bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing dengue transmission risk and a vector control intervention using entomological and immunological indices in Thailand: study protocol for a cluster-randomized controlled trial
Authors: Overgaard Hans J. , Pientong Chamsai , Thaewnongiew Kesorn , Bangs Michael J. , Ekalaksananan Tipaya , Aromseree Sirinart , Phanitchat Thipruethai , Phanthanawiboon Supranee , Fustec Benedicte , Corbel Vincent , Cerqueira Dominique , Alexander Neal
Published: February 2018

Background

Dengue fever is the most common and widespread mosquito-borne arboviral disease in the world. There is a compelling need for cost-effective approaches and practical tools that can reliably measure real-time dengue transmission dynamics that enable more accurate and useful predictions of incidence and outbreaks. Sensitive surveillance tools do not exist today, and only a small handful of new control strategies are available. Vector control remains at the forefront for combating dengue transmission. However, the effectiveness of many current vector control interventions is fraught with inherent weaknesses. No single vector control method is effective enough to control both vector populations and disease transmission. Evaluations of novel larval and adult control interventions are needed.

Methods/design

A cluster-randomized controlled trial will be carried out between 2017 and 2019 in urban community clusters in Khon Kaen and Roi Et cities, northeastern Thailand. The effectiveness of a pyriproxyfen/spinosad combination treatment of permanent water storage containers will be evaluated on epidemiological and entomological outcomes, including dengue incidence, number of female adult dengue vectors infected or not infected with dengue virus (DENV), human exposure to Aedes mosquito bites, and several other indices. These indices will also be used to develop predictive models for dengue transmission and impending outbreaks. Epidemiological and entomological data will be collected continuously for 2 years, with the intervention implemented after 1 year.

Discussion

The aims of the trial are to simultaneously evaluate the efficacy of an innovative dengue vector control intervention and developing predictive dengue models. Assessment of human exposure to mosquito bites by detecting antibodies generated against Aedes saliva proteins in human blood samples has, so far, not been applied in dengue epidemiological risk assessment and disease surveillance methodologies. Likewise, DENV detection in mosquitoes (adult and immature stages) has not been used in any practical way for routine disease surveillance strategies. The integration of multiple outcome measures will assist health authorities to better predict outbreaks for planning and applying focal and timely interventions. The trial outcomes will not only be important for Thailand, but also for the entire Southeast Asian region and further afield.

Trial registration

ISRCTN, ISRCTN73606171. Registered on 23 June 2017.
Long-term effects on the progress of neuropathy after diabetic Charcot foot: an 8.5-year prospective case–control study
Authors: Jansen Rasmus Bo , Møller Christensen Tomas , Bülow Jens , Rørdam Lene , Holstein Per E. , Svendsen Ole Lander
Published: February 2018

Objective

Charcot foot is a severe complication to diabetes mellitus, associated with diabetic neuropathy. Any long-term effects of a Charcot foot on the progress of neuropathy are still largely unexplored. The objective was to investigate whether a previous Charcot foot had any long-term effects on the progress of neuropathy.

Results

An 8.5-year follow-up case–control study of 49 individuals with diabetes mellitus, 24 of whom also had Charcot foot at baseline visit in 2005–2007. Neuropathy was assessed with a questionnaire, biothesiometry, heart rate variability and venous occlusion plethysmography. Of the 49 baseline participants, 22 were able to participate in the follow-up. Twelve had passed away in the meantime. Heart rate variability was unchanged in both groups; from 9.7 to 7.2 beats/min (p = 0.053) in the Charcot group, and 14.3 to 12.6 beats/min (p = 0.762) in the control group. Somato-sensoric neuropathy showed no difference between baseline and follow-up in the Charcot group (from 39.1 to 38.5 V) (p = 0.946), but a significantly worsened sensitivity in the control group (from 25.1 to 38.9 V) (p = 0.002). In conclusion, we found that any differences in somatic or cardial autonomic neuropathy present at baseline had disappeared at follow-up after 8.5 years.
Efficient policing for screen mirroring traffic
Authors: Loizides Orestis-Stavros , Kastrinakis Marios , Badawy Ghada , Smadi Mohammed N. , Murray David , Koutsakis Polychronis
Published: February 2018

