YSZ single crystals. In the compacted YSZ nanopowders, a majority of positrons is trapped either in the vacancylike defects situated in the negative space-charge layers along grain boundaries (τ1≈185ps) or in vacancy clusters at intersections of grain boundaries (τ2≈370ps) . The intensity ratio I2/I1 was found to be correlated with the mean grain size d as I2/I1˜d-2 . A small fraction of positrons (≈10%) form positronium in large pores (τ3≈2ns,τ4≈30ns) . A significant grain growth during sintering of the YSZ nanopowders above 1000°C was observed.

Blood flow patterns underlie developmental heart defects

PubMed Central

Midgett, Madeline; Thornburg, Kent

2017-01-01

Although cardiac malformations at birth are typically associated with genetic anomalies, blood flow dynamics also play a crucial role in heart formation. However, the relationship between blood flow patterns in the early embryo and later cardiovascular malformation has not been determined. We used the chicken embryo model to quantify the extent to which anomalous blood flow patterns predict cardiac defects that resemble those in humans and found that restricting either the inflow to the heart or the outflow led to reproducible abnormalities with a dose-response type relationship between blood flow stimuli and the expression of cardiac phenotypes. Constricting the outflow tract by 10–35% led predominantly to ventricular septal defects, whereas constricting by 35–60% most often led to double outlet right ventricle. Ligation of the vitelline vein caused mostly pharyngeal arch artery malformations. We show that both cardiac inflow reduction and graded outflow constriction strongly influence the development of specific and persistent abnormal cardiac structure and function. Moreover, the hemodynamic-associated cardiac defects recapitulate those caused by genetic disorders. Thus our data demonstrate the importance of investigating embryonic blood flow conditions to understand the root causes of congenital heart disease as a prerequisite to future prevention and treatment. NEW & NOTEWORTHY Congenital heart defects result from genetic anomalies, teratogen exposure, and altered blood flow during embryonic development. We show here a novel “dose-response” type relationship between the level of blood flow alteration and manifestation of specific cardiac phenotypes. We speculate that abnormal blood flow may frequently underlie congenital heart defects. PMID:28062416

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.

Defect Detection and Segmentation Framework for Remote Field Eddy Current Sensor Data

PubMed Central

2017-01-01

Remote-Field Eddy-Current (RFEC) technology is often used as a Non-Destructive Evaluation (NDE) method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth and shape. For large sections of pipelines, this can be extremely time-consuming if performed manually. Automated approaches are therefore well motivated. In this article, we propose an automated framework to locate and segment defects in individual pipe segments, starting from raw RFEC measurements taken over large pipelines. The framework relies on a novel feature to robustly detect these defects and a segmentation algorithm applied to the deconvolved RFEC signal. The framework is evaluated using both simulated and real datasets, demonstrating its ability to efficiently segment the shape of corrosion defects. PMID:28984823

Defect Detection and Segmentation Framework for Remote Field Eddy Current Sensor Data.

PubMed

Falque, Raphael; Vidal-Calleja, Teresa; Miro, Jaime Valls

2017-10-06

Remote-Field Eddy-Current (RFEC) technology is often used as a Non-Destructive Evaluation (NDE) method to prevent water pipe failures. By analyzing the RFEC data, it is possible to quantify the corrosion present in pipes. Quantifying the corrosion involves detecting defects and extracting their depth and shape. For large sections of pipelines, this can be extremely time-consuming if performed manually. Automated approaches are therefore well motivated. In this article, we propose an automated framework to locate and segment defects in individual pipe segments, starting from raw RFEC measurements taken over large pipelines. The framework relies on a novel feature to robustly detect these defects and a segmentation algorithm applied to the deconvolved RFEC signal. The framework is evaluated using both simulated and real datasets, demonstrating its ability to efficiently segment the shape of corrosion defects.

Infrared studies of defects formed during postirradiation anneals of Czochralski silicon

NASA Astrophysics Data System (ADS)

Londos, C. A.; Sarlis, N. V.; Fytros, L. G.

1998-10-01

This article reports on defect studies of neutron-irradiated Czochralski-grown silicon (Cz-Si) material by means of infrared spectroscopy. In particular, the investigation was focused on the evolution of the 828 cm-1 well-known band of A-center, due to isochronal anneals from room temperature (RT) up to ≈700 °C. The strength of the VO band begins to increase above ≈200 gradually up to 300 °C (stage I); then, it begins to decrease up to ≈400 °C (stage II), where upon it stabilizes up to ≈550 °C (stage III). Upon re-irradiation under exactly the same conditions and repeating the annealing process, the increase of the VO signal in stage I disappears. The phenomenon is ascribed to the existence of defect aggregates labeled as Xi centers which are correlated with (impurity-defect) clusters that compete with Oi in capturing vacancies. The presence of Xi centers is related to the thermal annealings performed. Comparison of the evolution of VO (828 cm-1) and VO2 (887 cm-1) bands between irradiated and re-irradiated materials, during stage II, is made and the results are discussed in the framework of established reaction patterns. The stabilization of the amplitude of the 828 cm-1 line in stage III is examined. The prevailing aspect is that a portion of A-centers in neutron-irradiated Si acquires larger thermal stability by relaxing in the vicinity of larger defects.

Public Health Practice of Population-Based Birth Defects Surveillance Programs in the United States.

PubMed

Mai, Cara T; Kirby, Russell S; Correa, Adolfo; Rosenberg, Deborah; Petros, Michael; Fagen, Michael C

2016-01-01

Birth defects remain a leading cause of infant mortality in the United States and contribute substantially to health care costs and lifelong disabilities. State population-based surveillance systems have been established to monitor birth defects, yet no recent systematic examination of their efforts in the United States has been conducted. To understand the current population-based birth defects surveillance practices in the United States. The National Birth Defects Prevention Network conducted a survey of US population-based birth defects activities that included questions about operational status, case ascertainment methodology, program infrastructure, data collection and utilization, as well as priorities and challenges for surveillance programs. Birth defects contacts in the United States, including District of Columbia and Puerto Rico, received the survey via e-mail; follow-up reminders via e-mails and telephone were used to ensure a 100% response rate. Forty-three states perform population-based surveillance for birth defects, covering approximately 80% of the live births in the United States. Seventeen primarily use an active case-finding approach and 26 use a passive case-finding approach. These programs all monitor major structural malformations; however, passive case-finding programs more often monitor a broader list of conditions, including developmental conditions and newborn screening conditions. Active case-finding programs more often use clinical reviewers, cover broader pregnancy outcomes, and collect more extensive information, such as family history. More than half of the programs (24 of 43) reported an ability to conduct follow-up studies of children with birth defects. The breadth and depth of information collected at a population level by birth defects surveillance programs in the United States serve as an important data source to guide public health action. Collaborative efforts at the state and national levels can help harmonize data

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.

Molecular Dynamics Study of High Symmetry Planar Defect Evolution during Growth of CdTe/CdS Films

DOE PAGES

Chavez, Jose Juan; Zhou, Xiao W.; Almeida, Sergio F.; ...

2017-12-15

The growth dynamics and evolution of intrinsic stacking faults, lamellar, and double positioning twin grain boundaries were explored using molecular dynamics simulations during the growth of CdTe homoepitaxy and CdTe/CdS heteroepitaxy. Initial substrate structures were created containing either stacking fault or one type of twin grain boundary, and films were subsequently deposited to study the evolution of the underlying defect. Results show that during homoepitaxy the film growth was epitaxial and the substrate’s defects propagated into the epilayer, except for the stacking fault case where the defect disappeared after the film thickness increased. In contrast, films grown on heteroepitaxy conditionsmore » formed misfit dislocations and grew with a small angle tilt (within ~5°) of the underlying substrate’s orientation to alleviate the lattice mismatch. Grain boundary proliferation was observed in the lamellar and double positioning twin cases. Finally, our study indicates that it is possible to influence the propagation of high symmetry planar defects by selecting a suitable substrate defect configuration, thereby controlling the film defect morphology.« less

Molecular Dynamics Study of High Symmetry Planar Defect Evolution during Growth of CdTe/CdS Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chavez, Jose Juan; Zhou, Xiao W.; Almeida, Sergio F.

The growth dynamics and evolution of intrinsic stacking faults, lamellar, and double positioning twin grain boundaries were explored using molecular dynamics simulations during the growth of CdTe homoepitaxy and CdTe/CdS heteroepitaxy. Initial substrate structures were created containing either stacking fault or one type of twin grain boundary, and films were subsequently deposited to study the evolution of the underlying defect. Results show that during homoepitaxy the film growth was epitaxial and the substrate’s defects propagated into the epilayer, except for the stacking fault case where the defect disappeared after the film thickness increased. In contrast, films grown on heteroepitaxy conditionsmore » formed misfit dislocations and grew with a small angle tilt (within ~5°) of the underlying substrate’s orientation to alleviate the lattice mismatch. Grain boundary proliferation was observed in the lamellar and double positioning twin cases. Finally, our study indicates that it is possible to influence the propagation of high symmetry planar defects by selecting a suitable substrate defect configuration, thereby controlling the film defect morphology.« less

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.

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.

Maternal dietary intake of nitrates, nitrites and nitrosamines and selected birth defects in offspring: a case-control study

PubMed Central

2013-01-01

Background 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. Methods 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. Results 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). Conclusions Overall, odds of NTDs, OCs or LDs did not appear to be significantly associated with estimated dietary intake of

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.

Stable Defects in Semiconductor Nanowires.

PubMed

Sanchez, A M; Gott, J A; Fonseka, H A; Zhang, Y; Liu, H; Beanland, R

2018-05-09

Semiconductor nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. Here, we describe previously undiscovered topologically protected line defects with null Burgers vector that, unlike dislocations, are stable in nanoscale crystals. We analyze the defects present in semiconductor nanowires in regions of imperfect crystal growth, i.e., at the nanowire tip formed during consumption of the droplet in self-catalyzed vapor-liquid-solid growth and subsequent vapor-solid shell growth. We use a form of the Burgers circuit method that can be applied to multiply twinned material without difficulty. Our observations show that the nanowire microstructure is very different from bulk material, with line defects either (a) trapped by locks or other defects, (b) arranged as dipoles or groups with a zero total Burgers vector, or (c) have a zero Burgers vector. We find two new line defects with a null Burgers vector, formed from the combination of partial dislocations in twinned material. The most common defect is the three-monolayer high twin facet with a zero Burgers vector. Studies of individual nanowires using cathodoluminescence show that optical emission is quenched in defective regions, showing that they act as strong nonradiative recombination centers.

A proposed defect tracking model for classifying the inserted defect reports to enhance software quality control.

PubMed

Sultan, Torky; Khedr, Ayman E; Sayed, Mostafa

2013-01-01

NONE DECLARED Defect tracking systems play an important role in the software development organizations as they can store historical information about defects. There are many research in defect tracking models and systems to enhance their capabilities to be more specifically tracking, and were adopted with new technology. Furthermore, there are different studies in classifying bugs in a step by step method to have clear perception and applicable method in detecting such bugs. This paper shows a new proposed defect tracking model for the purpose of classifying the inserted defects reports in a step by step method for more enhancement of the software quality.

Platelet rich fibrin in jaw defects

NASA Astrophysics Data System (ADS)

Nica, Diana; Ianes, Emilia; Pricop, Marius

2016-03-01

Platelet rich fibrin (PRF) is a tissue product of autologous origin abundant in growth factors, widely used in regenerative procedures. Aim of the study: Evaluation of the regenerative effect of PRF added in the bony defects (after tooth removal or after cystectomy) Material and methods: The comparative nonrandomized study included 22 patients divided into 2 groups. The first group (the test group) included 10 patients where the bony defects were treated without any harvesting material. The second group included 12 patients where the bony defects were filled with PRF. The bony defect design was not critical, with one to two walls missing. After the surgeries, a close clinically monitoring was carried out. The selected cases were investigated using both cone beam computer tomography (CBCT) and radiographic techniques after 10 weeks postoperatively. Results: Faster bone regeneration was observed in the bony defects filled with PRF comparing with the not grafted bony defects. Conclusions: PRF added in the bony defects accelerates the bone regeneration. This simplifies the surgical procedures and decreases the economic costs.

Topological defects from the multiverse

NASA Astrophysics Data System (ADS)

Zhang, Jun; Blanco-Pillado, Jose J.; Garriga, Jaume; Vilenkin, Alexander

2015-05-01

Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to be quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.

Topological defects from the multiverse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jun; Vilenkin, Alexander; Blanco-Pillado, Jose J.

2015-05-01

Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to bemore » quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.« less

Topological defects from the multiverse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jun; Blanco-Pillado, Jose J.; IKERBASQUE, Basque Foundation for Science, 48013, Bilbao

2015-05-28

Many theories of the early universe predict the existence of a multiverse where bubbles continuously nucleate giving rise to observers in their interior. In this paper, we point out that topological defects of several dimensionalities will also be produced in de Sitter like regions of the multiverse. In particular, defects could be spontaneously nucleated in our parent vacuum. We study the evolution of these defects as they collide with and propagate inside of our bubble. We estimate the present distribution of defects in the observable part of the universe. The expected number of such nearby defects turns out to bemore » quite small, even for the highest nucleation rate. We also study collisions of strings and domain walls with our bubble in our past light cone. We obtain simulated full-sky maps of the loci of such collisions, and find their angular size distribution. Similarly to what happens in the case of bubble collisions, the prospect of detecting any collisions of our bubble with ambient defects is greatly enhanced in the case where the cosmological constant of our parent vacuum is much higher than the vacuum energy density during inflation in our bubble.« less

Operator product expansion for conformal defects

NASA Astrophysics Data System (ADS)

Fukuda, Masayuki; Kobayashi, Nozomu; Nishioka, Tatsuma

2018-01-01

We study the operator product expansion (OPE) for scalar conformal defects of any codimension in CFT. The OPE for defects is decomposed into "defect OPE blocks", the irreducible representations of the conformal group, each of which packages the contribution from a primary operator and its descendants. We use the shadow formalism to deduce an integral representation of the defect OPE blocks. They are shown to obey a set of constraint equations that can be regarded as equations of motion for a scalar field propagating on the moduli space of the defects. By employing the Radon transform between the AdS space and the moduli space, we obtain a formula of constructing an AdS scalar field from the defect OPE block for a conformal defect of any codimension in a scalar representation of the conformal group, which turns out to be the Euclidean version of the HKLL formula. We also introduce a duality between conformal defects of different codimensions and prove the equivalence between the defect OPE block for codimension-two defects and the OPE block for a pair of local operators.

Self-fitting shape memory polymer foam inducing bone regeneration: A rabbit femoral defect study.

PubMed

Xie, Ruiqi; Hu, Jinlian; Hoffmann, Oskar; Zhang, Yuanchi; Ng, Frankie; Qin, Tingwu; Guo, Xia

2018-04-01

Although tissue engineering has been attracted greatly for healing of critical-sized bone defects, great efforts for improvement are still being made in scaffold design. In particular, bone regeneration would be enhanced if a scaffold precisely matches the contour of bone defects, especially if it could be implanted into the human body conveniently and safely. In this study, polyurethane/hydroxyapatite-based shape memory polymer (SMP) foam was fabricated as a scaffold substrate to facilitate bone regeneration. The minimally invasive delivery and the self-fitting behavior of the SMP foam were systematically evaluated to demonstrate its feasibility in the treatment of bone defects in vivo. Results showed that the SMP foam could be conveniently implanted into bone defects with a compact shape. Subsequently, it self-matched the boundary of bone defects upon shape-recovery activation in vivo. Micro-computed tomography determined that bone ingrowth initiated at the periphery of the SMP foam with a constant decrease towards the inside. Successful vascularization and bone remodeling were also demonstrated by histological analysis. Thus, our results indicate that the SMP foam demonstrated great potential for bone regeneration. Copyright © 2018 Elsevier B.V. All rights reserved.

Immobile defects in ferroelastic walls: Wall nucleation at defect sites

NASA Astrophysics Data System (ADS)

He, X.; Salje, E. K. H.; Ding, X.; Sun, J.

2018-02-01

Randomly distributed, static defects are enriched in ferroelastic domain walls. The relative concentration of defects in walls, Nd, follows a power law distribution as a function of the total defect concentration C: N d ˜ C α with α = 0.4 . The enrichment Nd/C ranges from ˜50 times when C = 10 ppm to ˜3 times when C = 1000 ppm. The resulting enrichment is due to nucleation at defect sites as observed in large scale MD simulations. The dynamics of domain nucleation and switching is dependent on the defect concentration. Their energy distribution follows the power law with exponents during yield between ɛ ˜ 1.82 and 2.0 when the defect concentration increases. The power law exponent is ɛ ≈ 2.7 in the plastic regime, independent of the defect concentration.

Improving the Quality of Cast Ingot for the Production of Defect-Free Rolled and Polished Blanks of Silver-Copper Coinage Alloy

NASA Astrophysics Data System (ADS)

Chakrabarti, Debalay; Chakrabarti, Ajit Kumar; Roy, Sanat Kumar

2018-05-01

The causes of defect generation in Ag-7.5 wt% Cu coinage alloy billets and in rolled and polished blanks were evaluated in this paper. Microstructural and compositional study of the as-cast billets indicated that excessive formation of gas-porosity and shrinkage cavity was responsible for crack formation during rolling. Carbon pick-up from charcoal flux cover used during melting, formation of CuS inclusions due to high-S content and rapid work-hardening also contributed to cracking during rolling. In order to prevent the defect generation, several measures were adopted. Those measures significantly reduced the defect generation and improved the surface luster of the trial rolled strips.

Brain abscess of odontogenic origin in a man with interatrial defect.

PubMed

Milli, Bruna; Rocci, Anna; Paganelli, Enrico; Degli Antoni, Gino; Monaco, Delio; Quintavalla, Roberto

2010-12-01

A 65-year-old man with previous surgery for cyanotic congenital heart disease was admitted to our hospital with fever, headache and visual disturbances due to a right occipital brain abscess as shown through CT-scan. A comprehensive workup looking for a source of infection was negative except for an orthopantomogram showing multiple dental caries. A transesophageal echocardiogram (TEE) bubble study revealed the permanence of an atrial septal defect with a moderate right-to-left shunt. The culture of the abscess content showed flora commonly found in the oropharynx that responded to antimicrobial therapy. We hypothesize that the underlying mechanism is a significant bacterial load from dental infections that enters the arterial circulation through the interatrial defect. If a brain abscess is identified without any adjacent source of infection, then a transesophageal echocardiogram is indicated to exclude right to left shunt. If a shunt is found, then hematogenous spread of flora normally found in the oropharynx should be suspected. Surgical evacuation followed by antimicrobial therapy is warranted. Once the infection is eliminated, long term anticoagulation or anatomic closure of the interatrial defect with good oral hygiene could be valid strategies for preventing recurrence.

Ion channeling study of defects in compound crystals using Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Turos, A.; Jozwik, P.; Nowicki, L.; Sathish, N.

2014-08-01

Ion channeling is a well-established technique for determination of structural properties of crystalline materials. Defect depth profiles have been usually determined basing on the two-beam model developed by Bøgh (1968) [1]. As long as the main research interest was focused on single element crystals it was considered as sufficiently accurate. New challenge emerged with growing technological importance of compound single crystals and epitaxial heterostructures. Overlap of partial spectra due to different sublattices and formation of complicated defect structures makes the two beam method hardly applicable. The solution is provided by Monte Carlo computer simulations. Our paper reviews principal aspects of this approach and the recent developments in the McChasy simulation code. The latter made it possible to distinguish between randomly displaced atoms (RDA) and extended defects (dislocations, loops, etc.). Hence, complex defect structures can be characterized by the relative content of these two components. The next refinement of the code consists of detailed parameterization of dislocations and dislocation loops. Defect profiles for variety of compound crystals (GaN, ZnO, SrTiO3) have been measured and evaluated using the McChasy code. Damage accumulation curves for RDA and extended defects revealed non monotonous defect buildup with some characteristic steps. Transition to each stage is governed by the different driving force. As shown by the complementary high resolution XRD measurements lattice strain plays here the crucial role and can be correlated with the concentration of extended defects.

Functional defect in regulatory T cells in myasthenia gravis

PubMed Central

Thiruppathi, Muthusamy; Rowin, Julie; Jiang, Qin Li; Sheng, Jian Rong; Prabhakar, Bellur S.; Meriggioli, Matthew N.

2012-01-01

Forkhead box P3 (FOXP3)+ is a transcription factor necessary for the function of regulatory T cells (Treg cells). Treg cells maintain immune homeostasis and self-tolerance, and play an important role in the prevention of autoimmune disease. Here, we discuss the role of Treg cells in the pathogenesis of myasthenia gravis (MG) and review evidence indicating that a significant defect in Treg cell in vitro suppressive function exists in MG patients, without an alteration in circulating frequency. This functional defect is associated with a reduced expression of key functional molecules such as FOXP3 on isolated Treg cells and appears to be more pronounced in immunosuppression-naive MG patients. In vitro administration of granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced the suppressive function of Treg cells and up-regulated FOXP3 expression. These findings indicate a clinically relevant Treg cell–intrinsic defect in immune regulation in MG that may reveal a novel therapeutic target. PMID:23252899

Proteomic approach to characterize biochemistry of meat quality defects.