The greediness of multimedia applications in terms of their bandwidth demands calls for new and efficient network traffic control mechanisms, especially in wireless networks where the bandwidth is limited. In an enterprise-like environment, an additional burden is expected to be added to the network by screen mirroring traffic. Smart mobile devices are displacing personal computers in many daily applications but at the same time users still need to use a large display, keyboard and mouse. Hence, the transmission of low-latency, high fidelity video over a Wi-Fi link can lead to significant unfairness among users in terms of the bandwidth that is available to them, if this wireless video traffic is not accurately policed. In this work, we focus on the problem of policing screen mirroring traffic. We evaluate various classic and new traffic policing mechanisms, and we propose a new mechanism which is shown to clearly outperform all other mechanisms, including the widely used token bucket policer.
Prevalence of extended-spectrum-β-lactamase-producing Enterobacteriaceae: first systematic meta-analysis report from Pakistan
Authors: Abrar Samyyia , Hussain Shahida , Khan Rehan Ahmad , Ul Ain Noor , Haider Hayat , Riaz Saba
Published: February 2018

Background

South-Asia is known as a hub for multidrug-resistant (MDR) bacteria. Unfortunately, proper surveillance and documentation of MDR pathogens is lacking in Pakistan. The alarming increase in the prevalence of extended-spectrum β-lactamase (ESBL)-producingEnterobacteriaceaeis a serious problem. From this perspective, we analysed published data regarding ESBL-producingEnterobacteriaceaein different regions of Pakistan.

Methods

A meta-analysis was performed to determine the prevalence of ESBL-producingEnterobacteriaceaein Pakistan. A Web-based search was conducted in electronic databases, including PubMed, Scopus and PakMedi Net (for non-indexed Pakistani journals). Articles published (in either indexed or non-indexed journals) between January 2002 and July 2016 were included in the study. Relevant data were extracted, and statistical analysis was performed using theMetapropcommand of STATA version 14.1.

Results

A total of 68 studies were identified from the electronic data base search, and 55 of these studies met our inclusion criteria. Pakistan’s overall pooled proportion of ESBL-producers was 0.40 (95% CI: 0.34–0.47). The overall heterogeneity was significant (I2 = 99.75%,p < 0.001), and significant ES = 0 (Z = 18.41,p < 0.001) was found. OXA, SHV, TEM and CTX-M were the most commonly found gene variants for ESBLs in these studies.

Conclusion

The prevalence of ESBL-producingEnterobacteriaceaeis high in Pakistan. Little is known about the annual frequency of ESBLs and their prevalence in different provinces of Pakistan. No data are available regarding ESBL frequency in Baluchistan. This underscores an urgent demand for regular surveillance to address this antimicrobial resistance problem. Surveillance to better understand the annual ESBL burden is crucial to improve national and regional guidelines.
Differentiating the structure of PtNi octahedral nanoparticles through combined ADF–EDX simulations
Authors: MacArthur Katherine E. , Heggen Marc , Dunin-Borkowski Rafal E.
Published: February 2018

Advances in catalysis rely on the synthesis and characterisation of nanoparticles that have tailored structures and compositions. Although energy-dispersive X-ray (EDX) spectroscopy can be used to study local variations in the compositions of individual supported nanoparticles on the atomic-scale in the scanning transmission electron microscope, electron beam induced damage and contamination can preclude the use of long exposure times and tomographic approaches. Here, we perform simulations of EDX maps of seven different octahedral PtNi nanoparticles for a selection of crystallographic orientations and tilts, to evaluate which of them can be distinguished from elemental mapping performed in only one orientation.
Comparison of Natural Language Processing and Manual Coding for the Identification of Cross-Sectional Imaging Reports Suspicious for Lung Cancer
Authors: Wadia Roxanne , Akgun Kathleen , Brandt Cynthia , Fenton Brenda T. , Levin Woody , Marple Andrew H. , Garla Vijay , Rose Michal G. , Taddei Tamar , Taylor Caroline
Published: February 2018

Purpose

To compare the accuracy and reliability of a natural language processing (NLP) algorithm with manual coding by radiologists, and the combination of the two methods, for the identification of patients whose computed tomography (CT) reports raised the concern for lung cancer.

Methods

An NLP algorithm was developed using Clinical Text Analysis and Knowledge Extraction System (cTAKES) with the Yale cTAKES Extensions and trained to differentiate between language indicating benign lesions and lesions concerning for lung cancer. A random sample of 450 chest CT reports performed at Veterans Affairs Connecticut Healthcare System between January 2014 and July 2015 was selected. A reference standard was created by the manual review of reports to determine if the text stated that follow-up was needed for concern for cancer. The NLP algorithm was applied to all reports and compared with case identification using the manual coding by the radiologists.

Results

A total of 450 reports representing 428 patients were analyzed. NLP had higher sensitivity and lower specificity than manual coding (77.3% v 51.5% and 72.5% v 82.5%, respectively). NLP and manual coding had similar positive predictive values (88.4% v 88.9%), and NLP had a higher negative predictive value than manual coding (54% v 38.5%). When NLP and manual coding were combined, sensitivity increased to 92.3%, with a decrease in specificity to 62.85%. Combined NLP and manual coding had a positive predictive value of 87.0% and a negative predictive value of 75.2%.

Conclusion

Our NLP algorithm was more sensitive than manual coding of CT chest reports for the identification of patients who required follow-up for suspicion of lung cancer. The combination of NLP and manual coding is a sensitive way to identify patients who need further workup for lung cancer.
Structured Approach for Evaluating Strategies for Cancer Ascertainment Using Large-Scale Electronic Health Record Data
Authors: Earles Ashley , Liu Lin , Bustamante Ranier , Coke Pat , Lynch Julie , Messer Karen , Martínez María Elena , Murphy James D. , Williams Christina D. , Fisher Deborah A. , Provenzale Dawn T. , Gawron Andrew J. , Kaltenbach Tonya , Gupta Samir
Published: February 2018

Purpose

Cancer ascertainment using large-scale electronic health records is a challenge. Our aim was to propose and apply a structured approach for evaluating multiple candidate approaches for cancer ascertainment using colorectal cancer (CRC) ascertainment within the US Department of Veterans Affairs (VA) as a use case.

Methods

The proposed approach for evaluating cancer ascertainment strategies includes assessment of individual strategy performance, comparison of agreement across strategies, and review of discordant diagnoses. We applied this approach to compare three strategies for CRC ascertainment within the VA: administrative claims data consisting of International Classification of Diseases, Ninth Revision (ICD9) diagnosis codes; the VA Central Cancer Registry (VACCR); and the newly accessible Oncology Domain, consisting of cases abstracted by local cancer registrars. The study sample consisted of 1,839,043 veterans with index colonoscopy performed from 1999 to 2014. Strategy-specific performance was estimated based on manual record review of 100 candidate CRC cases and 100 colonoscopy controls. Strategies were further compared using Cohen’s κ and focused review of discordant CRC diagnoses.

Results

A total of 92,197 individuals met at least one CRC definition. All three strategies had high sensitivity and specificity for incident CRC. However, the ICD9-based strategy demonstrated poor positive predictive value (58%). VACCR and Oncology Domain had almost perfect agreement with each other (κ, 0.87) but only moderate agreement with ICD9-based diagnoses (κ, 0.51 and 0.57, respectively). Among discordant cases reviewed, 15% of ICD9-positive but VACCR- or Oncology Domain–negative cases had incident CRC.

Conclusion

Evaluating novel strategies for identifying cancer requires a structured approach, including validation against manual record review, agreement among candidate strategies, and focused review of discordant findings. Without careful assessment of ascertainment methods, analyses may be subject to bias and limited in clinical impact.
Electrodeposition of Tungsten Oxide for Highly Sensitive Acetone Detection at Room Temperature
Authors: Wang Zu-Gang , Zhang Miao-Rong , Peng Hong-Dan , Jiang Qing-Mei , Hou Fei , Zhu Zhong-Li , Pan Ge-Bo
Published: February 2018

Tungsten oxide thin films were electrochemically deposited onto gallium nitride for the first time and directly used for the fabrication of an acetone sensor. This sensor could operate at room temperature and had high sensitivity, fast response, and long-term stability. Moreover, the detection limit of the sensor could reach 0.1 ppm, implying its potential application in non-invasive detection of diabetes.
Cross sectional study to determine chloroquine resistance among Plasmodium falciparum clinical isolates from Khartoum, Sudan
Authors: Abdulla Mohammed Walaa Salah , Yasin Kyakonye , Mahgoub N.S. , Abdel Hamid Muzamil Mahdi
Published: February 2018

Background:  Malaria continues to present a global health threat; the World Health Organization (WHO) reported 214 million cases of malaria by the year 2015 with a death rate of 438000. Sudan is endemic to malaria with over 95% of malaria cases due to Plasmodium falciparum. Chloroquine is a well-established drug in the treatment of P. falciparum malaria although its use has declined since its introduction as the drug of choice in treatment of malaria in Sudan. The mechanism of resistance has been attributed to mutations in P. falciparum Chloroquine resistance transporter gene coding for a key food vacuole proteins. In current study we aimed at verifying the genetic cause of resistance to Chloroquine in field isolates of P. falciparum.