PubMed

Schilling, M W; Suman, S P; Zhang, X; Nair, M N; Desai, M A; Cai, K; Ciaramella, M A; Allen, P J

2017-10-01

Proteomics can be used to characterize quality defects including pale, soft, and exudative (PSE) meat (pork and poultry), woody broiler breast meat, reddish catfish fillets, meat toughness, and beef myoglobin oxidation. PSE broiler meat was characterized by 15 proteins that differed in abundance in comparison to normal broiler breast meat, and eight proteins were differentially expressed in woody breast meat in comparison to normal breast meat. Hemoglobin was the only protein that was differentially expressed between red and normal catfish fillets. However, inducing low oxygen and/or heat stress conditions to catfish fillets did not lead to the production of red fillets. Proteomic data provided information pertaining to the protein differences that exist in meat quality defects. However, these data need to be evaluated in conjunction with information pertaining to genetics, nutrition, environment of the live animal, muscle to meat conversion, meat quality analyses and sensory attributes to understand causality, protein biomarkers, and ultimately how to prevent quality defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Neural tube defects – recent advances, unsolved questions and controversies

PubMed Central

Copp, Andrew J.; Stanier, Philip; Greene, Nicholas D. E.

2014-01-01

Neural tube defects (NTDs) are severe congenital malformations affecting around 1 in every 1000 pregnancies. Here we review recent advances and currently unsolved issues in the NTD field. An innovation in clinical management has come from the demonstration that closure of open spina bifida lesions in utero can diminish neurological dysfunction in children. Primary prevention by folic acid has been enhanced through introduction of mandatory food fortification in some countries, although not yet in UK. Genetic predisposition comprises the majority of NTD risk, and genes that regulate folate one-carbon metabolism and planar cell polarity have been strongly implicated. The sequence of human neural tube closure events remains controversial, but study of mouse NTD models shows that anencephaly, open spina bifida and craniorachischisis result from failure of primary neurulation, while skin-covered spinal dysraphism results from defective secondary neurulation. Other ‘NTD’ malformations, such as encephalocele, are likely to be post-neurulation disorders. PMID:23790957

Reconstruction of palatal defect using mucoperiosteal hinge flap and pushback palatoplasty.

PubMed

Lee, S I; Lee, H S; Hwang, K

2001-11-01

This article describes a simple, new surgical technique to provide a complete two-layer closure of palatal defect resulting from a surgical complication of trans palatal resection of skull base chordoma. The nasal layer was reconstructed with triangular shape oral mucoperiosteal turn over hinge flap based on anterior margin of palatal defect and rectangular shaped lateral nasal mucosal hinge flaps. The oral layer was reconstructed with conventional pushback V-Y advancement 2-flaps palatoplasty. Each layer of the flaps were secured with two key mattress suture for flap coaptation. This technique has some advantages: simple, short operation time, one-stage procedure, no need of osteotomy. It can close small- to medium-sized palatal defect of palate or wide cleft palate and can prevent common complication of oronasal fistula, which could be caused by tension.

Modeling Anterior Development in Mice: Diet as Modulator of Risk for Neural Tube Defects

PubMed Central

Kappen, Claudia

2014-01-01

Head morphogenesis is a complex process that is controlled by multiple signaling centers. The most common defects of cranial development are craniofacial defects, such as cleft lip and cleft palate, and neural tube defects, such as anencephaly and encephalocoele in humans. More than 400 genes that contribute to proper neural tube closure have been identified in experimental animals, but only very few causative gene mutations have been identified in humans, supporting the notion that environmental influences are critical. The intrauterine environment is influenced by maternal nutrition, and hence, maternal diet can modulate the risk for cranial and neural tube defects. This article reviews recent progress toward a better understanding of nutrients during pregnancy, with particular focus on mouse models for defective neural tube closure. At least four major patterns of nutrient responses are apparent, suggesting that multiple pathways are involved in the response, and likely in the underlying pathogenesis of the defects. Folic acid has been the most widely studied nutrient, and the diverse responses of the mouse models to folic acid supplementation indicate that folic acid is not universally beneficial, but that the effect is dependent on genetic configuration. If this is the case for other nutrients as well, efforts to prevent neural tube defects with nutritional supplementation may need to become more specifically targeted than previously appreciated. Mouse models are indispensable for a better understanding of nutrient–gene interactions in normal pregnancies, as well as in those affected by metabolic diseases, such as diabetes and obesity. PMID:24124024

A Proposed Defect Tracking Model for Classifying the Inserted Defect Reports to Enhance Software Quality Control

PubMed Central

Khedr, Ayman E.; Sayed, Mostafa

2013-01-01

CONFLICT OF INTEREST: NONE DECLARED Defect tracking systems play an important role in the software development organizations as they can store historical information about defects. There are many research in defect tracking models and systems to enhance their capabilities to be more specifically tracking, and were adopted with new technology. Furthermore, there are different studies in classifying bugs in a step by step method to have clear perception and applicable method in detecting such bugs. This paper shows a new proposed defect tracking model for the purpose of classifying the inserted defects reports in a step by step method for more enhancement of the software quality. PMID:24039334

Molecular genetic studies in a case series of isolated hypoaldosteronism due to biosynthesis defects or aldosterone resistance.

PubMed

Turan, Ihsan; Kotan, Leman Damla; Tastan, Mehmet; Gurbuz, Fatih; Topaloglu, Ali Kemal; Yuksel, Bilgin

2018-06-01

Hypoaldosteronism is associated with either insufficient aldosterone production or aldosterone resistance (pseudohypoaldosteronism). Patients with aldosterone defects typically present with similar symptoms and findings, which include failure to thrive, vomiting, hyponatremia, hyperkalemia and metabolic acidosis. Accurate diagnosis of these clinical conditions therefore can be challenging. Molecular genetic analyses can help to greatly clarify this complexity. The aim of this study was to obtain an overview of the clinical and genetic characteristics of patients with aldosterone defects due to biosynthesis defects or aldosterone resistance. We investigated the clinical and molecular genetic features of 8 consecutive patients with a clinical picture of aldosterone defects seen in our clinics during the period of May 2015 through October 2017. We screened CYP11B2 for aldosterone synthesis defects and NR3C2 and the three EnaC subunits (SCNN1A, SCNN1B and SCNN1G) for aldosterone resistance. We found 4 novel and 2 previously reported mutations in the genes CYP11B2, NR3C2, SCNN1A and SCNN1G in 9 affected individuals from 7 unrelated families. Molecular genetic investigations can help confidently diagnose these conditions and clarify the pathogenicity of aldosterone defects. This study may expand the clinical and genetic correlations of defects in aldosterone synthesis or resistance. © 2018 John Wiley & Sons Ltd.

T Cells Prevent Hemorrhagic Transformation in Ischemic Stroke by P-Selectin Binding.

PubMed

Salas-Perdomo, Angélica; Miró-Mur, Francesc; Urra, Xabier; Justicia, Carles; Gallizioli, Mattia; Zhao, Yashu; Brait, Vanessa H; Laredo, Carlos; Tudela, Raúl; Hidalgo, Andrés; Chamorro, Ángel; Planas, Anna M

2018-06-14

Hemorrhagic transformation is a serious complication of ischemic stroke after recanalization therapies. This study aims to identify mechanisms underlying hemorrhagic transformation after cerebral ischemia/reperfusion. We used wild-type mice and Selplg -/- and Fut7 -/- mice defective in P-selectin binding and lymphopenic Rag2 -/- mice. We induced 30-minute or 45-minute ischemia by intraluminal occlusion of the middle cerebral artery and assessed hemorrhagic transformation at 48 hours with a hemorrhage grading score, histological means, brain hemoglobin content, or magnetic resonance imaging. We depleted platelets and adoptively transferred T cells of the different genotypes to lymphopenic mice. Interactions of T cells with platelets in blood were studied by flow cytometry and image stream technology. We show that platelet depletion increased the bleeding risk only after large infarcts. Lymphopenia predisposed to hemorrhagic transformation after severe stroke, and adoptive transfer of T cells prevented hemorrhagic transformation in lymphopenic mice. CD4 + memory T cells were the subset of T cells binding P-selectin and platelets through functional P-selectin glycoprotein ligand-1. Mice defective in P-selectin binding had a higher hemorrhagic score than wild-type mice. Adoptive transfer of T cells defective in P-selectin binding into lymphopenic mice did not prevent hemorrhagic transformation. The study identifies lymphopenia as a previously unrecognized risk factor for secondary hemorrhagic transformation in mice after severe ischemic stroke. T cells prevent hemorrhagic transformation by their capacity to bind platelets through P-selectin. The results highlight the role of T cells in bridging immunity and hemostasis in ischemic stroke. © 2018 American Heart Association, Inc.

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.

Optically inactive defects in monolayer and bilayer phosphorene: A first-principles study

NASA Astrophysics Data System (ADS)

Huang, Ling-yi; Zhang, Xu; Zhang, Mingliang; Lu, Gang

2018-05-01

Many-body excitonic effect is crucial in two-dimensional (2D) materials and can significantly impact their optoelectronic properties. Because defects are inevitable in 2D materials, understanding how they influence the optical and excitonic properties of the 2D materials is of significant scientific and technological importance. Here we focus on intrinsic point defects in monolayer and bilayer phosphorene and examine whether and how their optoelectronic properties may be modified by the defects. Based on large-scale first-principles calculations, we have systematically explored the optical and excitonic properties of phosphorene in the presence and absence of the point defects. We find that the optical properties of bilayer phosphorene depend on the stacking order of the layers. More importantly, we reveal that the dominant point defects in few-layer phosphorene are optically inactive, which renders phosphorene particularly attractive in optoelectronic applications.

Insights into Metabolic Mechanisms Underlying Folate-Responsive Neural Tube Defects: A Minireview

PubMed Central

Beaudin, Anna E.; Stover, Patrick J.

2015-01-01

Neural tube defects (NTDs), including anencephaly and spina bifida, arise from the failure of neurulation during early embryonic development. Neural tube defects are common birth defects with a heterogenous and multifactorial etiology with interacting genetic and environmental risk factors. Although the mechanisms resulting in failure of neural tube closure are unknown, up to 70% of NTDs can be prevented by maternal folic acid supplementation. However, the metabolic mechanisms underlying the association between folic acid and NTD pathogenesis have not been identified. This review summarizes our current understanding of the mechanisms by which impairments in folate metabolism might ultimately lead to failure of neural tube closure, with an emphasis on untangling the relative contributions of nutritional deficiency and genetic risk factors to NTD pathogenesis. PMID:19180567

Osteogenic Activity of Locally Applied Small Molecule Drugs in a Rat Femur Defect Model

PubMed Central

Cottrell, Jessica A.; Vales, Francis M.; Schachter, Deborah; Wadsworth, Scott; Gundlapalli, Rama; Kapadia, Rasesh; O'Connor, J. Patrick

2010-01-01

The long-term success of arthroplastic joints is dependent on the stabilization of the implant within the skeletal site. Movement of the arthroplastic implant within the bone can stimulate osteolysis, and therefore methods which promote rigid fixation or bone growth are expected to enhance implant stability and the long-term success of joint arthroplasty. In the present study, we used a simple bilateral bone defect model to analyze the osteogenic activity of three small-molecule drug implants via microcomputerized tomography (micro-CT) and histomorphometry. In this study, we show that local delivery of alendronate, but not lovastatin or omeprazole, led to significant new bone formation at the defect site. Since alendronate impedes osteoclast-development, it is theorized that alendronate treatment results in a net increase in bone formation by preventing osteoclast mediated remodeling of the newly formed bone and upregulating osteoblasts. PMID:20625499

Dental enamel defects predict adolescent health indicators: A cohort study among the Tsimane' of Bolivia.

PubMed

Masterson, Erin E; Fitzpatrick, Annette L; Enquobahrie, Daniel A; Mancl, Lloyd A; Eisenberg, Dan T A; Conde, Esther; Hujoel, Philippe P

2018-05-01

Bioarchaeological findings have linked defective enamel formation in preadulthood with adult mortality. We investigated how defective enamel formation in infancy and childhood is associated with risk factors for adult morbidity and mortality in adolescents. This cohort study of 349 Amerindian adolescents (10-17 years of age) related extent of enamel defects on the central maxillary incisors (none, less than 1/3, 1/3 to 2/3, more than 2/3) to adolescent anthropometrics (height, weight) and biomarkers (hemoglobin, glycated hemoglobin, white blood cell count, and blood pressure). Risk differences and 95% confidence intervals were estimated using multiple linear regression. Enamel defects and stunted growth were compared in their ability to predict adolescent health indicators using log-binomial regression and receiver operating characteristics (ROCs). Greater extent of defective enamel formation on the tooth surface was associated with shorter height (-1.35 cm, 95% CI: -2.17, -0.53), lower weight (-0.98 kg, 95% CI: -1.70, -0.26), lower hemoglobin (-0.36 g/dL, 95% CI: -0.59, -0.13), lower glycated hemoglobin (-0.04 %A 1c , 95% CI: -0.08, -0.00008), and higher white blood cell count (0.74 10 9 /L, 95% CI: 0.35, 1.14) in adolescence. Extent of enamel defects and stunted growth independently performed similarly as risk factors for adverse adolescent outcomes, including anemia, prediabetes/type II diabetes, elevated WBC count, prehypertension/hypertension, and metabolic health. Defective enamel formation in infancy and childhood predicted adolescent health outcomes and may be primarily associated with infection. Extent of enamel defects and stunted growth may be equally predictive of adverse adolescent health outcomes. © 2018 Wiley Periodicals, Inc.

[Difficulties of the methods for studying environmental exposure and neural tube defects].

PubMed

Borja-Aburto, V H; Bermúdez-Castro, O; Lacasaña-Navarro, M; Kuri, P; Bustamante-Montes, P; Torres-Meza, V

1999-01-01

To discuss the attitudes in the assessment of environmental exposures as risk factors associated with neural tube defects, and to present the main risk factors studied to date. Environmental exposures have been suggested to have a roll in the genesis of birth defects. However, studies conducted in human populations have found difficulties in the design and conduction to show such an association for neural tube defects (anencephaly, espina bifida and encephalocele) because of problems raised from: a) the frequency measures used to compare time trends and communities, b) the classification of heterogeneous malformations, c) the inclusion of maternal, paternal and fetal factors as an integrated process and, d) the assessment of environmental exposures. Hypothetically both maternal and paternal environmental exposures can produce damage before and after conception by direct action on the embryo and the fetus-placenta complex. Therefore, in the assessment of environmental exposures we need to take into account: a) both paternal and maternal exposures; b) the critical exposure period, three months before conception for paternal exposures and one month around the conceptional period for maternal exposures; c) quantitatively evaluate environmental exposures when possible, avoiding a dichotomous classification; d) the use of biological markers of exposure is highly recommended as well as markers of genetic susceptibility.

Multiscale crystal defect dynamics: A coarse-grained lattice defect model based on crystal microstructure

NASA Astrophysics Data System (ADS)

Lyu, Dandan; Li, Shaofan

2017-10-01

Crystal defects have microstructure, and this microstructure should be related to the microstructure of the original crystal. Hence each type of crystals may have similar defects due to the same failure mechanism originated from the same microstructure, if they are under the same loading conditions. In this work, we propose a multiscale crystal defect dynamics (MCDD) model that models defects by considering its intrinsic microstructure derived from the microstructure or material genome of the original perfect crystal. The main novelties of present work are: (1) the discrete exterior calculus and algebraic topology theory are used to construct a scale-up (coarse-grained) dual lattice model for crystal defects, which may represent all possible defect modes inside a crystal; (2) a higher order Cauchy-Born rule (up to the fourth order) is adopted to construct atomistic-informed constitutive relations for various defect process zones, and (3) an hierarchical strain gradient theory based finite element formulation is developed to support an hierarchical multiscale cohesive (process) zone model for various defects in a unified formulation. The efficiency of MCDD computational algorithm allows us to simulate dynamic defect evolution at large scale while taking into account atomistic interaction. The MCDD model has been validated by comparing of the results of MCDD simulations with that of molecular dynamics (MD) in the cases of nanoindentation and uniaxial tension. Numerical simulations have shown that MCDD model can predict dislocation nucleation induced instability and inelastic deformation, and thus it may provide an alternative solution to study crystal plasticity.

Maternal use of folic acid supplements and infant risk of neural tube defects in Norway 1999-2013.

PubMed

Gildestad, Trude; Øyen, Nina; Klungsøyr, Kari; Nilsen, Roy Miodini; Daltveit, Anne Kjersti; Vollset, Stein Emil

2016-08-01

Like most European countries, Norway has refrained from mandatory food fortification with folic acid to reduce the number of neural tube defects. We explored the role of folic acid and multivitamin supplements in the prevention of neural tube defects among newborn infants. We used data from the Medical Birth Registry of Norway, 1999-2013. A total of 528,220 women had 880,568 pregnancies resulting in 896,674 live- and stillborn infants, of whom 270 had neural tube defects. Relative risks were estimated with log-binomial regression. From 1999 to 2013, intake of folic acid supplements increased from 4.8% to 27.4%. Vitamin supplement use was more frequent in older, married or cohabiting women and those with lower parity, as well as women who did not smoke during pregnancy. The overall adjusted relative risk of infant neural tube defects associated with maternal vitamin intake before pregnancy relative to no intake was 0.76 (95% confidence interval: 0.53-1.10). When we divided our study period in two (1999-2005 and 2006-2013), we found a significantly reduced risk of neural tube defects overall by vitamin use in the second time period, but not in the first: adjusted relative risk 0.54 (95% confidence interval: 0.31-0.91) and 1.02 (95% confidence interval: 0.63-1.65), respectively. OVER THE FULL STUDY PERIOD, WE FOUND NO STATISTICALLY SIGNIFICANT ASSOCIATION BETWEEN VITAMIN USE AND NEURAL TUBE DEFECTS OVERALL HOWEVER, VITAMIN USE WAS ASSOCIATED WITH A SIGNIFICANTLY LOWER RISK OF NEURAL TUBE DEFECTS IN THE SECOND HALF OF THE STUDY PERIOD, 2006-2013. © 2016 the Nordic Societies of Public Health.

Heat-Treatment of Defective UiO-66 from Modulated Synthesis: Adsorption and Stability Studies

DOE PAGES

Jiao, Yang; Liu, Yang; Zhu, Guanghui; ...

2017-09-21

Defect engineering in metal–organic frameworks (MOFs) is an emerging strategy that can be used to control physical or chemical characteristics of MOFs, including adsorption behavior and textural, mechanical, and conductive properties. Understanding the impact of defects on textural properties and chemical stability of MOFs is imperative to the development of MOFs with tunable defect sites. In this work, systematic adsorption measurements were performed with three adsorbate molecules (SO 2, benzene, and cyclohexane) to investigate changes in the pore size of defective UiO-66. Compared to the parent UiO-66, the defective UiO-66 shows significant changes in adsorption capacities among the selected adsorbatemore » molecules, demonstrating that pore size is significantly enlarged by the missing cluster defects. BET surface area analysis and DFT calculations were also performed to interrogate the chemical stability of the defective MOFs after exposure to water and acidic environments. This work shows that pore size can be tuned as a function of defect concentration. Further, it is shown that the structural incorporation of trifluoroacetate groups in defective UiO-66 leads to an increase in average pore size without sacrificing chemical stability toward water and acidic species. The results of this work advance the understanding of textural properties and chemical stability of defect-engineered MOFs and also suggest a preparation method for synthesizing defective but stable MOFs.« less

Fetal Alcohol Spectrum Disorder (FASD) Associated Neural Defects: Complex Mechanisms and Potential Therapeutic Targets

PubMed Central

Muralidharan, Pooja; Sarmah, Swapnalee; Zhou, Feng C.; Marrs, James A.

2013-01-01

Fetal alcohol spectrum disorder (FASD), caused by prenatal alcohol exposure, can result in craniofacial dysmorphism, cognitive impairment, sensory and motor disabilities among other defects. FASD incidences are as high as 2% to 5 % children born in the US, and prevalence is higher in low socioeconomic populations. Despite various mechanisms being proposed to explain the etiology of FASD, the molecular targets of ethanol toxicity during development are unknown. Proposed mechanisms include cell death, cell signaling defects and gene expression changes. More recently, the involvement of several other molecular pathways was explored, including non-coding RNA, epigenetic changes and specific vitamin deficiencies. These various pathways may interact, producing a wide spectrum of consequences. Detailed understanding of these various pathways and their interactions will facilitate the therapeutic target identification, leading to new clinical intervention, which may reduce the incidence and severity of these highly prevalent preventable birth defects. This review discusses manifestations of alcohol exposure on the developing central nervous system, including the neural crest cells and sensory neural placodes, focusing on molecular neurodevelopmental pathways as possible therapeutic targets for prevention or protection. PMID:24961433

Fetal Alcohol Spectrum Disorder (FASD) Associated Neural Defects: Complex Mechanisms and Potential Therapeutic Targets.