Methods: Twenty P. falciparum cases were diagnosed from East Nile hospital in Khartoum and recruited in the investigation. Nested PCR was conducted to isolate mutation region in the PfCRT gene and the amplicons were sequenced using Sanger sequencing technique (Macrogen, Soule Korea).

Results: 16/20 (80%) of the field isolates contained base pair mutation of codon 76 in the pfcrt gene thus being resistant to chloroquine treatment and only 4/20 (20%) did not contain such mutation.

Conclusions: High treatment failures associated with Chloroquine treatment is evident of the high prevalence of mutant strains of P. falciparum field isolates thus suggesting the reduced relevance of Chloroquine as a treatment choice in the management of P. falciparum malaria.
Cryopreservation of orchid seeds through rapid and step freezing methods
Authors: Cerna Marco , Valdivieso Paulina , Cella Rino , Mátyás Bence , Aucapiña Cristina
Published: February 2018

Ecuador has a great variety of climatic regions that potentiate biodiversity. The family Orchidaceae constitutes one of the most important of the country, having identified about 4032 species with a high degree of endemism, therefore the development and research of alternative methods of storage and conservation of species is a strategy of primary interest for researchers and for society in general. In cryopreservation, temperatures reach below -190°C in order to paralyze the chemical reactions and keep the plant material viable for long periods. The present research focuses on the development of protocols for cryopreservation of seeds, aimed at the preservation of biodiversity, focusing on the family Orchidaceae, for the subsequent generation of a seed bank. The assays were performed on seeds of Epidendrum quitensium, Sobralia rosea, and Epidendrum anderssonii. Two freezing rates were tested: rapid freezing at -196°C; and step freezing at -22°C, -60°C to 196°C, further analyzed four combinations from Dimethylsulfoxide DMSO, glycerol and sucrose (DMSO 1M; DMSO 1M + glycerol 1M; DMSO 1M + sucrose 1M; DMSO 1M + glycerol 0,5M + sucrose 0,5M). The best results were obtained both in rapid and stepped freezing without the use of cryo-protective substances, by introducing the seeds directly into liquid nitrogen. Species of the genus Epidendrum presented a more efficient response in comparison to Sobralia. The viability of the seeds was evaluated by the tetrazolium test.
ЦЕЛЕВЫЕ ОРИЕНТИРЫ ПРОФЕССИОНАЛЬНОЙ ПОДГОТОВКИ СТУДЕНТОВ ТЕХНОЛОГИЧЕСКОГО ПРОФИЛЯ
Authors: Litovchenko Anna Sergeevna , Gavrilova Nadezhda Valerievna , Rozlovan Valentina Valerievna
Published: February 2018

В статье уделяется внимание трем вопросам: развитие навыков проектирования студентов Технологического профиля обучения; развитие эстетической культуры студентов Технологического профиля обучения; формирование исследовательской компетенции студентов профессионально-педагогических направлений.По первому вопросу изучен процесс развития навыков проектирования, где выделены такие определения, как «макетирование», «проектирование», «навык».При изучении второго вопроса проанализирован процесс развития эстетической культуры при обучении художественным дисциплинам, где обозначается определение понятия «развитие эстетической культуры студентов Вуза».Рассматривая третий вопрос подробно проанализирован процесс формирования исследовательской компетенции студентов профессионально-педагогических направлений.
МОДЕЛЬ ОПТИМИЗАЦИИ ДВИГАТЕЛЬНОЙ АКТИВНОСТИ ДЕТЕЙ МЛАДШЕГО ШКОЛЬНОГО ВОЗРАСТА, ПРОЖИВАЮЩИХ В УСЛОВИЯХ СЕВЕРНОГО ГОРОДА
Authors: Busheva Zhanna Ildarovna
Published: February 2018

Экстремальные условия Севера, компьютеризация, интернет- и гаджет-зависимость, высокие физические и умственные нагрузки детей-северян негативно сказываются на состоянии здоровья подрастающего поколения. Трудно переоценить роль двигательной активности в расширении функциональных возможностей развивающегося организма, так как недостаток локомоций может привести к патологическим сдвигам в организме. В статье на основе анализа подходов к понятию «двигательная активность» и особенностей северного города, предложена модель оптимизации двигательной активности детей младшего школьного возраста, состоящая из 6 блоков: целевого, диагностико-аналитического, содержательного, процессуально-деятельностного, рефлексивно-оценочного и результативного. Исследование проводилось на базе городских школ Сургута и Сургутского района Ханты-Мансийского автономного округа-Югры. В ходе исследования были выявлены наиболее приоритетные организационные формы двигательной активности детей младшего школьного возраста, живущих в условиях северного города. Модель оптимизации двигательной активности детей младшего школьного возраста позволяет создать необходимый оптимальный объем и контролировать двигательную активность детей младшего школьного возраста.Цель. Целью наших исследований было создание модели оптимизации двигательной активности детей младшего школьного возраста, живущих в условиях северного города.Метод или методология проведения работы. Методология работы предполагает использование анализа и синтеза материалов исследований, а также собственно метод моделирования.Результаты. В ходе исследования разработана модель оптимизации двигательной активности детей-северян младшего школьного возраста, приведены ее содержательные характеристики.Область применения результатов. Результаты могут быть применены педагогами в образовательном процессе профессионального образования.
СИНЕРГЕТИЧЕСКИЙ ПОДХОД К ВОСПИТАТЕЛЬНОЙ РАБОТЕ СОВРЕМЕННОЙ ШКОЛЫ
Authors: Tovarischeva Fekla Dmitrievna , Sofronov Rodion Pavlovich
Published: February 2018

Цель: статья посвящена актуальной проблеме организации управления воспитательной системы школы в условиях новой социально-образовательной ситуации, требующей иных подходов к развитию образования. Предметом исследования выступает влияние процессов, происходящих на микроуровне, на развитие воспитательной системы школы. Предметом педагогического влияния в этом случае становится управление развитием личности.Методы и методология проведения работы: основу исследования образуют методы «широкого фронта» (К. Лоренц), дополнительности, герменевтический, антиномный (аналитический) методы. Методология в данной статье определяется как система принципов и способов организации и построения теоретической и практической воспитательной деятельности (принцип системности, синергетический принцип самоорганизации, гуманизации и т.д.).Результаты: выявлены основные объективные и субъективные условия, содействующие развитию управления воспитательной системой школы: теоретическое вооружение педагогов инновационными технологиями воспитательной деятельности; формирование стимулов для развития личности, то есть наличие организации воспитательной деятельности, условий и механизмов ее осуществления.Область применения результатов: результаты исследования могут быть применены в сфере образования, специализирующимся по управлению образованием.
ВЗАИМОСВЯЗЬ ПРОФЕССИОНАЛЬНОЙ МОБИЛЬНОСТИ И КОМПЕТЕНТНОСТИ УЧИТЕЛЯ СЕЛЬСКОЙ ШКОЛЫ В УСЛОВИЯХ МОДЕРНИЗАЦИИ ОБРАЗОВАНИЯ
Authors: Gavrilova Olga Vladimirovna , Zakharova Elena Aleksandrovna
Published: February 2018

Цель. Статья посвящена профессиональной деятельности учителя в условиях модернизации образования. Предметом анализа выступает взаимосвязь профессиональной мобильности и компетентности учителя сельской школы и условия ее формирования. Авторы ставят целью раскрыть категории понятий «профессиональная мобильность», «профессиональная компетентность» учителя сельской школы и определить их сущность в условиях изменения парадигмы образования.Результаты. Результаты работы заключаются в том, что авторы дают определение понятий «профессиональная мобильность», «профессиональная компетентность» учителя сельской школы; рассматривают профессиональную компетенцию учителя как компонент профессиональной мобильности и определяют условия организации образовательного процесса, направленного на повышение уровня профессиональной компетентности и мобильности учителя.Область применения результатов. Результаты исследования могут быть применены в сфере переподготовки и повышения квалификации учителей основной и средней общеобразовательной школы.
МЕТОДОЛОГИЯ СТРАТЕГИЧЕСКОГО УПРАВЛЕНИЯ СПОРТОМ ВЫСШИХ ДОСТИЖЕНИЙ И ДРУГИМИ ЭЛЕМЕНТАМИ ПОЛИТИКИ МЯГКОЙ СИЛЫ (В КОНТЕКСТЕ ИДЕОЛОГО-СПОРТИВНОЙ И ИДЕОЛОГО-ОБРАЗОВАТЕЛЬНОЙ ЛОГИСТИК)
Authors: Zhitnov Evgeny Aleksandrovich
Published: February 2018