PubMed

Muralidharan, Pooja; Sarmah, Swapnalee; Zhou, Feng C; Marrs, James A

2013-06-19

Fetal alcohol spectrum disorder (FASD), caused by prenatal alcohol exposure, can result in craniofacial dysmorphism, cognitive impairment, sensory and motor disabilities among other defects. FASD incidences are as high as 2% to 5 % children born in the US, and prevalence is higher in low socioeconomic populations. Despite various mechanisms being proposed to explain the etiology of FASD, the molecular targets of ethanol toxicity during development are unknown. Proposed mechanisms include cell death, cell signaling defects and gene expression changes. More recently, the involvement of several other molecular pathways was explored, including non-coding RNA, epigenetic changes and specific vitamin deficiencies. These various pathways may interact, producing a wide spectrum of consequences. Detailed understanding of these various pathways and their interactions will facilitate the therapeutic target identification, leading to new clinical intervention, which may reduce the incidence and severity of these highly prevalent preventable birth defects. This review discusses manifestations of alcohol exposure on the developing central nervous system, including the neural crest cells and sensory neural placodes, focusing on molecular neurodevelopmental pathways as possible therapeutic targets for prevention or protection.

A review of defects and disorder in multinary tetrahedrally bonded semiconductors [Defects and disorder in multinary tetrahedrally bonded semiconductors studied by experiment and theory

DOE PAGES

Baranowski, Lauryn L.; Zawadzki, Pawel; Lany, Stephan; ...

2016-11-10

Defects are critical to understanding the electronic properties of semiconducting compounds, for applications such as light-emitting diodes, transistors, photovoltaics, and thermoelectrics. In this review, we describe our work investigating defects in tetrahedrally bonded, multinary semiconductors, and discuss the place of our research within the context of publications by other groups. We applied experimental and theory techniques to understand point defects, structural disorder, and extended antisite defects in one semiconductor of interest for photovoltaic applications, Cu 2SnS 3. We contrast our findings on Cu 2SnS 3 with other chemically related Cu-Sn-S compounds, as well as structurally related compounds such as Cumore » 2ZnSnS 4 and Cu(In,Ga)Se 2. We find that evaluation of point defects alone is not sufficient to understand defect behavior in multinary tetrahedrally bonded semiconductors. In the case of Cu 2SnS 3 and Cu 2ZnSnS 4, structural disorder and entropy-driven cation clustering can result in nanoscale compositional inhomogeneities which detrimentally impact the electronic transport. Therefore, it is not sufficient to assess only the point defect behavior of new multinary tetrahedrally bonded compounds; effects such as structural disorder and extended antisite defects must also be considered. Altogether, this review provides a framework for evaluating tetrahedrally bonded semiconducting compounds with respect to their defect behavior for photovoltaic and other applications, and suggests new materials that may not be as prone to such imperfections.« less

A review of defects and disorder in multinary tetrahedrally bonded semiconductors [Defects and disorder in multinary tetrahedrally bonded semiconductors studied by experiment and theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baranowski, Lauryn L.; Zawadzki, Pawel; Lany, Stephan

Defects are critical to understanding the electronic properties of semiconducting compounds, for applications such as light-emitting diodes, transistors, photovoltaics, and thermoelectrics. In this review, we describe our work investigating defects in tetrahedrally bonded, multinary semiconductors, and discuss the place of our research within the context of publications by other groups. We applied experimental and theory techniques to understand point defects, structural disorder, and extended antisite defects in one semiconductor of interest for photovoltaic applications, Cu 2SnS 3. We contrast our findings on Cu 2SnS 3 with other chemically related Cu-Sn-S compounds, as well as structurally related compounds such as Cumore » 2ZnSnS 4 and Cu(In,Ga)Se 2. We find that evaluation of point defects alone is not sufficient to understand defect behavior in multinary tetrahedrally bonded semiconductors. In the case of Cu 2SnS 3 and Cu 2ZnSnS 4, structural disorder and entropy-driven cation clustering can result in nanoscale compositional inhomogeneities which detrimentally impact the electronic transport. Therefore, it is not sufficient to assess only the point defect behavior of new multinary tetrahedrally bonded compounds; effects such as structural disorder and extended antisite defects must also be considered. Altogether, this review provides a framework for evaluating tetrahedrally bonded semiconducting compounds with respect to their defect behavior for photovoltaic and other applications, and suggests new materials that may not be as prone to such imperfections.« less

Hydroxyapatite nanobelt/polylactic acid Janus membrane with osteoinduction/barrier dual functions for precise bone defect repair.

PubMed

Ma, Baojin; Han, Jing; Zhang, Shan; Liu, Feng; Wang, Shicai; Duan, Jiazhi; Sang, Yuanhua; Jiang, Huaidong; Li, Dong; Ge, Shaohua; Yu, Jinghua; Liu, Hong

2018-04-15

Controllable osteoinduction maintained in the original defect area is the key to precise bone repair. To meet the requirement of precise bone regeneration, a hydroxyapatite (HAp) nanobelt/polylactic acid (PLA) (HAp/PLA) Janus membrane has been successfully prepared in this study by coating PLA on a paper-like HAp nanobelt film by a casting-pervaporation method. The Janus membrane possesses dual functions: excellent osteoinduction from the hydrophilic HAp nanobelt side and barrier function originating from the hydrophobic PLA film. The cell viability and osteogenic differentiation ability of human adipose-derived stem cells (hADSCs) on the Janus membrane were assessed. The in vitro experimental results prove that the HAp nanobelt side presents high cell viability and efficient osteoinduction without any growth factor and that the PLA side can prohibit cell attachment. The in vivo repair experiments on a rat mandible defect model prove that the PLA side can prevent postoperative adhesion between bone and adjacent soft tissues. Most importantly, the HAp side has a strong ability to promote defect repair and bone regeneration. Therefore, the HAp/PLA Janus membrane will have wide applications as a kind of tissue engineering material in precise bone repair because of its unique dual osteoinduction/barrier functions, biocompatibility, low cost, and its ability to be mass-produced. Precise bone defect repair to keeping tissue integrity and original outline shape is a very important issue for tissue engineering. Here, we have designed and prepared a novel HAp/PLA Janus membrane using a casting-pervaporation method to form a layer of PLA film on paper-like HAp nanobelt film. HAp nanobelt side of the Janus membrane can successfully promote osteogenic differentiation. PLA side of the Janus membrane exhibits good properties as a barrier for preventing the adhesion of cells in vitro. Mandible repair experiments in vivo have shown that the HAp/PLA Janus membrane can promote rat

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

PubMed Central

König, Thomas; Simon, Georg H; Heinke, Lars; Lichtenstein, Leonid

2011-01-01

Summary 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., F0, F+, F2+ 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 F2+-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. PMID:21977410

Epidemiology of neural tube defects in Saudi Arabia.

PubMed

AlShail, Essam; De Vol, Edward; Yassen, Ahsan; Elgamal, Essam A

2014-12-01

To evaluate the distribution and pattern of neural tube defects in Saudi Arabia by creating a hospital based registry. All cases registered in the King Faisal Specialist Hospital and Research Center (KFSH&RC) neural tube defect (NTD) registry since it was established in October 2000 until December 2012 were studied through active surveillance comprising a registrar who collects NTD information by reviewing the patient's medical records, and interviewing patient's families. The total number of patients registered from October 2000 to December 2012 was 718 patients. There were more females (417, 58%) than males (301, 42%). Of 620 mothers who underwent antenatal ultrasonography; 392 (63%) were diagnosed at birth, and 204 (33%) were diagnosed with antenatal hydrocephalus. In our registry sample, most mothers (95%) did not take folic acid 3 months prior to pregnancy, and 76% did not take folic acid during the 3 months after conception with the affected child. Only 5% received folic acid prior to conception. The KFSH&RC-NTD registry has met its objectives as a source of data that may significantly contribute to the prevention of NTDs, and improving quality of care for NTD patients through active publication of registry findings and management approaches.

Prevention and Treatment of Esophageal Stenosis after Endoscopic Submucosal Dissection for Early Esophageal Cancer

PubMed Central

Wen, Jing; Lu, Zhongsheng; Liu, Qingsen

2014-01-01

Endoscopic submucosal dissection (ESD) for the treatment of esophageal mucosal lesions is associated with a risk of esophageal stenosis, especially for near-circumferential or circumferential esophageal mucosal defects. Here, we review historic and modern studies on the prevention and treatment of esophageal stenosis after ESD. These methods include prevention via pharmacological treatment, endoscopic autologous cell transplantation, endoscopic esophageal dilatation, and stent placement. This short review will focus on direct prevention and treatment, which may help guide the way forward. PMID:25386186

Transcatheter Retrieval of Embolized Atrial Septal Defect Occluder Device by Waist Capture Technique.

PubMed

Her, Ae-Young; Lim, Kyung-Hun; Shin, Eun-Seok

2018-01-27

This case study describes the successful percutaneous transcatheter retrieval of an embolized Amplatzer occluder device using the "waist capture technique" in a patient with an atrial septal defect. This technique allowed for stability of the Amplatzer device, compression of the atrial discs for easier removal, prevention of further embolization, and minimal injury to vasculature during device retrieval. This novel and effective technique can be used safely for the retrieval of Amplatzer devices in the venous system.

Defect characterization in Mg-doped GaN studied using a monoenergetic positron beam

NASA Astrophysics Data System (ADS)

Uedono, A.; Ishibashi, S.; Tenjinbayashi, K.; Tsutsui, T.; Nakahara, K.; Takamizu, D.; Chichibu, S. F.

2012-01-01

Vacancy-type defects in Mg-doped GaN grown by metalorganic vapor phase epitaxy were probed using a monoenergetic positron beam. For a sample fabricated with a high H2-flow rate, before post-growth annealing the major defect species detected by positrons was identified as vacancy-clusters. Evidence suggested that other donor-type defects such as nitrogen vacancies also existed. The defects increased the Fermi level position, and enhanced the diffusion of positrons toward the surface. The annihilation of positrons at the top surface was suppressed by Mg-doping. This was attributed to the introduction of a subsurface layer (<6 nm) with a low defect concentration, where the Fermi level position was considered to decrease due to partial activation of Mg. For samples after annealing, the trapping of positrons by residual vacancy-type defects was observed, and the sample crystal quality was found to depend on that before annealing.

Surgery for doubly committed ventricular septal defects.

PubMed

Shamsuddin, Ahmad Mahir; Chen, Yen Chuan; Wong, Abdul Rahim; Le, Trong-Phi; Anderson, Robert H; Corno, Antonio F

2016-08-01

Doubly committed ventricular septal defects (VSDs) account for up to almost one-third of isolated ventricular septal defects in Asian countries, compared with only 1/20th in western populations. In our surgical experience, this type of defect accounted for almost three-quarters of our practice. To date, patch closure has been considered the gold standard for surgical treatment of these lesions. Our objectives are to evaluate the indications and examine the outcomes of surgery for doubly committed VSDs. Between October 2013, when our service of paediatric cardiac surgery was opened, and December 2014, 24 patients were referred for surgical closure of VSDs. Among them, 17 patients (71%), with the median age of 6 years, ranging from 2 to 9 years, and with a median body weight of 19 kg, ranging from 11 to 56 kg, underwent surgical repair for doubly committed defects. In terms of size, the defect was considered moderate in 4 and large in 13. Aortic valvular regurgitation (AoVR) was present in 11 patients (65%) preoperatively, with associated malformations found in 14 (82%), with 5 patients (29%) having two or more associated defects. After surgery, there was trivial residual shunting in 2 patients (12%). AoVR persisted in 6 (35%), reducing to trivial in 5 (29%) and mild in 1 (6%). Mean stays in the intensive care unit and hospital were 2.6 ± 1.2 days, ranging from 2 to 7 days, and 6.8 ± 0.8 days, ranging from 6 to 9 days, respectively. The mean follow-up was 14 ± 4 months, ranging from 6 to 20 months, with no early or late deaths and without clinical deterioration. The incidence of doubly committed lesions is high in our experience, frequently associated with AoVR and other associated malformation. Early detection is crucial to prevent further progression of the disease. Patch closure remains the gold standard in management, not least since it allows simultaneous repair of associated intracardiac defects. © The Author 2016. Published by Oxford University Press on

Low carbohydrate diets may increase risk of neural tube defects.

PubMed

Desrosiers, Tania A; Siega-Riz, Anna Maria; Mosley, Bridget S; Meyer, Robert E

2018-01-25

Folic acid fortification significantly reduced the prevalence of neural tube defects (NTDs) in the United States. The popularity of "low carb" diets raises concern that women who intentionally avoid carbohydrates, thereby consuming fewer fortified foods, may not have adequate dietary intake of folic acid. To assess the association between carbohydrate intake and NTDs, we analyzed data from the National Birth Defects Prevention Study from 1,740 mothers of infants, stillbirths, and terminations with anencephaly or spina bifida (cases), and 9,545 mothers of live born infants without a birth defect (controls) conceived between 1998 and 2011. Carbohydrate and folic acid intake before conception were estimated from food frequency questionnaire responses. Restricted carbohydrate intake was defined as ≤5th percentile among controls. Odds ratios were estimated with logistic regression and adjusted for maternal race/ethnicity, education, alcohol use, folic acid supplement use, study center, and caloric intake. Mean dietary intake of folic acid among women with restricted carbohydrate intake was less than half that of other women (p < .01), and women with restricted carbohydrate intake were slightly more likely to have an infant with an NTD (AOR = 1.30, 95% CI: 1.02, 1.67). This is the first study to examine the association between carbohydrate intake and NTDs among pregnancies conceived postfortification. We found that women with restricted carbohydrate intake were 30% more likely to have an infant with anencephaly or spina bifida. However, more research is needed to understand the pathways by which restricted carbohydrate intake might increase the risk of NTDs. © 2018 Wiley Periodicals, Inc.

SEMATECH produces defect-free EUV mask blanks: defect yield and immediate challenges

NASA Astrophysics Data System (ADS)

Antohe, Alin O.; Balachandran, Dave; He, Long; Kearney, Patrick; Karumuri, Anil; Goodwin, Frank; Cummings, Kevin

2015-03-01

Availability of defect-free reflective mask has been one of the most critical challenges to extreme ultraviolet lithography (EUVL). To mitigate the risk, significant progress has been made on defect detection, pattern shifting, and defect repair. Clearly such mitigation strategies are based on the assumption that defect counts and sizes from incoming mask blanks must be below practical levels depending on mask specifics. The leading industry consensus for early mask product development is that there should be no defects greater than 80 nm in the quality area, 132 mm x 132 mm. In addition less than 10 defects smaller than 80 nm may be mitigable. SEMATECH has been focused on EUV mask blank defect reduction using Veeco Nexus TM IBD platform, the industry standard for mask blank production, and assessing if IBD technology can be evolved to a manufacturing solution. SEMATECH has recently announced a breakthrough reduction of defects in the mask blank deposition process resulting in the production of two defect-free EUV mask blanks at 54 nm inspection sensitivity (SiO2 equivalent). This paper will discuss the dramatic reduction of baseline EUV mask blank defects, review the current deposition process run and compare results with previous process runs. Likely causes of remaining defects will be discussed based on analyses as characterized by their compositions and whether defects are embedded in the multilayer stack or non-embedded.

Parametric study using modal analysis of a bi-material plate with defects

NASA Astrophysics Data System (ADS)

Esola, S.; Bartoli, I.; Horner, S. E.; Zheng, J. Q.; Kontsos, A.

2015-03-01

Global vibrational method feasibility as a non-destructive inspection tool for multi-layered composites is evaluated using a simulated parametric study approach. A finite element model of a composite consisting of two, isotropic layers of dissimilar materials and a third, thin isotropic layer of adhesive is constructed as the representative test subject. Next, artificial damage is inserted according to systematic variations of the defect morphology parameters. A free-vibrational modal analysis simulation is executed for pristine and damaged plate conditions. Finally, resultant mode shapes and natural frequencies are extracted, compared and analyzed for trends. Though other defect types may be explored, the focus of this research is on interfacial delamination and its effects on the global, free-vibrational behavior of a composite plate. This study is part of a multi-year research effort conducted for the U.S. Army Program Executive Office - Soldier.

Phonons, defects and optical damage in crystalline acetanilide

NASA Astrophysics Data System (ADS)

Kosic, Thomas J.; Hill, Jeffrey R.; Dlott, Dana D.

1986-04-01

Intense picosecond pulses cause accumulated optical damage in acetanilide crystals at low temperature. Catastrophic damage to the irradiated volume occurs after an incubation period where defects accumulate. The optical damage is monitored with subanosecond time resolution. The generation of defects is studied with damage-detected picosecond spectroscopy. The accumulation of defects is studied by time-resolved coherent Raman scattering, which is used to measure optical phonon scattering from the accumulating defects.

Study on growth techniques and macro defects of large-size Nd:YAG laser crystal

NASA Astrophysics Data System (ADS)

Quan, Jiliang; Yang, Xin; Yang, Mingming; Ma, Decai; Huang, Jinqiang; Zhu, Yunzhong; Wang, Biao

2018-02-01

Large-size neodymium-doped yttrium aluminum garnet (Nd:YAG) single crystals were grown by the Czochralski method. The extinction ratio and wavefront distortion of the crystal were tested to determine the optical homogeneity. Moreover, under different growth conditions, the macro defects of inclusion, striations, and cracking in the as-grown Nd:YAG crystals were analyzed. Specifically, the inclusion defects were characterized using scanning electron microscopy and energy dispersive spectroscopy. The stresses of growth striations and cracking were studied via a parallel plane polariscope. These results demonstrate that improper growth parameters and temperature fields can enhance defects significantly. Thus, by adjusting the growth parameters and optimizing the thermal environment, high-optical-quality Nd:YAG crystals with a diameter of 80 mm and a total length of 400 mm have been obtained successfully.

Dental Caries and Enamel Defects in Very Low Birth Weight Adolescents

PubMed Central

Nelson, S.; Albert, J.M.; Lombardi, G.; Wishnek, S.; Asaad, G.; Kirchner, H.L.; Singer, L.T.

2011-01-01

Objectives The purpose of this study was to examine developmental enamel defects and dental caries in very low birth weight adolescents with high risk (HR-VLBW) and low risk (LR-VLBW) compared to full-term (term) adolescents. Methods The sample consisted of 224 subjects (80 HR-VLBW, 59 LR-VLBW, 85 term adolescents) recruited from an ongoing longitudinal study. Sociodemographic and medical information was available from birth. Dental examination of the adolescent at the 14-year visit included: enamel defects (opacity and hypoplasia); decayed, missing, filled teeth of incisors and molars (DMFT-IM) and of overall permanent teeth (DMFT); Simplified Oral Hygiene Index for debris/calculus on teeth, and sealant presence. A caregiver questionnaire completed simultaneously assessed dental behavior, access, insurance status and prevention factors. Hierarchical analysis utilized the zero-inflated negative binomial model and zero-inflated Poisson model. Results The zero-inflated negative binomial model controlling for sociodemographic variables indicated that the LR-VLBW group had an estimated 75% increase (p < 0.05) in number of demarcated opacities in the incisors and first molar teeth compared to the term group. Hierarchical modeling indicated that demarcated opacities were a significant predictor of DMFT-IM after control for relevant covariates. The term adolescents had significantly increased DMFT-IM and DMFT scores compared to the LR-VLBW adolescents. Conclusion LR-VLBW was a significant risk factor for increased enamel defects in the permanent incisors and first molars. Term children had increased caries compared to the LR-VLBW group. The effect of birth group and enamel defects on caries has to be investigated longitudinally from birth. PMID:20975268

Topological defects in epithelia govern cell death and extrusion

NASA Astrophysics Data System (ADS)

Saw, Thuan Beng; Doostmohammadi, Amin; Nier, Vincent; Kocgozlu, Leyla; Thampi, Sumesh; Toyama, Yusuke; Marcq, Philippe; Lim, Chwee Teck; Yeomans, Julia M.; Ladoux, Benoit

2017-04-01

Epithelial tissues (epithelia) remove excess cells through extrusion, preventing the accumulation of unnecessary or pathological cells. The extrusion process can be triggered by apoptotic signalling, oncogenic transformation and overcrowding of cells. Despite the important linkage of cell extrusion to developmental, homeostatic and pathological processes such as cancer metastasis, its underlying mechanism and connections to the intrinsic mechanics of the epithelium are largely unexplored. We approach this problem by modelling the epithelium as an active nematic liquid crystal (that has a long range directional order), and comparing numerical simulations to strain rate and stress measurements within monolayers of MDCK (Madin Darby canine kidney) cells. Here we show that apoptotic cell extrusion is provoked by singularities in cell alignments in the form of comet-shaped topological defects. We find a universal correlation between extrusion sites and positions of nematic defects in the cell orientation field in different epithelium types. The results confirm the active nematic nature of epithelia, and demonstrate that defect-induced isotropic stresses are the primary precursors of mechanotransductive responses in cells, including YAP (Yes-associated protein) transcription factor activity, caspase-3-mediated cell death, and extrusions. Importantly, the defect-driven extrusion mechanism depends on intercellular junctions, because the weakening of cell-cell interactions in an α-catenin knockdown monolayer reduces the defect size and increases both the number of defects and extrusion rates, as is also predicted by our model. We further demonstrate the ability to control extrusion hotspots by geometrically inducing defects through microcontact printing of patterned monolayers. On the basis of these results, we propose a mechanism for apoptotic cell extrusion: spontaneously formed topological defects in epithelia govern cell fate. This will be important in predicting

Genotype-phenotype relationships in human red/green color-vision defects: molecular and psychophysical studies.