Цель. Исследовать возможности применения квалиметрической модели оценки структурного рейтинга мягкой силы по двум составляющим индекса: индекс спортивного влияния и индекс влияния: образования, языка, экономики. Данная модель позволяет оценивать государства по количественным и качественным характеристикам, опираясь на балльно-рейтинговую форму, основанную на интегральных параметрах.Метод или методология проведения работы. Основу исследования составляют спортивно-образовательные теории и концепции. Данное исследование потребовало включить целый ряд оценочных подходов с включением инструментария педагогики, политологии, экономики, спорта и др.Результаты. Результаты работы заключаются в том, что автор сделал попытку создать интегральную модель оценки уровня рейтинга мягкой силы, основанной на широком диапазоне различных информативных данных, включающих различные показатели.Область применения результатов. Результаты исследования могут быть использованы в педагогической, спортивной, политической деятельностях, где требуется оценить уровень развития государства как в отдельном, так и интегральных аспектах.
Home parenteral nutrition for patients with intestinal failure due to advanced cancer
Authors: Murray Krista , Mehta Shameer
Published: February 2018

Patients who experience intestinal failure as a result of advanced malignancy can be supported with parenteral nutrition in their own home (HPN). This article describes how to identify which cancer patients would benefit from this therapy and how to ensure it is safely and correctly administered in the home setting.
Ocorrência de Myxobolus sp. (MYXOZOA) em Thoracocharax stellatus (KNER, 1858) (CHARACIFORMES) em um Igarapé da Floresta Amazônica, Pará, Brasil
Authors: Araújo Rebeca Silva de , Corrêa Fabiano , Sousa Fabrício Barros de , Ramos Ana Beatriz Mendes Amaral , Sindeaux Neto José Ledamir , Matos Edilson Rodrigues
Published: February 2018

Thoracocharax stellatus (KNER, 1858), pertencente a famíliaGasteropelecidae, é representada por peixes de pequeno porte, com grande importância econômica, pois é uma das 725 espécies de peixes nativos permitidos para explotação com finalidade ornamental.Os peixes foramcapturados com auxílio de tarrafas em uma área adjacente do Rio Guamá, com o comprimento total médio de 4,2±0,8 cm e peso total médio de 0,9±0,3 g.Fragmentosde brânquias foram coletadose analisados a fresco em microscópio de luz, onde foram observados a presença de cistos repletos de esporos de Myxobolus sp. com capsulas polares desiguais. Este estudorelatacomo primeiro registro ascaracterísticasmorfológicas de Myxobolus sp.encontradoem T. stellatus, provenientesde um rio tropical, Amazônia.Palavras-chave: Água doce, peixe ornamental, microparasitos.
Entry into motherhood during adolescence in France
Authors: Tomkinson John , Breton Didier , Mazuy Magali
Published: February 2018

Résumé

En France métropolitaine, le niveau de fécondité des adolescentes (femmes de 18 ans et moins) varie d’une région à une autre. Cet article montre d’abord que les différences régionales ne résistent pas à une standardisation par des caractéristiques sociodémographiques de la population des adolescentes. L’autre résultat important est la mise en évidence de quatre profils de mères adolescentes, profils inégalement répartis dans les régions métropolitaines.