PubMed Central

Deeb, S S; Lindsey, D T; Hibiya, Y; Sanocki, E; Winderickx, J; Teller, D Y; Motulsky, A G

1992-01-01

The relationship between the molecular structure of the X-linked red and green visual pigment genes and color-vision phenotype as ascertained by anomaloscopy was studied in 64 color-defective males. The great majority of red-green defects were associated with either the deletion of the green-pigment gene or the formation of 5' red-green hybrid genes or 5' green-red hybrid genes. A rapid PCR-based method allowed detection of hybrid genes, including those undetectable by Southern blot analysis, as well as more precise localization of the fusion points in hybrid genes. Protan color-vision defects appeared always associated with 5' red-green hybrid genes. Carriers of single red-green hybrid genes with fusion in introns 1-4 were protanopes. However, carriers of hybrid genes with red-green fusions in introns 2, 3, or 4 in the presence of additional normal green genes manifested as either protanopes or protanomalous trichromats, with the majority being protanomalous. Deutan defects were associated with green-pigment gene deletions, with 5' green-red hybrid genes, or, rarely, with 5' green-red-green hybrid genes. Complete green-pigment gene deletions or green-red fusions in intron 1 were usually associated with deuteranopia, although we unexpectedly found three carriers of a single red-pigment gene without any green-pigment genes to be deuteranomalous trichromats. All but one of the other deuteranomalous subjects had green-red hybrid genes with intron 1, 2, 3, or 4 fusions, as well as several normal green-pigment genes. The one exception had a grossly normal gene array, presumably with a more subtle mutation. Amino acid differences in exon 5 largely determine whether a hybrid gene will be more redlike or more greenlike in phenotype. Various discrepancies as to severity (dichromacy or trichromacy) remain unexplained but may arise because of variability of expression, postreceptoral variation, or both. When phenotypic color-vision defects exist, the kind of defect (protan or

Prevention of Tartrate Crystallization in Wine by Hydrocolloids: The Mechanism Studied by Dynamic Light Scattering.

PubMed

Lankhorst, Peter P; Voogt, Benjamin; Tuinier, Remco; Lefol, Blandine; Pellerin, Patrice; Virone, Cristiana

2017-10-11

Young wines are supersaturated in potassium bitartrate, which induces rather uncontrolled crystallization processes. Delayed crystallization may occur even after bottling of the young wines, which is undesirable because it gives rise to a visual defect in the wine. Colloids such as mannoproteins, metatartaric acid, and carboxymethylcellulose are available on the market and may be added to delay crystallization. It has been a matter of debate whether such hydrocolloids prevent nucleation, growth of crystals, or both. It was the objective of this investigation to study the crystallization event by a new approach using dynamic light scattering and to clarify the mode of action of these hydrocolloids. To achieve this, model solutions and standardized wines were enriched with potassium bitartrate (KHT) to trigger crystallization. In this way, it was possible to distinguish between the influence of the hydrocolloids on nucleation and on crystal growth. It was found that the hydrocolloids do not prevent KHT nucleation. Instead, these compounds delay or even arrest the outgrowth of the crystals to a macroscopic, visual size.

Enzyme Replacement for Craniofacial Skeletal Defects and Craniosynostosis in Murine Hypophosphatasia

PubMed Central

Liu, Jin; Campbell, Cassie; Nam, Hwa Kyung; Caron, Alexandre; Yadav, Manisha C; Millán, José Luis; Hatch, Nan E.

2015-01-01

Hypophosphatasia (HPP) is an inborn-error-of-metabolism disorder characterized by deficient bone and tooth mineralization due to loss-of function mutations in the gene (Alpl) encoding tissue-nonspecific alkaline phosphatase (TNAP). Alpl−/− mice exhibit many characteristics seen in infantile HPP including long bone and tooth defects, vitamin B6 responsive seizures and craniosynostosis. Previous reports demonstrated that a mineral-targeted form of TNAP rescues long bone, verterbral and tooth mineralization defects in Alpl−/− mice. Here we report that enzyme replacement with mineral-targeted TNAP (asfotase-alfa) also prevents craniosynostosis (the premature fusion of cranial bones) and additional craniofacial skeletal abnormalities in Alpl−/− mice. Craniosynostosis, cranial bone volume and density, and craniofacial shape abnormalities were assessed by microsocopy, histology, digital caliper measurements and micro CT. We found that craniofacial shape defects, cranial bone mineralization and craniosynostosis were corrected in Alpl−/− mice injected daily subcutaneously starting at birth with recombinant enzyme. Analysis of Alpl−/− calvarial cells indicates that TNAP deficiency leads to aberrant osteoblastic gene expression and diminished proliferation. Some but not all of these cellular abnormalities were rescued by treatment with inorganic phosphate. These results confirm an essential role for TNAP in craniofacial skeletal development and demonstrate the efficacy of early postnatal mineral-targeted enzyme replacement for preventing craniofacial abnormalities including craniosynostosis in murine infantile HPP. PMID:25959417

Prosthetic Rehabilitation of Defects of the Head and Neck

PubMed Central

Salinas, Thomas J.

2010-01-01

Patients afflicted with head and neck cancer, traumatic injuries to the head and neck, or those with congenital or developmental defects benefit from multidisciplinary team management. The head and neck region participates in complex physiologic processes that can often be impeded by these circumstances. Evaluation of the patient by the maxillofacial prosthodontist can assist the other members of the team in providing treatment planning options for the patients. Intraoral defects arising from these circumstances can be treated with prosthodontics that serve to assist with speech, swallowing, and to some degree mastication. If chemotherapeutic or radiation modalities are also used to treat the head and neck, assessment of the patient by the maxillofacial prosthodontist may prove to identify factors that may predispose to undesirable sequelae. Preventive treatment by elective tooth extraction, prosthodontic assessment, and patient education prove to assist in predictable management of these oftentimes complex presenting conditions. Facial defects arising from similar circumstances can be an alternative or adjunct to plastic surgical reconstruction and offer the added advantage of tumor surveillance in susceptible patients. PMID:22550451

Exploring the seasonality of birth defects in the New York State Congenital Malformations Registry.

PubMed

Caton, Alissa R

2012-06-01

Examining seasonal patterns of birth defects may help to identify environmental risk factors. Because the teratogenic window for most birth defects is during gestational weeks 3 to 8, investigating exposures closer to the timing of conception is important. However, studies are usually based on month of birth, which is not the biologically relevant exposure period and does not account for differences in gestational length. We aimed to determine whether the occurrence of birth defects varied by month of conception using the population-based New York State Congenital Malformations Registry (CMR). We merged live birth certificates (n = 2,044,091) with CMR records for mothers residing in New York State, excluding New York City, for the years 1992 through 2006. We categorized birth defects according to the National Birth Defects Prevention Network guidelines and performed Cochran-Armitage trend, Hewitt-Rogerson, and Walter-Elwood tests on month of conception and chi-square tests on season of conception. We graphed seasonal distributions and seasonality test results. We performed stratified analyses by maternal and infant characteristics. Of 42 groups examined in the 15-year period, 24 (57%) had at least one statistically significant test result, suggesting a trend or seasonal variation: Cochran-Armitage (18), Hewitt-Rogerson (17), Walter-Elwood (4), and chi-square (5). Ventricular septal defect showed the most consistent results: Cochran-Armitage (p = 0.0006), Hewitt-Rogerson (December to May; p = 0.0130), Walter-Elwood (March 14; p = 0.0027), and chi-square (winter; p = 0.0046). Congenital cataract, pulmonary valve atresia/stenosis, coarctation of aorta, biliary atresia, and renal agenesis or hypoplasia had at least three significant tests. These results may help to generate hypotheses about environmental factors that vary by season for further studies. Copyright © 2012 Wiley Periodicals, Inc.

Mean Glenoid Defect Size and Location Associated With Anterior Shoulder Instability

PubMed Central

Gottschalk, Lionel J.; Bois, Aaron J.; Shelby, Marcus A.; Miniaci, Anthony; Jones, Morgan H.

2017-01-01

Background: There is a strong correlation between glenoid defect size and recurrent anterior shoulder instability. A better understanding of glenoid defects could lead to improved treatments and outcomes. Purpose: To (1) determine the rate of reporting numeric measurements for glenoid defect size, (2) determine the consistency of glenoid defect size and location reported within the literature, (3) define the typical size and location of glenoid defects, and (4) determine whether a correlation exists between defect size and treatment outcome. Study Design: Systematic review; Level of evidence, 4. Methods: PubMed, Ovid, and Cochrane databases were searched for clinical studies measuring glenoid defect size or location. We excluded studies with defect size requirements or pathology other than anterior instability and studies that included patients with known prior surgery. Our search produced 83 studies; 38 studies provided numeric measurements for glenoid defect size and 2 for defect location. Results: From 1981 to 2000, a total of 5.6% (1 of 18) of the studies reported numeric measurements for glenoid defect size; from 2001 to 2014, the rate of reporting glenoid defects increased to 58.7% (37 of 63). Fourteen studies (n = 1363 shoulders) reported defect size ranges for percentage loss of glenoid width, and 9 studies (n = 570 shoulders) reported defect size ranges for percentage loss of glenoid surface area. According to 2 studies, the mean glenoid defect orientation was pointing toward the 3:01 and 3:20 positions on the glenoid clock face. Conclusion: Since 2001, the rate of reporting numeric measurements for glenoid defect size was only 58.7%. Among studies reporting the percentage loss of glenoid width, 23.6% of shoulders had a defect between 10% and 25%, and among studies reporting the percentage loss of glenoid surface area, 44.7% of shoulders had a defect between 5% and 20%. There is significant variability in the way glenoid bone loss is measured, calculated

A theoretical study of the stability of anionic defects in cubic ZrO 2 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 ZrO 2. 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 formationmore » 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.« less

Neural Tube Defects

MedlinePlus

Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the ... that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In ...

Ambient Air Pollution and Traffic Exposures and Congenital Heart Defects in the San Joaquin Valley of California

PubMed Central

Padula, Amy M.; Tager, Ira B.; Carmichael, Suzan L.; Hammond, S. Katharine; Yang, Wei; Lurmann, Frederick; Shaw, Gary M.

2013-01-01

Background Congenital anomalies are a leading cause of infant morbidity and mortality. Studies suggest associations between environmental contaminants and some anomalies, although evidence is limited. Methods We used data from the California Center of the National Birth Defects Prevention Study and the Children's Health and Air Pollution Study to estimate the odds of 27 congenital heart defects with respect to quartiles of 7 ambient air pollutant and traffic exposures in California during the first two months of pregnancy, 1997–2006 (N=813 cases and N=828 controls). Results Particulate matter <10 microns (PM10) was associated with pulmonary valve stenosis (aOR4th Quartile=2.6; 95% CI: 1.2, 5.7) and perimembranous ventricular septal defects (aOR3rd Quartile=2.1; 95% CI: 1.1, 3.9) after adjusting for maternal race-ethnicity, education and multivitamin use. PM2.5 was associated with transposition of the great arteries (aOR3rd Quartile=2.6; 95% CI: 1.1, 6.5) and inversely associated with perimembranous ventricular septal defects (aOR4th Quartile=0.5; 95% CI: 0.2, 0.9). Secundum atrial septal defects were inversely associated with carbon monoxide (aOR4th Quartile=0.4; 95% CI: 0.2, 0.8) and PM2.5 (aOR4th Quartile=0.5; 95% CI: 0.3, 0.8). Traffic density was associated with muscular ventricular septal defects (aOR4th Quartile=3.0, 95% CI: 1.2, 7.8) and perimembranous ventricular septal defects (aOR3rd Quartile =2.4; 95% CI: 1.3, 4.6), and inversely associated with transposition of the great arteries (aOR4th Quartile=0.3; 95% CI: 0.1, 0.8). Conclusions PM10 and traffic density may contribute to the occurrence of pulmonary valve stenosis and ventricular septal defects, respectively. The results were mixed for other pollutants and had little consistency with previous studies. PMID:23772934

Ambient air pollution and traffic exposures and congenital heart defects in the San Joaquin Valley of California.

PubMed

Padula, Amy M; Tager, Ira B; Carmichael, Suzan L; Hammond, S Katharine; Yang, Wei; Lurmann, Frederick; Shaw, Gary M

2013-07-01

Congenital anomalies are a leading cause of infant morbidity and mortality. Studies suggest associations between environmental contaminants and some anomalies, although evidence is limited. We used data from the California Center of the National Birth Defects Prevention Study and the Children's Health and Air Pollution Study to estimate the odds of 27 congenital heart defects with respect to quartiles of seven ambient air pollutant and traffic exposures in California during the first 2 months of pregnancy, 1997-2006 (n = 822 cases and n = 849 controls). Particulate matter < 10 microns (PM10 ) was associated with pulmonary valve stenosis [adjusted odds ratio (aOR)Fourth Quartile  = 2.6] [95% confidence intervals (CI) 1.2, 5.7] and perimembranous ventricular septal defects (aORThird Quartile  = 2.1) [95% CI 1.1, 3.9] after adjusting for maternal race/ethnicity, education and multivitamin use. PM2.5 was associated with transposition of the great arteries (aORThird Quartile  = 2.6) [95% CI 1.1, 6.5] and inversely associated with perimembranous ventricular septal defects (aORFourth Quartile  = 0.5) [95% CI 0.2, 0.9]. Secundum atrial septal defects were inversely associated with carbon monoxide (aORFourth Quartile  = 0.4) [95% CI 0.2, 0.8] and PM2.5 (aORFourth Quartile  = 0.5) [95% CI 0.3, 0.8]. Traffic density was associated with muscular ventricular septal defects (aORFourth Quartile  = 3.0) [95% CI 1.2, 7.8] and perimembranous ventricular septal defects (aORThird Quartile  = 2.4) [95% CI 1.3, 4.6], and inversely associated with transposition of the great arteries (aORFourth Quartile  = 0.3) [95% CI 0.1, 0.8]. PM10 and traffic density may contribute to the occurrence of pulmonary valve stenosis and ventricular septal defects, respectively. The results were mixed for other pollutants and had little consistency with previous studies. © 2013 John Wiley & Sons Ltd.

Electronic structure and STM images simulation of defects on hBN/ black-phosphorene heterostructures: A theoretical study

NASA Astrophysics Data System (ADS)

Ospina, D. A.; Cisternas, E.; Duque, C. A.; Correa, J. D.

2018-03-01

By first principles calculations which include van der Waals interactions, we studied the electronic structure of hexagonal boron-nitride/black-phosphorene heterostructures (hBN/BP). In particular the role of several kind of defects on the electronic properties of black-phosphorene monolayer and hBN/BP heterostructure was analyzed. The defects under consideration were single and double vacancies, as well Stone-Wale type defects, all of them present in the phosphorene layer. In this way, we found that the electronic structure of the hBN/BP is modified according the type of defect that is introduced. As a remarkable feature, our results show occupied states at the Fermi Level introduced by a single vacancy in the energy gap of the hBN/BP heterostructure. Additionally, we performed simulations of scanning tunneling microscopy images. These simulations show that is possible to discriminate the kind of defect even when the black-phosphorene monolayer is part of the heterostructure hBN/BP. Our results may help to discriminate among several kind of defects during experimental characterization of these novel materials.

Effect of Surface and Defect Chemistry on the Photocatalytic Properties of Intentionally Defect-Rich ZnO Nanorod Arrays.

PubMed

Kegel, Jan; Zubialevich, Vitaly Z; Schmidt, Michael; Povey, Ian M; Pemble, Martyn E

2018-05-30

Due to the abundance of intrinsic defects in zinc oxide (ZnO), the material properties are often governed by same. Knowledge of the defect chemistry has proven to be highly important, especially in terms of the photocatalytic degradation of pollutants. Given the fact that defect-free materials or structures exhibiting only one type of defect are extremely difficult to produce, it is necessary to evaluate what influence various defects may have when present together in the material. In this study, intentionally defect-rich ZnO nanorod (NR) arrays are grown using a simple low-temperature solution-based growth technique. Upon changing the defect chemistry using rapid thermal annealing (RTA) the material properties are carefully assessed and correlated to the resulting photocatalytic properties. Special focus is put on the investigation of these properties for samples showing strong orange photoluminescence (PL). It is shown that intense orange emitting NR arrays exhibit improved dye-degradation rates under UV-light irradiation. Furthermore, strong dye-adsorption has been observed for some samples. This behavior is found to stem from a graphitic surface structure (e.g., shell) formed during RTA in vacuum. Since orange-luminescent samples also exhibit an enhancement of the dye adsorption a possible interplay and synergy of these two defects is elucidated. Additionally, evidence is presented suggesting that in annealed ZnO NRs structural defects may be responsible for the often observed PL emission at 3.31 eV. However, a clear correlation with the photocatalytic properties could not be established for these defects. Building on the specific findings presented here, this study also presents some more general guidelines which, it is suggested, should be employed when assessing the photocatalytic properties of defect-rich ZnO.

Emergent presentation of decompensated mitral valve prolapse and atrial septal defect.

PubMed

Kang, Jessie; Das, Bijon

2015-05-01

Mitral valve prolapse is not commonly on the list of differential diagnosis when a patient presents in the emergency department (ED) in severe distress, presenting with non-specific features such as abdominal pain, tachycardia and dyspnea. A healthy 55-year-old man without significant past medical history arrived in the ED with a unique presentation of a primary mitral valve prolapse with an atrial septal defect uncommon in cardiology literature. Early recognition of mitral valve prolapse in high-risk patients for severe mitral regurgitation or patients with underlying cardiovascular abnormalities such as an atrial septal defect is crucial to prevent morbid outcomes such as sudden cardiac death.

Maternal diet supplementation with methyl donors and increased parity affect the incidence of craniofacial defects in the offspring of twisted gastrulation mutant mice.

PubMed

Billington, Charles J; Schmidt, Brian; Zhang, Lei; Hodges, James S; Georgieff, Michael K; Schotta, Gunnar; Gopalakrishnan, Rajaram; Petryk, Anna

2013-03-01

Diets rich in methyl-donating compounds, including folate, can provide protection against neural tube defects, but their role in preventing craniofacial defects is less clear. Mice deficient in Twisted gastrulation (TWSG1), an extracellular modulator of bone morphogenetic protein signaling, manifest both midline facial defects and jaw defects, allowing study of the effects of methyl donors on various craniofacial defects in an experimentally tractable animal model. The goal of this study was to examine the effects of maternal dietary supplementation with methyl donors on the incidence and type of craniofacial defects among Twsg1(-/-) offspring. Nulliparous and primiparous female mice were fed an NIH31 standard diet (control) or a methyl donor supplemented (MDS) diet (folate, vitamin B-12, betaine, and choline). Observed defects in the pups were divided into those derived mostly from the first branchial arch (BA1) (micrognathia, agnathia, cleft palate) and midline facial defects in the holoprosencephaly spectrum (cyclopia, proboscis, and anterior truncation). In the first pregnancy, offspring of mice fed the MDS diet had lower incidence of BA1-derived defects (12.8% in MDS vs. 32.5% in control; P = 0.02) but similar incidence of midline facial defects (6.4% in MDS vs. 5.2% in control; P = 1.0). Increased maternal parity was independently associated with increased incidence of craniofacial defects after adjusting for diet (from 37.7 to 59.5% in control, P = 0.04 and from 19.1 to 45.3% in MDS, P = 0.045). In conclusion, methyl donor supplementation shows protective effects against jaw defects, but not midline facial defects, and increased parity can be a risk factor for some craniofacial defects.

Betaine supplementation reduces congenital defects after prenatal alcohol exposure (Conference Presentation)

NASA Astrophysics Data System (ADS)

Karunamuni, Ganga; Gu, Shi; Doughman, Yong Qiu; Sheehan, Megan M.; Ma, Pei; Peterson, Lindsy M.; Linask, Kersti K.; Jenkins, Michael W.; Rollins, Andrew M.; Watanabe, Michiko

2016-03-01

Over 500,000 women per year in the United States drink during pregnancy, and 1 in 5 of this population also binge drink. As high as 20-50% of live-born children with prenatal alcohol exposure (PAE) present with congenital heart defects including outflow and valvuloseptal anomalies that can be life-threatening. Previously we established a model of PAE (modeling a single binge drinking episode) in the avian embryo and used optical coherence tomography (OCT) imaging to assay early-stage cardiac function/structure and late-stage cardiac defects. At early stages, alcohol/ethanol-exposed embryos had smaller cardiac cushions and increased retrograde flow. At late stages, they presented with gross morphological defects in the head and chest wall, and also exhibited smaller or abnormal atrio-ventricular (AV) valves, thinner interventricular septae (IVS), and smaller vessel diameters for the aortic trunk branches. In other animal models, the methyl donor betaine (found naturally in many foods such as wheat bran, quinoa, beets and spinach) ameliorates neurobehavioral deficits associated with PAE but the effects on heart structure are unknown. In our model of PAE, betaine supplementation led to a reduction in gross structural defects and appeared to protect against certain types of cardiac defects such as ventricular septal defects and abnormal AV valvular morphology. Furthermore, vessel diameters, IVS thicknesses and mural AV leaflet volumes were normalized while the septal AV leaflet volume was increased. These findings highlight the importance of betaine and potentially methylation levels in the prevention of PAE-related birth defects which could have significant implications for public health.

Agricultural Compounds in Water and Birth Defects.

PubMed

Brender, Jean D; Weyer, Peter J

2016-06-01

Agricultural compounds have been detected in drinking water, some of which are teratogens in animal models. The most commonly detected agricultural compounds in drinking water include nitrate, atrazine, and desethylatrazine. Arsenic can also be an agricultural contaminant, although arsenic often originates from geologic sources. Nitrate has been the most studied agricultural compound in relation to prenatal exposure and birth defects. In several case-control studies published since 2000, women giving birth to babies with neural tube defects, oral clefts, and limb deficiencies were more likely than control mothers to be exposed to higher concentrations of drinking water nitrate during pregnancy. Higher concentrations of atrazine in drinking water have been associated with abdominal defects, gastroschisis, and other defects. Elevated arsenic in drinking water has also been associated with birth defects. Since these compounds often occur as mixtures, it is suggested that future research focus on the impact of mixtures, such as nitrate and atrazine, on birth defects.

Characterization of point defects in monolayer arsenene

NASA Astrophysics Data System (ADS)

Liang, Xiongyi; Ng, Siu-Pang; Ding, Ning; Wu, Chi-Man Lawrence

2018-06-01

Topological defects that are inevitably found in 2D materials can dramatically affect their properties. Using density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) method, the structural, thermodynamic, electronic and magnetic properties of six types of typical point defects in arsenene, i.e. the Stone-Wales defect, single and double vacancies and adatoms, were systemically studied. It was found that these defects were all more easily generated in arsenene with lower formation energies than those with graphene and silicene. Stone-Wales defects can be transformed from pristine arsenene by overcoming a barrier of 2.19 eV and single vacancy defects tend to coalesce into double vacancy defects by diffusion. However, a type of adatom defect does not exhibit kinetic stability at room temperature. In addition, SV defects and another type of adatom defect can remarkably affect the electronic and magnetic properties of arsenene, e.g. they can introduce localized states near the Fermi level, as well as a strongly local magnetic moment due to dangling bond and unpaired electron. Furthermore, the simulated scanning tunneling microscopy (STM) and Raman spectroscopy were computed and the types of point defects can be fully characterized by correlating the STM images and Raman spectra to the defective atomistic structures. The results provide significant insights to the effect of defects in arsenene for potential applications, as well as identifications of two helpful tools (STM and Raman spectroscopy) to distinguish the type of defects in arsenene for future experiments.

Electronic characterization of defects in narrow gap semiconductors

NASA Technical Reports Server (NTRS)

Patterson, James D.

1993-01-01

The study of point defects in semiconductors has a long and honorable history. In particular, the detailed understanding of shallow defects in common semiconductors traces back to the classic work of Kohn and Luttinger. However, the study of defects in narrow gap semiconductors represents a much less clear story. Here, both shallow defects (caused by long range potentials) and deep defects (from short range potentials) are far from being completely understood. In this study, all results are calculational and our focus is on the chemical trend of deep levels in narrow gap semiconductors. We study substitutional (including antisite), interstitial and ideal vacancy defects. For substitutional and interstitial impurities, the efects of relaxation are included. For materials like Hg(1-x)Cd(x)Te, we study how the deep levels vary with x, of particular interest is what substitutional and interstitial atoms yield energy levels in the gap i.e. actually produce deep ionized levels. Also, since the main technique utilized is Green's functions, we include some summary of that method.

Native point defects in GaSb

NASA Astrophysics Data System (ADS)

Kujala, J.; Segercrantz, N.; Tuomisto, F.; Slotte, J.

2014-10-01

We have applied positron annihilation spectroscopy to study native point defects in Te-doped n-type and nominally undoped p-type GaSb single crystals. The results show that the dominant vacancy defect trapping positrons in bulk GaSb is the gallium monovacancy. The temperature dependence of the average positron lifetime in both p- and n-type GaSb indicates that negative ion type defects with no associated open volume compete with the Ga vacancies. Based on comparison with theoretical predictions, these negative ions are identified as Ga antisites. The concentrations of these negatively charged defects exceed the Ga vacancy concentrations nearly by an order of magnitude. We conclude that the Ga antisite is the native defect responsible for p-type conductivity in GaSb single crystals.

Promoting the Adsorption of Metal Ions on Kaolinite by Defect Sites: A Molecular Dynamics Study

PubMed Central

Li, Xiong; Li, Hang; Yang, Gang

2015-01-01

Defect sites exist abundantly in minerals and play a crucial role for a variety of important processes. Here molecular dynamics simulations are used to comprehensively investigate the adsorption behaviors, stabilities and mechanisms of metal ions on defective minerals, considering different ionic concentrations, defect sizes and contents. Outer-sphere adsorbed Pb2+ ions predominate for all models (regular and defective), while inner-sphere Na+ ions, which exist sporadically only at concentrated solutions for regular models, govern the adsorption for all defective models. Adsorption quantities and stabilities of metal ions on kaolinite are fundamentally promoted by defect sites, thus explaining the experimental observations. Defect sites improve the stabilities of both inner- and outer-sphere adsorption, and (quasi) inner-sphere Pb2+ ions emerge only at defect sites that reinforce the interactions. Adsorption configurations are greatly altered by defect sites but respond weakly by changing defect sizes or contents. Both adsorption quantities and stabilities are enhanced by increasing defect sizes or contents, while ionic concentrations mainly affect adsorption quantities. We also find that adsorption of metal ions and anions can be promoted by each other and proceeds in a collaborative mechanism. Results thus obtained are beneficial to comprehend related processes for all types of minerals. PMID:26403873

The Development of Spectroscopic Techniques to Study Defects in Thin Film Silicon-Dioxide

NASA Astrophysics Data System (ADS)

Zvanut, Mary Ellen

This dissertation research concerns the study of defects in thin film sputtered SiO_2 which is used as an optical coating material. The capacitance-voltage and current-voltage techniques typically used in microelectronics investigations were used to examine the concentration, location, and kinetics of charge in an aluminum-sputtered oxide-native oxide-silicon capacitor. The response of the capacitor to low field bias stress reveals a hysteretic trapping behavior similar to that observed in microelectronic grade oxide films. In an effort to understand this phenomenon, a band-to-trap tunneling model was developed based on the assumption that the defect involved exhibits a delta function spatial distribution and an extended energy distribution. The central feature of this model, defect relaxation, provides a physical explanation for the hysteretic trapping behavior. Analysis yields that the trap is located spatially within 2 nm of the Si/SiO _2 interface and energetically less than 5 eV from the SiO_2 conduction band edge. The relaxation energy associated with the capture of an electron at the trap is 0.1-2.2 eV. Correlation of the electrical measurements executed for this investigation with electron paramagnetic resonance (EPR) data obtained by Dr. P. Caplan provides structural information about the defect involved with the hysteretic trapping phenomenon. EPR results obtained before and after subjecting an oxide-silicon structure to corona discharge suggest that the trapping center is an E^ ' defect. The technique of band-to-trap tunneling spectroscopy combined with the EPR experiments provides the first reported trap depth associated with the capture of a hole at an E^' center located near the silicon surface of an oxide/silicon system.

Topological Transformation of Defects in Nematic Liquid Crystals

NASA Astrophysics Data System (ADS)

Pagel, Zachary; Atherton, Timothy; Guasto, Jeffrey; Cebe, Peggy

A topological transformation around silica microsphere inclusions in nematic liquid crystal cells (LCC) is experimentally studied. Silica microspheres are coated to induce homeotropic LC anchoring to the spheres. Parallel rub directions of the alignment polymer during LCC construction create a splay wall that traps the microspheres. Application of an out-of-plane electric field then permits a transformation of hedgehog defects, reversing the orientation of the defect around microspheres. The transformation controllably reverses the microsphere's direction of travel during AC electrophoresis due to defect-dependent velocity anisotropy. A similar transformation is studied on chains of microspheres with hedgehog defects, where the defect orientation is reversed on the entire chain. Polarized and confocal microscopies are used to study the defect structures. Results contribute to recent developments in microsphere electrokinetics in nematic LCs, as the transformation adds an additional degree of control in the electrophoretic motion of microspheres and chains of microspheres with dipolar defects. The author thanks NSF Grant DMR-1608126 for funding reseearch and Tufts University for funding travel.

Single Ventricle Defects

MedlinePlus

... Your Risk • Symptoms & Diagnosis • Care & Treatment • Tools & Resources Web Booklets on Congenital Heart Defects These online publications ... to you or your child’s defect and concerns. Web Booklet: Adults With Congenital Heart Defects Web Booklet: ...

Supplement use and other characteristics among pregnant women with a previous pregnancy affected by a neural tube defect - United States, 1997-2009.

PubMed

Arth, Annelise; Tinker, Sarah; Moore, Cynthia; Canfield, Mark; Agopian, Aj; Reefhuis, Jennita

2015-01-16

Neural tube defects (NTDs) include anomalies of the brain (anencephaly and encephalocele) and spine (spina bifida). Even with ongoing mandatory folic acid fortification of enriched cereal grain products, the U.S. Preventive Services Task Force recommends that women of childbearing potential consume a daily supplement containing 400 µg-800 µg of folic acid. Women with a prior NTD-affected pregnancy have an increased risk for having another NTD-affected pregnancy, and if they are planning another pregnancy, the recommendation is that they consume high-dosage folic acid supplements (4.0 mg/day) beginning ≥4 weeks before conception and continuing through the first 12 weeks of pregnancy. To learn whether folic acid supplementation (from multivitamins or single- ingredient supplements) was commonly used during pregnancy by women with a previous NTD-affected pregnancy, supplement use was assessed among a convenience sample of women with a previous NTD-affected pregnancy who participated in the National Birth Defects Prevention Study (NBDPS), a case-control study of major birth defects in the United States. Characteristics of women who previously had an NTD-affected pregnancy and whose index pregnancy (pregnancy included in NBDPS) was either affected by an NTD (N = 17) (i.e., recurrence-cases) or resulted in a live-born infant without a major birth defect (N = 10) (i.e., recurrence-controls) were assessed. Taking a supplement that included folic acid was more common among recurrence-control mothers (80%) than recurrence-case mothers (35%). The recommendation that women should take folic acid supplements just before and during early pregnancy is not being followed by many women and offers an opportunity for NTD prevention, especially among women who are at a higher risk because they have had a previous pregnancy affected by an NTD.

A study of vacancy defects related to gray tracks in KTiOPO{sub 4} (KTP) using positron annihilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yang; Li, Jing; Wang, Jiyang, E-mail: hdjiang@sdu.edu.cn

For the first time to our knowledge, positron annihilation spectroscopy (PAS) was used to study vacancy defects in KTiOPO{sub 4} (KTP) single crystals. Positron annihilation lifetime spectroscopy combined with dielectric measurements identified the existence of oxygen vacancies and reflected the concentration of vacancy defects in three samples. The vacancy defects in KTP do not consist of monovacancies, but rather vacancy complexes. Doppler broadening indicates that the vacancy defects are distributed uniformly. A relationship is established where a crystal with a low oxygen vacancy concentration and a highly balanced stoichiometry has a higher resistance to gray track formation.

Wound healing of osteotomy defects prepared with piezo or conventional surgical instruments: a pilot study in rabbits.

PubMed

Ma, Li; Mattheos, Nikos; Sun, Yan; Liu, Xi Ling; Yip Chui, Ying; Lang, Niklaus Peter

2015-08-01

The aim of the present study was to evaluate and compare the wound-healing process following osteotomies performed with either conventional rotary burs or piezoelectric surgery in a rabbit model. Two types of osteotomy window defects of the nasal cavities were prepared on the nasal bone of 16 adult New Zealand white rabbits with either a conventional rotary bur or piezo surgery. The defects were covered with a resorbable membrane. Four animals were killed at 1, 2, 3, and 5 weeks after the surgical procedure, respectively. Histological and morphometric evaluations were performed to assess the volumetric density of various tissue components: the blood clot, vascularized structures, provisional matrix, osteoid, mineralized bone, bone debris, residual tissue, and old bone. Significantly more bone debris was found at 1 week in the conventionally-prepared defects compared to the piezo surgically-prepared defects. At 2 and 3 weeks, a newly-formed hard tissue bridge, mainly composed of woven bone, was seen; however, no statistically-significant differences were observed. At 5 weeks, the defects were completely filled with newly-formed bone. The defects prepared by piezo surgery showed a significantly decreased proportion of bone debris at 1 week, compared to conventional rotary bur defect. © 2014 Wiley Publishing Asia Pty Ltd.

Defect dynamics in active nematics

PubMed Central

Giomi, Luca; Bowick, Mark J; Mishra, Prashant; Sknepnek, Rastko; Cristina Marchetti, M

2014-01-01

Topological defects are distinctive signatures of liquid crystals. They profoundly affect the viscoelastic behaviour of the fluid by constraining the orientational structure in a way that inevitably requires global changes not achievable with any set of local deformations. In active nematic liquid crystals, topological defects not only dictate the global structure of the director, but also act as local sources of motion, behaving as self-propelled particles. In this article, we present a detailed analytical and numerical study of the mechanics of topological defects in active nematic liquid crystals. PMID:25332389

Defect inspection and printability study for 14 nm node and beyond photomask

NASA Astrophysics Data System (ADS)

Seki, Kazunori; Yonetani, Masashi; Badger, Karen; Dechene, Dan J.; Akima, Shinji

2016-10-01

Two different mask inspection techniques are developed and compared for 14 nm node and beyond photomasks, High resolution and Litho-based inspection. High resolution inspection is the general inspection method in which a 19x nm wavelength laser is used with the High NA inspection optics. Litho-based inspection is a new inspection technology. This inspection uses the wafer lithography information, and as such, this method has automatic defect classification capability which is based on wafer printability. Both High resolution and Litho-based inspection methods are compared using 14 nm and 7 nm node programmed defect and production design masks. The defect sensitivity and mask inspectability is compared, in addition to comparing the defect classification and throughput. Additionally, the Cost / Infrastructure comparison is analyzed and the impact of each inspection method is discussed.

Hypoxia induced DNA damage in children with isolated septal defect and septal defect with great vessel anomaly of heart.

PubMed

G, Vidya; H Y, Suma; Bhat B, Vishnu; Chand, Parkash; Rao K, Ramachandra

2014-04-01

In Congenital Heart Disease (CHD), shunting of blood occurs through the anatomical defects which lead to mixing of oxygenated and deoxygenated blood. Chronic hypoxia which occurs due to the above said mechanism has the potency to cause DNA damage in children with CHD. In chronic hypoxia, there is a liberation of Reactive Oxygen Species (ROS) due to tissue injury as a result of ischemia and induction of hypoxia inducible factor - 1HIF-1 and p53 which in turn activates pro-apoptotic factors leading to alteration in the regulation of pro-apoptotic gene Blc-2 to be involved in causing the DNA damage. The extent of chronic hypoxia and the DNA damage depends on the nature of the anatomical heart defect. Hence, the present case-control study was conducted to find out the DNA damage in children with isolated septal defect and septal defect with great vessel anomaly of heart and to compare the same. The study group was categorized into those with isolated septal defects and septal defects associated with great vessel anomaly based on echo-cardiogram. Age and sex matched healthy children were taken as controls. Single-cell gel electrophoresis - Comet Assay of Alkaline Version was performed conventionally and the comets were analyzed using comet score software. The comet metrics was found to be statistically significant in children with isolated septal defect and septal defect with great vessel anomaly when compared with that of the controls. In addition, comet metrics also showed significantly increased DNA damage among children with septal defects associated with great vessel anomaly when compared to isolated septal defects. The data strongly suggests a linear correlation of severity of the anomaly involved with the degree of DNA damage as evidenced by lesser extent of DNA damage in isolated septal defect and greater in septal defect with great vessel anomaly.

Polydispersity-driven topological defects as order-restoring excitations.

PubMed

Yao, Zhenwei; Olvera de la Cruz, Monica

2014-04-08

The engineering of defects in crystalline matter has been extensively exploited to modify the mechanical and electrical properties of many materials. Recent experiments on manipulating extended defects in graphene, for example, show that defects direct the flow of electric charges. The fascinating possibilities offered by defects in two dimensions, known as topological defects, to control material properties provide great motivation to perform fundamental investigations to uncover their role in various systems. Previous studies mostly focus on topological defects in 2D crystals on curved surfaces. On flat geometries, topological defects can be introduced via density inhomogeneities. We investigate here topological defects due to size polydispersity on flat surfaces. Size polydispersity is usually an inevitable feature of a large variety of systems. In this work, simulations show well-organized induced topological defects around an impurity particle of a wrong size. These patterns are not found in systems of identical particles. Our work demonstrates that in polydispersed systems topological defects play the role of restoring order. The simulations show a perfect hexagonal lattice beyond a small defective region around the impurity particle. Elasticity theory has demonstrated an analogy between the elementary topological defects named disclinations to electric charges by associating a charge to a disclination, whose sign depends on the number of its nearest neighbors. Size polydispersity is shown numerically here to be an essential ingredient to understand short-range attractions between like-charge disclinations. Our study suggests that size polydispersity has a promising potential to engineer defects in various systems including nanoparticles and colloidal crystals.

Resist process optimization for further defect reduction

NASA Astrophysics Data System (ADS)

Tanaka, Keiichi; Iseki, Tomohiro; Marumoto, Hiroshi; Takayanagi, Koji; Yoshida, Yuichi; Uemura, Ryouichi; Yoshihara, Kosuke

2012-03-01

Defect reduction has become one of the most important technical challenges in device mass-production. Knowing that resist processing on a clean track strongly impacts defect formation in many cases, we have been trying to improve the track process to enhance customer yield. For example, residual type defect and pattern collapse are strongly related to process parameters in developer, and we have reported new develop and rinse methods in the previous papers. Also, we have reported the optimization method of filtration condition to reduce bridge type defects, which are mainly caused by foreign substances such as gels in resist. Even though we have contributed resist caused defect reduction in past studies, defect reduction requirements continue to be very important. In this paper, we will introduce further process improvements in terms of resist defect reduction, including the latest experimental data.

Academic Outcomes in Children With Congenital Heart Defects: A Population-Based Cohort Study.

PubMed

Oster, Matthew E; Watkins, Stephanie; Hill, Kevin D; Knight, Jessica H; Meyer, Robert E

2017-02-01

Most studies evaluating neurocognitive outcomes in children with congenital heart defects (CHD) have focused on high-risk patients or used specialized, resource-intensive testing. To determine the association of CHD with academic outcomes and compare outcomes according to the severity of CHD, we linked state educational records with a birth defects registry and birth certificates. We performed a retrospective cohort study using data from the North Carolina Birth Defects Monitoring Program, North Carolina Department of Public Instruction, and North Carolina Department of Health and Human Services vital records. We performed logistic regression, adjusting for maternal education, race/ethnicity, enrollment in public pre-Kindergarten, and gestational age, to determine the association of CHD with not meeting standards on reading and math end-of-grade examinations in third grade in 2006 to 2012. Of 5624 subjects with CHD and 10 832 with no structural birth defects, 2807 (50%) and 6355 (59%) were linked, respectively. Children with CHD had 1.24× the odds of not meeting standards in either reading or math (95% confidence interval, 1.12-1.37), with 44.6% of children with CHD not meeting standards in at least one of these areas compared with 37.5% without CHD. Although children with both critical and noncritical CHD had poorer outcomes, those with critical CHD were significantly more likely to receive exceptional services compared with the noncritical group (adjusted odds ratio, 1.46; 95% confidence interval, 1.15-1.86). Children with all types of CHD have poorer academic outcomes compared with their peers. Evaluation for exceptional services should be considered in children with any type of CHD. © 2017 American Heart Association, Inc.

[Inconformity between soft tissue defect and bony defect in incomplete cleft palate].