Abstract

In mainland France and Corsica, the level of teenage fertility (of women aged 18 and less) varies from one region to another. This article shows that these regional differences do not remain once standardizing for the sociodemographic characteristics of the female teenage population. The article then highlights from profiles of teenage mothers which are unequally distributed amongst the French regions.
Poem on Atmospheric Phenomena
Authors: Stewart Arthur J
Published: February 2018

A "science-flavored" poem about atmospheric phenomena is offered as a literacy-rich reading activity for all learners.
How Scientists are Portrayed in NSTA Recommends Books
Authors: Finson Kevin D. , Farland-Smith Donna , Arquette Cecile
Published: February 2018

If you use trade books or picture books in your science teaching, how do you choose which books to use with your students? How important is that decision? Do you rely on someone else to evaluate the books so you are assured of their appropriateness and quality? We used the Draw-A-Scientist Test Checklist to examine the illustrations, images, or photographs of scientists portrayed in picture books promoted for use in elementary and middle school classrooms by the National Science Teachers Association in their NSTA Recommends book lists for the last three years. Results revealed that there was much consistency in how scientists were portrayed in the books across the three years, but there were also issues with appropriate numbers of representations of minorities, women, and age of scientists.
Zirconium in the Nuclear Industry: 18th International Symposium
Authors: Comstock Robert J. , Motta Arthur T.
Published: February 2018

Description

Get 43 papers from global researchers on advancements in zirconium technology in the nuclear industry.

Learn more about the range of challenges for the nuclear community and how they are being addressed in top research presented by industry associates, national laboratories, and universities.

This publication includes three papers from the 2013, 2014, and 2015 recipients of the William J. Kroll Zirconium Medal. The Kroll Award recognizes outstanding achievement in the scientific, technological or commercial aspects of zirconium production and utilization.

Topics featured

Special focus areas include waterside corrosion of cladding; accident tolerant fuel cladding; the influence of irradiation on corrosion; characterization of the evolving microstructure at the oxide-metal interface; characterization of oxides formed on E110 and E635 in VVER-1000 reactors; dimensional stability of zirconium alloy components through creep and growth during service; high-temperature behavior of cladding; and accident-tolerant fuel.

These papers were presented at the 18th International Symposium on Zirconium in the Nuclear Industry, sponsored by ASTM International Committee B10 on Reactive and Refractory Metals and Alloys. It took place May 15-19, 2016, in Hilton Head, South Carolina._x000D_
In-Pile Testing of CrN, TiAlN, and AlCrN Coatings on Zircaloy Cladding in the Halden Reactor
Authors: Van Nieuwenhove Rudi , Andersson Vendi , Balak Juraj , Oberländer Barbara
Published: February 2018

There is growing interest among nuclear power utilities to increase power output and to maximize electricity production. In order to deal with these more challenging conditions, new alloys have been developed. Another approach is to apply protective coatings on existing cladding zirconium alloys. Although the coatings described herein were developed in order to improve the corrosion behavior under normal conditions, it is clear that these coatings can also be applied to other materials (iron-chromium-aluminum, molybdenum, silicon carbide) presently being studied for accident-tolerant fuel. In 2011, several commercially available coatings applied by physical vapor deposition were proposed to improve the performance of existing cladding materials. Since then, these coatings have been investigated in out-pile and in-pile experiments at the Halden Reactor Project from 2011 to 2014. Boiling and pressurized water reactor (PWR) in-pile experiments were performed on small cylindrical Inconel 600 and Zircaloy-4 samples with CrN, TiAlN, and ZrO2 coatings. In all cases examined, the CrN coating came out as superior and remained completely intact after the irradiation, as evidenced by SEM analysis. Based on these promising results, an in-pile experiment with coated Zircaloy claddings (containing fuel) was performed in the Halden reactor in PWR conditions in 2014. The experimental rig contained four Zircaloy-4-clad fuel rods—three coated (CrN, TiAlN, and AlCrN) and one uncoated. Due to a mechanical deformation of tubes for cooling water within the rig, the fuel rods were insufficiently cooled, resulting in a higher-than-normal cladding temperature. Nevertheless, an SEM examination showed that the CrN coating largely remained intact apart from several local spots where the coating had cracked or disappeared. Underneath the cracked coating, oxide formation was observed in the Zircaloy-4 cladding. The TiAlN and AlCrN coatings both disappeared after the irradiation.
The Role of Gamma Radiation on Zircaloy-4 Corrosion
Authors: Rishel Douglas M. , Kammenzind Bruce F.
Published: February 2018