PubMed

Zhou, Xia; Ma, Lian

2014-12-01

To evaluate the inconformity between soft tissue defect and bony defect by observing the cleft extent of palate with complete secondary palate bony cleft in incomplete cleft palate patient. The patients with incomplete cleft palate treated in Hospital of Stomatology Peking University from July 2012 to June 2013 were reviewed, of which 75 cases with complete secondary palate bony cleft were selected in this study. The CT scan and intraoral photograph were taken before operation. The patients were classified as four types according to the extent of soft tissue defect. Type 1: soft tissue defect reached incisive foremen region, Type 2 was hard and soft cleft palate, Type 3 soft cleft palate and Type 4 submucous cleft palate. Type 1 was defined as conformity group (CG). The other three types were defined as inconformity group (ICG) and divided into three subgroups (ICG-I), (ICG-II) and (ICG-III). Fifty-seven patients were in ICG group, and the rate of inconformity was 76% (57/75). The percentage of ICG-I, ICG-II and ICG-III was 47% (27/57), 23% (13/57) and 30% (17/57), respevtively. There are different types of soft tissue deformity with complete secondary palate bony cleft. The inconformity between soft tissue and hard tissue defect exits in 3/4 of isolated cleft palate patients.

Box 6: Nanoscale Defects

NASA Astrophysics Data System (ADS)

Alves, Eduardo; Breese, Mark

Defects affect virtually all properties of crystalline materials, and their role is magnified in nanoscale structures. In this box we describe the different type of defects with particular emphasis on point and linear defects. Above zero Kelvin all real materials have a defect population within their structure, which affects either their crystalline, electronic or optical properties. It is common to attribute a negative connotation to the presence of defects. However, a perfect silicon crystal or any other defect-free semiconductor would have a limited functionality and might even be useless.

Native point defects in GaSb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kujala, J.; Segercrantz, N.; Tuomisto, F.

2014-10-14

We have applied positron annihilation spectroscopy to study native point defects in Te-doped n-type and nominally undoped p-type GaSb single crystals. The results show that the dominant vacancy defect trapping positrons in bulk GaSb is the gallium monovacancy. The temperature dependence of the average positron lifetime in both p- and n-type GaSb indicates that negative ion type defects with no associated open volume compete with the Ga vacancies. Based on comparison with theoretical predictions, these negative ions are identified as Ga antisites. The concentrations of these negatively charged defects exceed the Ga vacancy concentrations nearly by an order of magnitude.more » We conclude that the Ga antisite is the native defect responsible for p-type conductivity in GaSb single crystals.« less

Risk factors for neural tube defects in Riyadh City, Saudi Arabia: Case-control study.

PubMed

Salih, Mustafa A M; Murshid, Waleed R; Mohamed, Ashry Gad; Ignacio, Lena C; de Jesus, Julie E; Baabbad, Rubana; El Bushra, Hassan M

2014-01-01

Both genetic and non-genetic environmental factors are involved in the etiology of neural tube defects (NTD) which affect 0.5-2/1000 pregnancies worldwide. This study aimed to explore the risk factors for the development of NTD in Saudi population, and highlight identifiable and preventable causes. Similar studies are scarce in similar populations ofthe Arabian Peninsula and North Africa. This is an unmatched concurrent case-control study including NTD cases born at King Khalid University Hospital, Riyadh during a 4-year period (2002-2006). The case-control study included 25 cases and 125 controls (case: control ratio of 1:5). Years of formal education, employment, household environment (including availability of air conditioning) and rate of parental consanguinity did not differ between mothers of cases and controls. Significantly higher proportion of mothers of cases had history of stillbirth compared to control mothers (16% vs 4.1%, P=0.02). Also family history of hydrocephalus and congenital anomalies were more prevalent in cases than controls (P values=0.0000 and 0.003, respectively). There was significant protective effect of periconceptional folic acid consumption both prior to conception (OR 0.02, 95% CI 0.00-0.07) and during the first 6 weeks of conception (OR 0.13, 95% CI 0.04-0.39). Further research, including a larger cohort, is required to enable ascertainment of gene-nutrient and gene environment interactions associated with NTD in Saudi Arabia.

Large-size TlBr single crystal growth and defect study

NASA Astrophysics Data System (ADS)

Zhang, Mingzhi; Zheng, Zhiping; Chen, Zheng; Zhang, Sen; Luo, Wei; Fu, Qiuyun

2018-04-01

Thallium bromide (TlBr) is an attractive semiconductor material for fabrication of radiation detectors due to its high photon stopping power originating from its high atomic number, wide band gap and high resistivity. In this paper the vertical Bridgman method was used for crystal growth and TlBr single crystals with diameter of 15 mm were grown. X-ray diffraction (XRD) was used to identify phase and orientation. Electron backscatter diffraction (EBSD) was used to investigate crystal microstructure and crystallographic orientation. The optical and electric performance of the crystal was characterized by infrared (IR) transmittance spectra and I-V measurement. The types of point defects in the crystals were investigated by thermally stimulated current (TSC) spectra and positron annihilation spectroscopy (PAS). Four types of defects, with ionization energy of each defect fitting as follows: 0.1308, 0.1540, 0.3822 and 0.538 eV, were confirmed from the TSC result. The PAS result showed that there were Tl vacancies in the crystal.

Nonlinear defect localized modes and composite gray and anti-gray solitons in one-dimensional waveguide arrays with dual-flip defects

NASA Astrophysics Data System (ADS)

Liu, Yan; Guan, Yefeng; Li, Hai; Luo, Zhihuan; Mai, Zhijie

2017-08-01

We study families of stationary nonlinear localized modes and composite gray and anti-gray solitons in a one-dimensional linear waveguide array with dual phase-flip nonlinear point defects. Unstaggered fundamental and dipole bright modes are studied when the defect nonlinearity is self-focusing. For the fundamental modes, symmetric and asymmetric nonlinear modes are found. Their stable areas are studied using different defect coefficients and their total power. For the nonlinear dipole modes, the stability conditions of this type of mode are also identified by different defect coefficients and the total power. When the defect nonlinearity is replaced by the self-defocusing one, staggered fundamental and dipole bright modes are created. Finally, if we replace the linear waveguide with a full nonlinear waveguide, a new type of gray and anti-gray solitons, which are constructed by a kink and anti-kink pair, can be supported by such dual phase-flip defects. In contrast to the usual gray and anti-gray solitons formed by a single kink, their backgrounds on either side of the gray hole or bright hump have the same phase.

Temporal and Spatial Analysis of Neural Tube Defects and Detection of Geographical Factors in Shanxi Province, China

PubMed Central

He, Lei; Wang, Jinfeng; Liu, Xin; Zhang, Ningxu; Xu, Bing

2016-01-01

Background Neural tube defects (NTDs) are congenital birth defects that occur in the central nervous system, and they have the highest incidence among all birth defects. Shanxi Province in China has the world’s highest rate of NTDs. Since the 1990s, China’s government has worked on many birth defect prevention programs to reduce the occurrence of NTDs, such as pregnancy planning, health education, genetic counseling, antenatal ultrasonography and serological screening. However, the rate of NTDs in Shanxi Province is still higher than the world’s average morbidity rate after intervention. In addition, Shanxi Province has abundant coal reserves, and is the largest coal production province in China. The objectives of this study are to determine the temporal and spatial variation of the NTD rate in rural areas of Shanxi Province, China, and identify geographical environmental factors that were associated with NTDs in the risk area. Methods In this study, Heshun County and Yuanping County in Shanxi Province, which have high incidence of NTDs, were selected as the study areas. Two paired sample T test was used to analyze the changes in the risk of NTDs from the time dimension. Ripley’s k function and spatial filtering were combined with geographic information system (GIS) software to study the changes in the risk of NTDs from the spatial dimension. In addition, geographical detectors were used to identify the risk geographical environmental factors of NTDs in the study areas, especially the areas close to the coal sites and main roads. Results In both Heshun County and Yuanping County, the incidence of NTDs was significantly (P<0.05) reduced after intervention. The results from spatial analysis showed that significant spatial heterogeneity existed in both counties. NTD clusters were still identified in areas close to coal sites and main roads after interventions. This study also revealed that the elevation, fault and soil types always had a larger influence on

Study of critical defects in ablative heat shield systems for the space shuttle

NASA Technical Reports Server (NTRS)

Miller, C. C.; Rummel, W. D.

1974-01-01

Experimental results are presented for a program conducted to determine the effects of fabrication-induced defects on the performance of an ablative heat shield material. Exposures representing a variety of space shuttle orbiter mission environments-humidity acoustics, hot vacuum and cold vacuum-culuminating in entry heating and transonic acoustics, were simulated on large panels containing intentional defects. Nondestructive methods for detecting the defects, were investigated. The baseline materials were two honeycomb-reinforced low density, silicone ablators, MG-36 and SS-41. Principal manufacturing-induced defects displaying a critical potential included: off-curing of the ablator, extreme low density, undercut (or crushed) honeycomb reinforcements, and poor wet-coating of honeycomb.

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

Digital volume tomography in the diagnosis of peri-implant defects: an in vitro study on native pig mandibles.

PubMed

Mengel, Reiner; Kruse, Björn; Flores-de-Jacoby, Lavin

2006-07-01

The aim of this study of native pig mandibles was to investigate the accuracy and quality of the representation of peri-implant defects by intraoral radiography (IR), panoramic radiography (PR), computer tomography (CT), and digital volume tomography (DVT). The examination was carried out on 19 native pig mandibles. In the toothless sections of the mandibles, one or two implants were inserted. Following the standardized preparation of peri-implant defects (11 each of dehiscences, fenestrations, and 2- to 3-walled intrabony defects), IR, PR, CT, and DVT were performed. The peri-implant defects were measured using appropriate software on the digitized IR and PR image programs. As a control method, the peri-implant bone defects were measured directly using a reflecting stereomicroscope with measuring ocular. The statistical comparison between the measurements of the radiographic scans and those of the direct readings of the peri-implant defects was performed with Pearson's correlation coefficient. The quality of the radiographic scans was determined through the subjective perception and detectability of the peri-implant defects by five independent observers. In the DVT and CT scans, it was possible to measure all the bone defects in three planes. Comparison with the direct peri-implant defect measurements yielded a mean deviation of 0.17+/-0.11 mm for the DVT scans and 0.18+/-0.12 mm for the CT scans. On the IR and PR images, the defects could be detected only in the mesio-distal and cranio-caudal planes. In comparison with the direct measurements of the peri-implant defects, the IR images revealed a mean deviation of 0.34+/-0.30 mm, and the PR images revealed a mean deviation of 0.41+/-0.35 mm. The quality rating of the radiographic images was highest for the DVT scans. Overall, the CT and DVT scans displayed only a slight deviation in the extent of the peri-implant defects. Both radiographic imaging techniques permitted imaging of peri-implant defects in three

The Detection of Burn-Through Weld Defects Using Noncontact Ultrasonics

PubMed Central

Abbasi, Zeynab; Yuhas, Donald; Zhang, Lu; Basantes, Alexandra-Del-Carmen; Tehrani, Niloofar Nabili; Ozevin, Didem; Indacochea, Ernesto

2018-01-01

Nearly all manufactured products in the metal industry involve welding. The detection and correction of defects during welding improve the product reliability and quality, and prevent unexpected failures. Nonintrusive process control is critical for avoiding these defects. This paper investigates the detection of burn-through damage using noncontact, air-coupled ultrasonics, which can be adapted to the immediate and in-situ inspection of welded samples. The burn-through leads to a larger volume of degraded weld zone, providing a resistance path for the wave to travel which results in lower velocity, energy ratio, and amplitude. Wave energy dispersion occurs due to the increase of weld burn-through resulting in higher wave attenuation. Weld sample micrographs are used to validate the ultrasonic results. PMID:29342875

Multiscale simulations of defect dipole-enhanced electromechanical coupling at dilute defect concentrations

NASA Astrophysics Data System (ADS)

Liu, Shi; Cohen, R. E.

2017-08-01

The role of defects in solids of mixed ionic-covalent bonds such as ferroelectric oxides is complex. Current understanding of defects on ferroelectric properties at the single-defect level remains mostly at the empirical level, and the detailed atomistic mechanisms for many defect-mediated polarization-switching processes have not been convincingly revealed quantum mechanically. We simulate the polarization-electric field (P-E) and strain-electric field (ɛ-E) hysteresis loops for BaTiO3 in the presence of generic defect dipoles with large-scale molecular dynamics and provide a detailed atomistic picture of the defect dipole-enhanced electromechanical coupling. We develop a general first-principles-based atomistic model, enabling a quantitative understanding of the relationship between macroscopic ferroelectric properties and dipolar impurities of different orientations, concentrations, and dipole moments. We find that the collective orientation of dipolar defects relative to the external field is the key microscopic structure feature that strongly affects materials hardening/softening and electromechanical coupling. We show that a small concentration (≈0.1 at. %) of defect dipoles dramatically improves electromechanical responses. This offers the opportunity to improve the performance of inexpensive polycrystalline ferroelectric ceramics through defect dipole engineering for a range of applications including piezoelectric sensors, actuators, and transducers.

Effects of LED phototherapy on bone defects grafted with MTA, bone morphogenetic proteins and guided bone regeneration: a Raman spectroscopic study.

PubMed

Pinheiro, Antonio L B; Soares, Luiz G P; Cangussú, Maria Cristina T; Santos, Nicole R S; Barbosa, Artur Felipe S; Silveira Júnior, Landulfo

2012-09-01

We studied peaks of calcium hydroxyapatite (CHA) and protein and lipid CH groups in defects grafted with mineral trioxide aggregate (MTA) treated or not with LED irradiation, bone morphogenetic proteins and guided bone regeneration. A total of 90 rats were divided into ten groups each of which was subdivided into three subgroups (evaluated at 15, 21 and 30 days after surgery). Defects were irradiated with LED light (wavelength 850 ± 10 nm) at 48-h intervals for 15 days. Raman readings were taken at the surface of the defects. There were no statistically significant differences in the CHA peaks among the nonirradiated defects at any of the experimental time-points. On the other hand, there were significant differences between the defects filled with blood clot and the irradiated defects at all time-points (p < 0.001, p = 0.02, p < 0.001). There were significant differences between the mean peak CHA in nonirradiated defects at all the experimental time-points (p < 0.01). The mean peak of the defects filled with blood clot was significantly different from that of the defects filled with MTA (p < 0.001). There were significant differences between the defects filled with blood clot and the irradiated defects (p < 0.001). The results of this study using Raman spectral analysis indicate that infrared LED light irradiation improves the deposition of CHA in healing bone grafted or not with MTA.

Density functional studies of the defect-induced electronic structure modifications in bilayer boronitrene

NASA Astrophysics Data System (ADS)

Ukpong, A. M.; Chetty, N.

2012-05-01

The van der Waals interaction-corrected density functional theory is used in this study to investigate the formation, energetic stability, and inter-layer cohesion in bilayer hexagonal boronitrene. The effect of inter-layer separation on the electronic structure is systematically investigated. The formation and energetic stability of intrinsic defects are also investigated at the equilibrium inter-layer separation. It is found that nonstoichiometric defects, and their complexes, that induce excess nitrogen or excess boron, in each case, are relatively more stable in the atmosphere that corresponds to the excess atomic species. The modifications of the electronic structure due to formation of complexes are also investigated. It is shown that van der Waals density functional theory gives an improved description of the cohesive properties but not the electronic structure in bilayer boronitrene compared to other functionals. We identify energetically favourable topological defects that retain the energy gap in the electronic structure, and discuss their implications for band gap engineering in low-n layer boronitrene insulators. The relative strengths and weaknesses of the functionals in predicting the properties of bilayer boronitrene are also discussed.

Back-irradiation photonic sintering for defect-free high-conductivity metal patterns on transparent plastic

NASA Astrophysics Data System (ADS)

Kwak, Ji Hye; Chun, Su Jin; Shon, Chae-Hwa; Jung, Sunshin

2018-04-01

Photonic sintering has attracted considerable attention for printed electronics. It irradiates high-intensity light onto the front surface of metal nanoparticle patterns, which often causes defects such as delamination, cavities, and cracks in the patterns. Here, a back-irradiation photonic sintering method is developed for obtaining defect-free high-conductivity metal patterns on a transparent plastic substrate, through which high-intensity light is irradiated onto the back surface of the patterns for a few milliseconds. Ag patterns back-irradiated with ˜10.0 J cm-2 are defect-free in contrast to front-irradiated patterns and exhibited an electrical conductivity of ˜2.3 × 107 S m-1. Furthermore, real-time high-speed observation reveals that the mechanisms that generate defects in the front-irradiated patterns and prevent defects in the back-irradiated patterns are closely related to vapor trapping. In contrast to the latter, in the former, vapor is trapped and delaminates the patterns from the substrate because the front of the patterns acts as a barrier to vapor venting.

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

Modeling of Powder Bed Manufacturing Defects

NASA Astrophysics Data System (ADS)

Mindt, H.-W.; Desmaison, O.; Megahed, M.; Peralta, A.; Neumann, J.

2018-01-01

Powder bed additive manufacturing offers unmatched capabilities. The deposition resolution achieved is extremely high enabling the production of innovative functional products and materials. Achieving the desired final quality is, however, hampered by many potential defects that have to be managed in due course of the manufacturing process. Defects observed in products manufactured via powder bed fusion have been studied experimentally. In this effort we have relied on experiments reported in the literature and—when experimental data were not sufficient—we have performed additional experiments providing an extended foundation for defect analysis. There is large interest in reducing the effort and cost of additive manufacturing process qualification and certification using integrated computational material engineering. A prerequisite is, however, that numerical methods can indeed capture defects. A multiscale multiphysics platform is developed and applied to predict and explain the origin of several defects that have been observed experimentally during laser-based powder bed fusion processes. The models utilized are briefly introduced. The ability of the models to capture the observed defects is verified. The root cause of the defects is explained by analyzing the numerical results thus confirming the ability of numerical methods to provide a foundation for rapid process qualification.

Maternal obesity and tobacco use modify the impact of genetic variants on the occurrence of conotruncal heart defects.

PubMed

Tang, Xinyu; Nick, Todd G; Cleves, Mario A; Erickson, Stephen W; Li, Ming; Li, Jingyun; MacLeod, Stewart L; Hobbs, Charlotte A

2014-01-01

Conotruncal heart defects (CTDs) are among the most severe birth defects worldwide. Studies of CTDs indicate both lifestyle behaviors and genetic variation contribute to the risk of CTDs. Based on a hybrid design using data from 616 case-parental and 1645 control-parental triads recruited for the National Birth Defects Prevention Study between 1997 and 2008, we investigated whether the occurrence of CTDs is associated with interactions between 921 maternal and/or fetal single nucleotide polymorphisms (SNPs) and maternal obesity and tobacco use. The maternal genotypes of the variants in the glutamate-cysteine ligase, catalytic subunit (GCLC) gene and the fetal genotypes of the variants in the glutathione S-transferase alpha 3 (GSTA3) gene were associated with an elevated risk of CTDs among obese mothers. The risk of delivering infants with CTDs among obese mothers carrying AC genotype for a variant in the GCLC gene (rs6458939) was 2.00 times the risk among those carrying CC genotype (95% confidence interval: 1.41, 2.38). The maternal genotypes of several variants in the glutathione-S-transferase (GST) family of genes and the fetal genotypes of the variants in the GCLC gene interacted with tobacco exposures to increase the risk of CTDs. Our study suggests that the genetic basis underlying susceptibility of the developing heart to the adverse effects of maternal obesity and tobacco use involve both maternal and embryonic genetic variants. These results may provide insights into the underlying pathophysiology of CTDs, and ultimately lead to novel prevention strategies.

Self healing of defected graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jianhui; Shi, Tuwan; Cai, Tuocheng

For electronics applications, defects in graphene are usually undesirable because of their ability to scatter charge carriers, thereby reduce the carrier mobility. It would be extremely useful if the damage can be repaired. In this work, we employ Raman spectroscopy, X-ray photoemission spectroscopy, transmission electron microscopy, and electrical measurements to study defects in graphene introduced by argon plasma bombardment. We have found that majority of these defects can be cured by a simple thermal annealing process. The self-healing is attributed to recombination of mobile carbon adatoms with vacancies. With increasing level of plasma induced damage, the self-healing becomes less effective.

Intrinsic point defects in off-stoichiometric Cu2ZnSnSe4: A neutron diffraction study

NASA Astrophysics Data System (ADS)

Gurieva, Galina; Valle Rios, Laura Elisa; Franz, Alexandra; Whitfield, Pamela; Schorr, Susan

2018-04-01

This work is an experimental study of intrinsic point defects in off-stoichiometric kesterite type CZTSe by means of neutron powder diffraction. We revealed the existence of copper vacancies (VCu), various cation anti site defects (CuZn, ZnCu, ZnSn, SnZn, and CuZn), as well as interstitials (Cui, Zni) in a wide range of off-stoichiometric polycrystalline powder samples synthesized by the solid state reaction. The results show that the point defects present in off-stoichiometric CZTSe agree with the off-stoichiometry type model, assuming certain cation substitutions accounting for charge balance. In addition to the known off-stoichiometry types A-H, new types (I-L) have been introduced. For the very first time, a correlation between the chemical composition of the CZTSe kesterite type phase and the occurring intrinsic point defects is presented. In addition to the off-stoichiometry type specific defects, the Cu/Zn disorder is always present in the CZTSe phase. In Cu-poor/Zn-rich CZTSe, a composition considered as the one that delivers the best photovoltaic performance, mainly copper vacancies, ZnCu and ZnSn anti sites are present. Also, this compositional region shows the lowest degree of Cu/Zn disorder.

Maternal residential proximity to chlorinated solvent emissions and birth defects in offspring: a case-control study.

PubMed

Brender, Jean D; Shinde, Mayura U; Zhan, F Benjamin; Gong, Xi; Langlois, Peter H

2014-11-19

Some studies have noted an association between maternal occupational exposures to chlorinated solvents and birth defects in offspring, but data are lacking on the potential impact of industrial air emissions of these solvents on birth defects. With data from the Texas Birth Defects Registry for births occurring in 1996-2008, we examined the relation between maternal residential proximity to industrial air releases of chlorinated solvents and birth defects in offspring of 60,613 case-mothers and 244,927 control-mothers. Maternal residential exposures to solvent emissions were estimated with metrics that took into account residential distances to industrial sources and annual amounts of chemicals released. Logistic regression was used to generate odds ratios and 95% confidence intervals for the associations between residential proximity to emissions of 14 chlorinated solvents and selected birth defects, including neural tube, oral cleft, limb deficiency, and congenital heart defects. All risk estimates were adjusted for year of delivery and maternal age, education, race/ethnicity, and public health region of residence. Relative to exposure risk values of 0, neural tube defects were associated with maternal residential exposures (exposure risk values >0) to several types of chlorinated solvents, most notably carbon tetrachloride (adjusted odds ratio [aOR] 1.42, 95% confidence interval [CI] 1.09, 1.86); chloroform (aOR 1.40, 95% CI 1.04, 1.87); ethyl chloride (aOR 1.39, 95% CI 1.08, 1.79); 1,1,2-trichloroethane (aOR 1.56, 95% CI 1.11, 2.18); and 1,2,3-trichloropropane (aOR 1.49, 95% CI 1.08, 2.06). Significant associations were also noted between a few chlorinated solvents and oral cleft, limb deficiency, and congenital heart defects. We observed stronger associations between some emissions and neural tube, oral cleft, and heart defects in offspring of mothers 35 years or older, such as spina bifida with carbon tetrachloride (aOR 2.49, 95% CI 1.09, 5.72), cleft palate

CERAMENT treatment of fracture defects (CERTiFy): protocol for a prospective, multicenter, randomized study investigating the use of CERAMENT™ BONE VOID FILLER in tibial plateau fractures

PubMed Central

2014-01-01

Background Bone graft substitutes are widely used for reconstruction of posttraumatic bone defects. However, their clinical significance in comparison to autologous bone grafting, the gold-standard in reconstruction of larger bone defects, still remains under debate. This prospective, randomized, controlled clinical study investigates the differences in pain, quality of life, and cost of care in the treatment of tibia plateau fractures-associated bone defects using either autologous bone grafting or bioresorbable hydroxyapatite/calcium sulphate cement (CERAMENT™|BONE VOID FILLER (CBVF)). Methods/Design CERTiFy (CERament™ Treatment of Fracture defects) is a prospective, multicenter, controlled, randomized trial. We plan to enroll 136 patients with fresh traumatic depression fractures of the proximal tibia (types AO 41-B2 and AO 41-B3) in 13 participating centers in Germany. Patients will be randomized to receive either autologous iliac crest bone graft or CBVF after reduction and osteosynthesis of the fracture to reconstruct the subchondral bone defect and prevent the subsidence of the articular surface. The primary outcome is the SF-12 Physical Component Summary at week 26. The co-primary endpoint is the pain level 26 weeks after surgery measured by a visual analog scale. The SF-12 Mental Component Summary after 26 weeks and costs of care will serve as key secondary endpoints. The study is designed to show non-inferiority of the CBVF treatment to the autologous iliac crest bone graft with respect to the physical component of quality of life. The pain level at 26 weeks after surgery is expected to be lower in the CERAMENT bone void filler treatment group. Discussion CERTiFy is the first randomized multicenter clinical trial designed to compare quality of life, pain, and cost of care in the use of the CBVF and the autologous iliac crest bone graft in the treatment of tibia plateau fractures. The results are expected to influence future treatment

Replication fork reversal triggers fork degradation in BRCA2-defective cells.

PubMed

Mijic, Sofija; Zellweger, Ralph; Chappidi, Nagaraja; Berti, Matteo; Jacobs, Kurt; Mutreja, Karun; Ursich, Sebastian; Ray Chaudhuri, Arnab; Nussenzweig, Andre; Janscak, Pavel; Lopes, Massimo

2017-10-16

Besides its role in homologous recombination, the tumor suppressor BRCA2 protects stalled replication forks from nucleolytic degradation. Defective fork stability contributes to chemotherapeutic sensitivity of BRCA2-defective tumors by yet-elusive mechanisms. Using DNA fiber spreading and direct visualization of replication intermediates, we report that reversed replication forks are entry points for fork degradation in BRCA2-defective cells. Besides MRE11 and PTIP, we show that RAD52 promotes stalled fork degradation and chromosomal breakage in BRCA2-defective cells. Inactivation of these factors restores reversed fork frequency and chromosome integrity in BRCA2-defective cells. Conversely, impairing fork reversal prevents fork degradation, but increases chromosomal breakage, uncoupling fork protection, and chromosome stability. We propose that BRCA2 is dispensable for RAD51-mediated fork reversal, but assembles stable RAD51 nucleofilaments on regressed arms, to protect them from degradation. Our data uncover the physiopathological relevance of fork reversal and illuminate a complex interplay of homologous recombination factors in fork remodeling and stability.BRCA2 is involved in both homologous recombination (HR) and the protection of stalled replication forks from degradation. Here the authors reveal how HR factors cooperate in fork remodeling, showing that BRCA2 supports RAD51 loading on the regressed arms of reversed replication forks to protect them from degradation.

Effect of hydrogen adsorption on the formation and annealing of Stone-Wales defects in graphene

NASA Astrophysics Data System (ADS)

Podlivaev, A. I.; Openov, L. A.

2015-12-01

The heights of energy barriers preventing the formation and annealing of Stone-Wales defects in graphene with a hydrogen atom adsorbed on the defect or in its immediate vicinity have been calculated using the atomistic computer simulation. It has been shown that, in the presence of hydrogen, both barriers are significantly lower than those in the absence of hydrogen. Based on the analysis of the potential energy surface, the frequency factors have been calculated for two different paths of the Stone-Wales transformation, and the temperature dependences of the corresponding annealing times of the defects have been found. The results obtained have been compared with the first-principles calculations and molecular dynamics data.

Study on control of defect mode in hybrid mirror chirped porous silicon photonic crystal

NASA Astrophysics Data System (ADS)

Chen, Ying; Luo, Pei; Han, Yangyang; Cui, Xingning; He, Lei

2018-03-01

Based on the optical resonance principle and the tight-binding theory, a hybrid mirror chirped porous silicon photonic crystal is proposed. The control of the defect mode in hybrid mirror chirped porous silicon photonic crystal is studied. Through the numerical simulation, the control regulations of the defect modes resulted by the number of the periodical layers for the fundamental unit and the cascading number of the chirped structures are analyzed, and the split and the degeneration of the defect modes resulted by the change of the relative location between the mirror structures and the quasi-mirror structures are discussed. The simulation results show that the band gap would be broadened with the increase of the chirp quantity and the layer number of unilateral chirp. Adjusting the structural parameters of the hybrid mirror structure, the multimode characteristics will occur in the band gap. The more the cascading number of the chirped units, the more the number of the filtering channels will be. In addition, with the increase of the relative location between the mirror structures and the quasi-mirror structures, the degeneration of the defect modes will occur and can obtain high Q value. The structure can provide effective theoretical references for the design the multi-channel filters and high Q value sensors.

Maternal diet modulates the risk for neural tube defects in a mouse model of diabetic pregnancy

PubMed Central

Kappen, Claudia; Kruger, Claudia; MacGowan, Jacalyn; Salbaum, J. Michael

2010-01-01

Pregnancies complicated by maternal diabetes have long been known to carry a higher risk for congenital malformations, such as neural tube defects. Using the FVB inbred mouse strain and the Streptozotocin-induced diabetes model, we tested whether the incidence of neural tube defects in diabetic pregnancies can be modulated by maternal diet. In a comparison of two commercial mouse diets, which are considered nutritionally replete, we found that maternal consumption of the unfavorable diet was associated with a more than three-fold higher rate of neural tube defects. Our results demonstrate that maternal diet can act as a modifier of the risk for abnormal development in high-risk pregnancies, and provide support for the possibility that neural tube defects in human diabetic pregnancies might be preventable by optimized maternal nutrition. PMID:20868740

Ce and La single- and double-substitutional defects in yttrium aluminum garnet: first-principles study.

PubMed

Muñoz-García, Ana Belén; Seijo, Luis

2011-02-10

The atomistic structure, energetics, and electronic structure of single-substitutional Ce and La defects and double-substitutional Ce-La defects in Ce,La-codoped yttrium aluminum garnet (YAG) Y(3)Al(5)O(12) have been studied by means of first-principles periodic boundary conditions density functional theory calculations. Single substitution of Y by Ce or by La produces atomistic expansions around the impurities, which are significantly smaller than the ionic radii mismatches and the overall lattice distortions are found to be confined within their second coordination spheres. In double-substitutional defects, the impurities tend to be as close as possible. La-codoping Ce:YAG provokes an anisotropic expansion around Ce defects. The Ce impurity introduces 4f occupied states in the 5.0 eV computed gap of YAG, peaking 0.25 eV above the top of the valence band, and empty 4f, 5d, and 6s states starting at 3.8 eV in the gap and spreading over the conduction band. La-codoping produces very small effects on the electronic structure of Ce:YAG, the most visible one being the decrease in covalent bonding with one of the oxygen atoms, which shifts 0.05 Å away from Ce and gets 0.04 Å closer to La in the most stable Ce-La double-substitutional defect.

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

Signification of distal urinary acidification defects in hypocitraturic patients

PubMed Central

Forni Ogna, Valentina; Blanchard, Anne; Vargas-Poussou, Rosa; Ogna, Adam; Baron, Stéphanie; Bertocchio, Jean-Philippe; Prot-Bertoye, Caroline; Nevoux, Jérôme; Dubourg, Julie; Maruani, Gérard; Mendes, Margarida; Garcia-Castaño, Alejandro; Treard, Cyrielle; Lepottier, Nelly; Houillier, Pascal; Courbebaisse, Marie

2017-01-01

Background and objectives Hypocitraturia has been associated with metabolic acidosis and mineral disorders. The aim of this study was to investigate the occurrence of urinary acidification defects underlying hypocitraturia. Materials and methods This retrospective observational study included 67 patients (32 men), aged 40.7±15.1 years with hypocitraturia (<1.67 mmol/24-h) and nephrolithiasis, nephrocalcinosis, and/or bone demineralization, referred to our center from 2000 to 2015. We aimed to assess renal distal acidification capacity, prevalence and mechanisms of urinary acidification defects. Patients with low baseline plasma HCO3- (<22 mmol/L) were studied by bicarbonate loading or furosemide/fludrocortisone tests. Patients with normal baseline plasma HCO3- had an ammonium-chloride challenge test. A normal response was a decrease in urinary pH <5.3 and an increase in urinary NH4+ ≥33 μmol/min and defined idiopathic hypocitraturia. Results Eleven patients (16.4%) had low HCO3- and overt distal acidification defect. Three had a mutation in the gene encoding AE1, 4 had Gougerot-Sjögren syndrome and no cause was found in the remaining 4 cases. Fifty-six patients (83.6%) had normal HCO3-; of those, 33 (58.9%) had idiopathic hypocitraturia. Among the 23 (41%) remaining patients, 12 were unable to increase urinary NH4+ excretion (among them, 8 were able to decrease urinary pH and 4 were not) whereas 11 were able to increase urinary NH4+ excretion but unable to decrease urinary pH. These 11 patients had higher fasting urinary calcium, reflecting bone resorption, than the other 12 patients: median 0.41 [0.24–0.47] vs. 0.22 [0.08–0.37] mmol/mmol creatinine (P = 0.04). Conclusions Patients with hypocitraturia and normal plasma HCO3- frequently show a latent acidification defect that can be further dissected into one of several subtypes based on urinary pH and NH4+ response to the acid load. Those patients with impaired urine acidification capacity but preserved NH

Residual defects of the external anal sphincter following primary repair: an observational study using transperineal ultrasound.

PubMed

Shek, K L; Guzman-Rojas, R; Dietz, H P

2014-12-01

Obstetric anal sphincter tears are common and an important factor in the etiology of anal incontinence. The objective of the study was to evaluate the prevalence of residual defects of the external anal sphincter (EAS) after primary repair of obstetric anal sphincter injury using four-dimensional (4D) transperineal ultrasound and to correlate sonographic findings of residual defects and levator avulsion with significant symptoms of anal incontinence, defined as St Mark's fecal incontinence score (SMIS) of ≥ 5. This was a retrospective observational study. One-hundred and forty women were seen after primary repair of obstetric anal sphincter tears in a dedicated perineal clinic at a tertiary hospital in Australia. They all underwent a standardized interview, and physical and 4D transperineal ultrasound examination. Mean follow-up interval was 1.9 months after delivery. Eighty-nine (64%) women had a 3a/3b tear, 28 (20%) a 3c/4(th) degree tear and 23 (16%) an unclassified 3(rd) degree tear. Thirty-five (25%) patients reported symptoms of anal incontinence. Nine had an SMIS of ≥ 5. A residual defect was found in 56 (40%) cases and levator avulsion in 27 (19%). On multivariate logistic regression, residual defects (P = 0.03; odds ratio (OR) = 6.38; 95% CI, 1.23-33.0) and levator avulsion (P = 0.047; OR = 4.38; 95% CI, 1.02-18.77) were found to be independent risk factors for anal incontinence. Residual defects of the EAS were found on transperineal ultrasound in 40% of women after primary repair of obstetric anal sphincter injuries. Although most were asymptomatic, residual anal sphincter defects and levator avulsion were associated with significant symptoms of anal incontinence as quantified using the SMIS. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd.

[Spatial distribution of birth defects among children aged 0 to 5 years and its relationship with soil chemical elements in Chongqing].

PubMed

Dong, Yan; Zhong, Zhao-hui; Li, Hong; Li, Jie; Wang, Ying-xiong; Peng, Bin; Zhang, Mao-zhong; Huang, Qiao; Yan, Ju; Xu, Fei-long

2013-10-01

To explore the correlation between the incidence of birth defects and the contents of soil elements so as to provide a scientific basis for screening the related pathogenic factors that inducing birth defects for the development of related preventive and control strategies. MapInfo 7.0 software was used to draw the maps on spatial distribution regarding the incidence rates of birth defects and the contents of 11 chemical elements in soil in the 33 studied areas. Variables on the two maps were superposed for analyzing the spatial correlation. SAS 8.0 software was used to analyze single factor, multi-factors and principal components as well as to comprehensively evaluate the degrees of relevance. Different incidence rates of birth defects showed in the maps of spatial distribution presented certain degrees of negative correlation with anomalies of soil chemical elements, including copper, chrome, iodine, selenium, zinc while positively correlated with the levels of lead. Results from the principal component regression equation indicating that the contents of copper(0.002), arsenic(-0.07), cadmium(0.05), chrome (-0.001), zinc (0.001), iodine(-0.03), lead (0.08), fluorine(-0.002)might serve as important factors that related to the prevalence of birth defects. Through the study on spatial distribution, we noticed that the incidence rates of birth defects were related to the contents of copper, chrome, iodine, selenium, zinc, lead in soil while the contents of chrome, iodine and lead might lead to the occurrence of birth defects.

Thermus and the Pink Discoloration Defect in Cheese

PubMed Central

Quigley, Lisa; O’Sullivan, Daniel J.; Daly, David; O’Sullivan, Orla; Burdikova, Zuzana; Vana, Rostislav; Beresford, Tom P.; Ross, R. Paul; Fitzgerald, Gerald F.; McSweeney, Paul L. H.; Giblin, Linda

2016-01-01

ABSTRACT A DNA sequencing-based strategy was applied to study the microbiology of Continental-type cheeses with a pink discoloration defect. The basis for this phenomenon has remained elusive, despite decades of research. The bacterial composition of cheese containing the defect was compared to that of control cheese using 16S rRNA gene and shotgun metagenomic sequencing as well as quantitative PCR (qPCR). Throughout, it was apparent that Thermus, a carotenoid-producing genus, was present at higher levels in defect-associated cheeses than in control cheeses. Prompted by this finding and data confirming the pink discoloration to be associated with the presence of a carotenoid, a culture-based approach was employed, and Thermus thermophilus was successfully cultured from defect-containing cheeses. The link between Thermus and the pinking phenomenon was then established through the cheese defect equivalent of Koch’s postulates when the defect was recreated by the reintroduction of a T. thermophilus isolate to a test cheese during the manufacturing process. IMPORTANCE Pink discoloration in cheese is a defect affecting many cheeses throughout the world, leading to significant financial loss for the dairy industry. Despite decades of research, the cause of this defect has remained elusive. The advent of high-throughput, next-generation sequencing has revolutionized the field of food microbiology and, with respect to this study, provided a means of testing a possible microbial basis for this defect. In this study, a combined 16S rRNA, whole-genome sequencing, and quantitative PCR approach was taken. This resulted in the identification of Thermus, a carotenoid-producing thermophile, in defect-associated cheeses and the recreation of the problem in cheeses to which Thermus was added. This finding has the potential to lead to new strategies to eliminate this defect, and our method represents an approach that can be employed to investigate the role of microbes in other

Repairing Nanoparticle Surface Defects.

PubMed

Marino, Emanuele; Kodger, Thomas E; Crisp, Ryan W; Timmerman, Dolf; MacArthur, Katherine E; Heggen, Marc; Schall, Peter

2017-10-23

Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We utilized atomically thin semiconductor nanoplatelets as a convenient platform for studying, both microscopically and spectroscopically, the development of defects during ligand exchange with the conductive ligands Na 4 SnS 4 and (NH 4 ) 4 Sn 2 S 6 . These defects can be repaired via mild chemical or thermal routes, through the addition of L-type ligands or wet annealing, respectively. This results in a higher-quality, conductive, colloidally stable nanomaterial that may be used as the active film in optoelectronic devices. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

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.

Punishment can promote defection in group-structured populations.

PubMed

Powers, Simon T; Taylor, Daniel J; Bryson, Joanna J

2012-10-21

Pro-social punishment, whereby cooperators punish defectors, is often suggested as a mechanism that maintains cooperation in large human groups. Importantly, models that support this idea have to date only allowed defectors to be the target of punishment. However, recent empirical work has demonstrated the existence of anti-social punishment in public goods games. That is, individuals that defect have been found to also punish cooperators. Some recent theoretical studies have found that such anti-social punishment can prevent the evolution of pro-social punishment and cooperation. However, the evolution of anti-social punishment in group-structured populations has not been formally addressed. Previous work has informally argued that group-structure must favour pro-social punishment. Here we formally investigate how two demographic factors, group size and dispersal frequency, affect selection pressures on pro- and anti-social punishment. Contrary to the suggestions of previous work, we find that anti-social punishment can prevent the evolution of pro-social punishment and cooperation under a range of group structures. Given that anti-social punishment has now been found in all studied extant human cultures, the claims of previous models showing the co-evolution of pro-social punishment and cooperation in group-structured populations should be re-evaluated. Copyright © 2012 Elsevier Ltd. All rights reserved.

ILT based defect simulation of inspection images accurately predicts mask defect printability on wafer

NASA Astrophysics Data System (ADS)

Deep, Prakash; Paninjath, Sankaranarayanan; Pereira, Mark; Buck, Peter

2016-05-01

At advanced technology nodes mask complexity has been increased because of large-scale use of resolution enhancement technologies (RET) which includes Optical Proximity Correction (OPC), Inverse Lithography Technology (ILT) and Source Mask Optimization (SMO). The number of defects detected during inspection of such mask increased drastically and differentiation of critical and non-critical defects are more challenging, complex and time consuming. Because of significant defectivity of EUVL masks and non-availability of actinic inspection, it is important and also challenging to predict the criticality of defects for printability on wafer. This is one of the significant barriers for the adoption of EUVL for semiconductor manufacturing. Techniques to decide criticality of defects from images captured using non actinic inspection images is desired till actinic inspection is not available. High resolution inspection of photomask images detects many defects which are used for process and mask qualification. Repairing all defects is not practical and probably not required, however it's imperative to know which defects are severe enough to impact wafer before repair. Additionally, wafer printability check is always desired after repairing a defect. AIMSTM review is the industry standard for this, however doing AIMSTM review for all defects is expensive and very time consuming. Fast, accurate and an economical mechanism is desired which can predict defect printability on wafer accurately and quickly from images captured using high resolution inspection machine. Predicting defect printability from such images is challenging due to the fact that the high resolution images do not correlate with actual mask contours. The challenge is increased due to use of different optical condition during inspection other than actual scanner condition, and defects found in such images do not have correlation with actual impact on wafer. Our automated defect simulation tool predicts

Congenital heart defects and extracardiac malformations.

PubMed

Rosa, Rosana Cardoso M; Rosa, Rafael Fabiano M; Zen, Paulo Ricardo G; Paskulin, Giorgio Adriano

2013-06-01

To review the association between congenital heart defects and extracardiac malformations. Scientific articles were searched in the Medline, Lilacs, and SciELO databases, using the descriptors "congenital heart disease," "congenital heart defects," "congenital cardiac malformations," "extracardiac defects," and "extracardiac malformations." All case series that specifically explored the association between congenital heart defects and extracardiac malformations were included. Congenital heart diseases are responsible for about 40% of birth defects, being one of the most common and severe malformations. Extracardiac malformations are observed in 7 to 50% of the patients with congenital heart disease, bringing a greater risk of comorbidity and mortality and increasing the risks related to heart surgery. Different studies have attempted to assess the presence of extracardiac abnormalities in patients with congenital heart disease. Among the changes described, those of the urinary tract are more often reported. However, no study has evaluated all patients in the same way. Extracardiac abnormalities are frequent among patients with congenital heart disease, and patients with these alterations may present an increased risk of morbimortality. Therefore, some authors have been discussing the importance and cost-effectiveness of screening these children for other malformations by complementary exams.

Color vision defects in school going children.

PubMed

Shrestha, R K; Joshi, M R; Shakya, S; Ghising, R

2010-01-01

Color vision defect can be observed in various diseases of optic nerve and retina and also a significant number of people suffer from the inherited condition of red and green color defect. A cross-sectional descriptive study was designed with purposive sampling of students from various schools of Kathmandu Valley. All children were subjected to color vision evaluation using Ishihara Isochromatic color plates along with other examination to rule out any other causes for color deficiency. A total of 2001 students were examined, 1050 male students and 951 females with mean age of 10.35 (+/- 2.75) and 10.54 (+/- 2.72) respectively. Among the total students examined, 2.1% had some form of color vision defects. Of the male population, 3.9% had color vision defects while none of the female was found with the deficiency. The prevalence of color vision defect in Nepal is significant and comparable with the prevalence quoted in studies from different countries.

Defects and Small Polarons on Oxide Surfaces

NASA Astrophysics Data System (ADS)

Janotti, Anderson

The presence and behavior of defects on the surface of oxides are central in many research areas, including catalysis, photochemistry, solar cells, and surface science in general. Experimental characterization of individual defects and their activities are challenging and often requires special preparations of the surface. First-principles calculations based on density functional theory are a powerful tool to study surfaces and defects, often providing information on properties that are difficult to access experimentally. Here we discuss the behavior of defects on oxide surfaces from the perspective on first-principles calculations. We use the oxygen vacancy on TiO2 surface as example, a system that has been extensively reported in the literature. Using DFT with a hybrid function, we discuss surface states induced by the defect and localization of the excess charge in the form of small polarons. We then discuss the effects of hydrogen and compare the behavior of these defects on the surface with that in the bulk. We also compare our recent results with previous theoretical studies and experiments. Finally, we generalize the findings on TiO2 to the surfaces of other oxides. This work was supported by the NSF.

Gadolinium substitution induced defect restructuring in multiferroic BiFeO3: case study by positron annihilation spectroscopy

NASA Astrophysics Data System (ADS)

Mukherjee, A.; Banerjee, M.; Basu, S.; Nambissan, P. M. G.; Pal, M.

2013-12-01

Positron annihilation spectroscopy (PAS) comprising of the measurements of positron lifetime and coincidence Doppler broadening spectra has been carried out to understand and monitor the evolution of the vacancy-type defects arising from the ionic deficiencies at lattice points of the multiferroic perovskite bismuth ferrite (BiFeO3) doped with 1, 5 and 10 at% gadolinium (Gd3+) ions. Negatively charged defects in the form of Bi3+ monovacancies (V_{Bi}^{3-} ) were present in the undoped nanocrystallites, which strongly trapped positrons. During the successive doping by Gd3+ ions, the positron trapping efficiency decreased while the doped ions combined with the vacancies to form complexes, which became neutral. A fraction of the positrons got annihilated at the crystallite surfaces too, being evident from the very large positron lifetimes obtained and confirming the nano-size-specific characteristics of the samples. Further, the intercrystallite regions provided favourable sites for orthopositronium formation, although in minute concentrations. The dopant ion-complex formation was also depicted clearly by the defect characteristic S-W plot. Also, the large change of electrical resistivity with Gd concentration has been explained nicely by invoking the defect information from the PAS study. The study has demonstrated the usefulness of an excellent method of defect identification in such a novel material system, which is vital information for exploiting them for further technological applications.

Printability of 1 x reticle defects for submicron design rules

NASA Astrophysics Data System (ADS)

Schurz, Dan L.; Flack, Warren W.; Newman, Gary

1997-02-01

As the push for improved resolution in wafer lithography intensifies and 0.18 micrometer devices are nearing production, the potential impact of subhalf micron reticle defects has become a growing concern. There have been several studies on the printability of subhalf-micron defects on high resolution reduction photolithography equipment. These studies have been extended to 1X lithography systems and more recently to advanced sub-micron 1X steppers. Previous studies have indicated that 0.20 micrometer opaque and 0.25 micrometer clear pinhole defects were at the margins of adversely impacting 0.65 micrometer lithography on a 1X stepper. However, due to the limited number of defects at these sizes on the reticle, definitive conclusions on printability could not be drawn. An additional study, using a three dimensional (3D) optical lithography simulation program, has shown defect size, proximity to an adjacent feature, and feature pitch to be significant factors contributing to reticle defect printability. Using the simulation findings as a guide, a new reticle was designed to contain an increased number of clear pinhole and opaque defects in the 0.15 to 0.30 micrometer range located in multiple pitches of both horizontal and vertical line/space pairs. Defect printability was determined using a 1X i-line projection stepper with focus and exposure optimized for nominal critical dimensions of 0.65 micrometer. The reticle and wafer defects were measured using low voltage SEM metrology. Simulation and experimental results have shown that pitch is the most significant contributor in the printability of clear pinhole, opaque, square and aspect ratio defects. In general, the impact of defect proximity to an adjacent feature is less extreme than the effect of pitch, but is more pronounced for clear pinhole defects. This study suggests that simulation can be a useful tool to help lithographers understand the behavior of reticle defects for particular layout design parameters

Traffic-Related Air Pollution and Selected Birth Defects in the San Joaquin Valley of California

PubMed Central

Padula, Amy M.; Tager, Ira B.; Carmichael, Suzan L.; Hammond, S. Katharine; Yang, Wei; Lurmann, Frederick W.; Shaw, Gary M.

2014-01-01

BACKGROUND Birth defects are a leading cause of infant morbidity and mortality. Studies suggest associations between environmental contaminants and some structural anomalies, although evidence is limited and several anomalies have not been investigated previously. METHODS We used data from the California Center of the National Birth Defects Prevention Study and the Children's Health and Air Pollution Study to estimate the odds of 26 congenital birth defect phenotypes with respect to quartiles of seven ambient air pollutant and traffic exposures in California during the first 2 months of pregnancy, 1997 to 2006 (874 cases and 849 controls). We calculated odds ratios (adjusted for maternal race/ethnicity, education, and vitamin use; aOR) for 11 phenotypes that had at least 40 cases. RESULTS Few odds ratios had confidence intervals that did not include 1.0. Odds of esophageal atresia were increased for the highest versus lowest of traffic density (aOR = 2.8, 95% confidence interval [CI], 1.1–7.4) and PM10 exposure (aOR 4.9; 95% CI, 1.4–17.2). PM10 was associated with a decreased risk of hydrocephaly (aOR= 0.3; 95% CI, 0.1–0.9) and CO with decreased risk of anotia/microtia (aOR = 0.4; 95% CI, 0.2–0.8) and transverse limb deficiency (aOR = 0.4; 95% CI, 0.2–0.9), again reflecting highest versus lowest quartile comparisons. CONCLUSION Most analyses showed no substantive association between air pollution and the selected birth defects with few exceptions of mixed results. PMID:24108522

Traffic-related air pollution and selected birth defects in the San Joaquin Valley of California.

PubMed

Padula, Amy M; Tager, Ira B; Carmichael, Suzan L; Hammond, S Katharine; Yang, Wei; Lurmann, Frederick W; Shaw, Gary M

2013-11-01

Birth defects are a leading cause of infant morbidity and mortality. Studies suggest associations between environmental contaminants and some structural anomalies, although evidence is limited and several anomalies have not been investigated previously. We used data from the California Center of the National Birth Defects Prevention Study and the Children's Health and Air Pollution Study to estimate the odds of 26 congenital birth defect phenotypes with respect to quartiles of seven ambient air pollutant and traffic exposures in California during the first 2 months of pregnancy, 1997 to 2006 (874 cases and 849 controls). We calculated odds ratios (adjusted for maternal race/ethnicity, education, and vitamin use; aOR) for 11 phenotypes that had at least 40 cases. Few odds ratios had confidence intervals that did not include 1.0. Odds of esophageal atresia were increased for the highest versus lowest of traffic density (aOR = 2.8, 95% confidence interval [CI], 1.1-7.4) and PM10 exposure (aOR 4.9; 95% CI, 1.4-17.2). PM₁₀ was associated with a decreased risk of hydrocephaly (aOR= 0.3; 95% CI, 0.1-0.9) and CO with decreased risk of anotia/microtia (aOR = 0.4; 95% CI, 0.2-0.8) and transverse limb deficiency (aOR = 0.4; 95% CI, 0.2-0.9), again reflecting highest versus lowest quartile comparisons. Most analyses showed no substantive association between air pollution and the selected birth defects with few exceptions of mixed results. Copyright © 2013 Wiley Periodicals, Inc.

Depth dependence of defect evolution and TED during annealing

NASA Astrophysics Data System (ADS)

Colombeau, B.; Cowern, N. E. B.; Cristiano, F.; Calvo, P.; Lamrani, Y.; Cherkashin, N.; Lampin, E.; Claverie, A.

2004-02-01

A quantitative transmission electron microscopy (TEM) study on the depth profile of extended defects, formed after Si implantation, has been carried out. Two different Si + implant conditions have been considered. TEM analysis for the highest energy/dose shows that {1 1 3} defects evolve into dislocation loops whilst the defect depth distribution remains unchanged as a function of annealing time. For the lowest energy/dose, {1 1 3} defects grow and dissolve while the defect band shrinks preferentially on the surface side. At the same time, extraction of boron transient enhanced diffusion (TED) as a function of depth shows a decrease of the supersaturation towards the surface, starting at the location of the defect band. The study clearly shows that in these systems the silicon surface is the principal sink for interstitials. The results provide a critical test of the ability of physical models to simulate defect evolution and TED.

Malnutrition-related early childhood exposures and enamel defects in the permanent dentition: A longitudinal study from the Bolivian Amazon.

PubMed

Masterson, Erin E; Fitzpatrick, Annette L; Enquobahrie, Daniel A; Mancl, Lloyd A; Conde, Esther; Hujoel, Philippe P

2017-10-01

We investigated the relationship between early childhood malnutrition-related measures and subsequent enamel defects in the permanent dentition. This cohort study included 349 Amerindian adolescents (10-17 years, 52% male) from the Bolivian Amazon. Exposures included: stunted growth (height-for-age z-scores), underweight (weight-for-age z-scores), anemia (hemoglobin), acute inflammation (C-reactive protein) and parasitic infection (hookworm). We measured the occurrence (no/yes) and extent (<1/3, 1/3-2/3, >2/3) of enamel defects. We estimated associations between childhood exposures and enamel defect measures using log-binomial and multinomial logistic regression. The prevalence of an enamel defect characterized by an orange peel texture on a large central depression on the labial surface of the central maxillary incisors was 92.3%. During childhood (1-4 years), participants had a high prevalence of stunted growth (75.2%), anemia (56.9%), acute inflammation (39.1%), and hookworm infection (49.6%). We observed associations between childhood height-for-age (OR = 0.65; P = 0.028 for >2/3 extent vs. no EH) and gastrointestinal hookworm infection (OR = 3.43; P = 0.035 for >2/3 extent vs. no defects or <1/3 extent) with enamel defects. The study describes a possibly novel form of enamel hypoplasia and provides evidence for associations of malnutrition-related measures in early childhood, including stunted growth and parasitic helminth infection, with the observed enamel defects. © 2017 Wiley Periodicals, Inc.

Eddy current inspection of weld defects in tubing

NASA Technical Reports Server (NTRS)

Katragadda, G.; Lord, W.

1992-01-01

An approach using differential probes for the inspection of weld defects in tubing is studied. Finite element analysis is used to model the weld regions and defects. Impedance plane signals are predicted for different weld defect types and compared wherever possible with signals from actual welds in tubing. Results show that detection and sizing of defects in tubing is possible using differential eddy current techniques. The phase angle of the impedance plane trajectory gives a good indication of the sizing of the crack. Data on the type of defect can be obtained from the shape of the impedance plane trajectory and the phase. Depending on the skin depth, detection of outer wall, inner wall, and subsurface defects is possible.

Defect reduction for semiconductor memory applications using jet and flash imprint lithography

NASA Astrophysics Data System (ADS)

Ye, Zhengmao; Luo, Kang; Lu, Xiaoming; Fletcher, Brian; Liu, Weijun; Xu, Frank; LaBrake, Dwayne; Resnick, Douglas J.; Sreenivasan, S. V.

2012-07-01

Acceptance of imprint lithography for manufacturing will require demonstration that it can attain defect levels commensurate with the defect specifications of high-end memory devices. Defects occurring during imprinting can generally be broken into two categories; random defects and repeating defects. Examples of random defects include fluid phase imprint defects, such as bubbles, and solid phase imprint defects, such as line collapse. Examples of repeater defects include mask fabrication defects and particle induced defects. Previous studies indicated that soft particles cause nonrepeating defects. Hard particles, on the other hand, can cause either permanent resist plugging or mask damage. In a previous study, two specific defect types were examined; random nonfill defects occurring during the resist filling process and repeater defects caused by interactions with particles on the substrate. We attempted to identify the different types of imprint defect types using a mask with line/space patterns at dimensions as small as 26 nm. An Imprio 500 twenty-wafer per hour development tool was used to study the various defect types. The imprint defect density was reduced nearly four orders of magnitude, down to ˜4/cm2 in a period of two years following the availability of low defect imprint masks at 26-nm half-pitch. This reduction was achieved by identifying the root cause of various defects and then taking the appropriate corrective action.

Raman study of the effect of LED light on grafted bone defects

NASA Astrophysics Data System (ADS)

Soares, Luiz G. G. P.; Aciole, Jouber M. S.; Aciole, Gilbeth T. S.; Barbosa, Artur F. S.; Silveira-Júnior, Landulfo; Pinheiro, Antônio L. B.

2013-03-01

Benefits of the isolated or combined use light and biomaterials on bone healing have been suggested. Our group has used several models to assess the effects of laser on bone. A Raman spectral analysis on surgical bone defects grafted or not with Hydroxyapatite (HA), treated or not with LED was carried out. 40 rats were divided into 4 groups. On Group I the defect was filled with the clot. On Group II, the defect was filled with the HA. On groups III the defect was filled with Clot and further irradiated with LED and on group IV the defects was filled with the HA and further irradiated with LED. LED (λ850 +/- 10nm, 150mW, A= 0.5cm2, 68s, 20 J/cm2 per session, 140 J/cm2 per treatment) was applied at 48 h intervals during 15 days. Specimens were taken after 15 and 30 days after surgery and kept on liquid nitrogen, and underwent Raman analysis. For this, the peak of hydroxyapatite (~960 cm-1) was used as marker of bone mineralization. Significant difference was observed at both times (p<0.05). When the biomaterial was used higher peaks were observed. Association with LED further improved the intensity. Conclusion: It is concluded that LED light improved the effect of the HA.

First-principles study of uranium carbide: Accommodation of point defects and of helium, xenon, and oxygen impurities

NASA Astrophysics Data System (ADS)

Freyss, Michel

2010-01-01

Point defects and volatile impurities (helium, xenon, oxygen) in uranium monocarbide UC are studied by first-principles calculations. Preliminarily, bulk properties of UC and of two other uranium carbide phases, UC2 and U2C3 , are calculated in order to compare them to experimental data and to get confidence in the use of the generalized gradient approximation for this class of compounds. The subsequent study of different types of point defects shows that the carbon sublattice best accommodates the defects. The perturbation of the crystal structure induced by the defects is weak and the interaction between defects is found short range. Interstitial carbon dumbbells possibly play an important role in the diffusion of carbon atoms. The most favorable location of diluted helium, xenon, and oxygen impurities in the UC crystal lattice is then determined. The rare-gas atoms occupy preferably a uranium substitution site or a uranium site in a U-C bivacancy. But their incorporation in UC is, however, not energetically favorable, especially for xenon, suggesting their propensity to diffuse in the material and/or form bubbles. On the other hand, oxygen atoms are very favorably incorporated as diluted atoms in the UC lattice, confirming the easy oxidation of UC. The oxygen atoms preferably occupy a carbon substitution site or the carbon site of a U-C bivacancy. Our results are compared to available experimental data on UC and to similar studies by first-principles calculations for other carbides and nitrides with the rock-salt structure.

Effects of boron-nitride substrates on Stone-Wales defect formation in graphene: An ab initio molecular dynamics study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, K.; Xiao, H. Y.; Zhang, Y.

2014-05-19

Ab initio molecular dynamics simulations are performed to investigate the effects of a boron nitride (BN) substrate on Stone-Wales (SW) defect formation and recovery in graphene. It is found that SW defects can be created by an off-plane recoil atom that interacts with the BN substrate. A mechanism with complete bond breakage for formation of SW defects in suspended graphene is also revealed for recoils at large displacement angles. In addition, further irradiation can result in recovery of the SW defects through a bond rotation mechanism in both graphene and graphene/BN, and the substrate has little effect on the recoverymore » process. This study indicates that the BN substrate enhances the irradiation resistance of graphene.« less

Positron annihilation studies of vacancy related defects in ceramic and thin film Pb(Zr,Ti)O3 materials

NASA Astrophysics Data System (ADS)

Keeble, D. J.; Krishnan, A.; Umlor, M. T.; Lynn, K. G.; Warren, W. L.; Dimos, D.; Tuttle, B. A.

Preliminary positron annihilation studies of ceramic and thin film Pb(Zr,Ti)O3 (PZT) materials have been completed. This paper examines effects of processing conditions on vacancy related defects. Positron lifetime measurements on bulk PLZT plates showed an increase in positron trapping to a defect state with increasing grain size consistent with trapping to lead vacancy related defects formed through lead oxide loss during processing. Variable energy positron beam measurements were completed on bulk PLZT plates, sol-gel PZT thin films, and laser ablated PLZT thin films. Films processed in a reduced oxygen atmosphere were found to give a higher S-parameter, due to an increase in concentration of neutral or negatively charged vacancy type defects, compared with material processed in an oxidizing ambient.

[Experimental study on loading naringin composite scaffolds for repairing rabbit osteochondral defects].

PubMed

Huang, Junbo; Wang, Shiyong; Zhang, Xiaomin; Li, Gen; Ji, Puzhong; Zhao, Hongbin

2017-04-01

To investigate the performance of loading naringin composite scaffolds and its effects on repair of osteochondral defects. The loading naringin and unloading naringin sustained release microspheres were prepared by W/O/W method; with the materials of the attpulgite and the collagen type I, the loading naringin, unloading naringin, and loading transforming growth factor β 1 (TGF-β 1 ) osteochondral composite scaffolds were constructed respectively by "3 layers sandwich method". The effect of sustained-release of loading naringin microspheres, the morphology of the composite scaffolds, and the biocompatibility were evaluated respectively by releasing in vitro , scanning electron microscope, and cell counting kit 8. Forty Japanese white rabbits were randomly divided into groups A, B, C, and D, 10 rabbits each group. After a osteochondral defect of 4.5 mm in diameter and 4 mm in depth was made in the intercondylar fossa of two femurs. Defect was not repaired in group A (blank control), and defect was repaired with unloading naringin composite scaffolds (negative control group), loading naringin composite scaffolds (experimental group), and loading TGF-β 1 composite scaffolds (positive control group) in groups B, C, and D respectively. At 3 and 6 months after repair, the intercondylar fossa was harvested for the general, HE staining, and toluidine blue staining to observe the repair effect. Western blot was used to detect the expression of collagen type II in the new cartilage. Loading naringin microspheres had good effect of sustained-release; the osteochondral composite scaffolds had good porosity; the cell proliferation rate on loading naringin composite scaffold was increased significantly when compared with unloading naringin scaffold ( P <0.05). General observation revealed that defect range of groups C and D was reduced significantly when compared with groups A and B at 3 months after repair; at 6 months after repair, defects of group C were covered by new