A key microstructural feature of irradiated oxide films that form on Zircaloy-4 is the development of significant amounts of interconnected porosity or microcracking, particularly along oxide grain boundaries. This development disrupts the protective nature of the barrier layer, effectively resulting in an increase in the observed post-transition corrosion rates. This observation suggests that some aspect of oxide dissolution may be occurring. It is noteworthy that when exposed to photons with energies greater than that of the oxide band gap, n-type semiconducting oxides are prone to dissolution. Because zirconia (ZrO2) is an n-type semiconductor, it is plausible that high-energy photons may play an important role in corrosion. In an operating nuclear reactor, neutron and gamma flux levels are closely interrelated because they arise, for the most part, from the same originating process (i.e., the fissioning of nuclear fuel). Thus, it is difficult to isolate the independent effects of neutron and gamma radiation on corrosion. It is, however, theoretically conceivable to assess the role that gamma radiation may have on corrosion by comparing instances where variations in radiation environment exists; specifically by comparing where variations in gamma flux levels relative to neutron flux levels within different regions of a reactor or from reactor to reactor exist. Comparisons of the corrosion rates obtained between two different reactors (the Halden test reactor and the advanced test reactor [ATR]) that have differing gamma-to-neutron ratios were performed. In addition, an examination of corrosion rate data from the ATR, in which a variation in gamma-to-neutron flux ratio exists, was also conducted. Results are presented, from both assessments, which indicate that gamma radiation plays a role in the irradiated corrosion behavior of Zircaloy-4. In addition to a discussion of experimental data, potential mechanisms associated with photon-induced oxide dissolution of n-type semiconducting oxides, such as zirconia, is also provided.
High-Temperature Secondary Hydriding Experiments with E110 and E110G Claddings
Authors: Hózer Zoltán , Nagy Imre , Vimi András , Kunstár Mihály , Szabó Péter , Novotny Tamás , Perez-Feró Erzsébet , Kis Zoltán , Szentmiklósi László , Horváth Márta , Csordás Anna Pintér , Barsy Eszter , Kulacsy Katalin , Grosse Mirco
Published: February 2018

Secondary hydriding can take place during a loss-of-coolant accident event after the ballooning and burst of the zirconium alloy cladding. The oxidation and hydrogen uptake in the ballooned section can produce the weakest segment of the rod. This phenomenon was investigated in the past mainly for Zircaloy-4 cladding. We investigated the effect of secondary hydriding in VVER reactors with E110 and E110G alloys. A high-temperature facility was built to carry out high-temperature treatment of fuel cladding samples. The burst of tubes was reached with inner pressurization at 750 and 800°C. After burst the samples were oxidized in the same furnace for different periods and at different temperatures. The oxidized samples were tested in a tensile test machine with four-point bending tests. The microstructure of the samples was analyzed by optical and scanning electron microscopy. The hydrogen content of the cladding was measured by heat extraction, prompt gamma activation analyses, and neutron radiography methods. The experiments indicated that the ballooned section after oxidation became the weakest segment of the VVER fuel. According to the mechanical testing, the cladding samples were brittle even after a short oxidation time (200 s at 1,000°C) without any sign of ductile behavior. The comparison of E110 and E110G samples showed that the E110 tubes lost their load-bearing capability or even integrity much earlier than the E110G samples treated under similar conditions.
Combined Raman Imaging and 18O Tracer Analysis for the Study of Zircaloy-4 High-Temperature Oxidation in Spent Fuel Pool Accident
Authors: Kasperski Anne , Duriez Christian , Mermoux Michel
Published: February 2018

Oxidation at high temperature (HT) of cladding materials is expected to be the primary cause of the fuel assemblies' degradation in spent fuel storage pool loss of cooling accidents. Unlike a loss-of-coolant accident (LOCA) in a reactor vessel, the presence of air in the atmosphere is expected in a spent fuel pool accident and is known to be an aggravating factor because of the “catalytic” role of nitrogen on the oxidation. In steam LOCA conditions, a low-temperature (LT) oxidation scale simulating the corrosion oxide formed during in-service use of the assemblies has been observed to have a protective effect regarding subsequent HT oxidation. In the presence of nitrogen, HT oxidation kinetic experiments show that the protective effect of an LT corrosion scale also exists but is lost much earlier than in pure steam. Oxygen transport through LT oxide layers has been studied using the 18O tracer technique. We performed experiments in 18O2 alone as well as in mixed 18O2 + N2 atmospheres, at 850°C. Micro-Raman imaging, both at the specimen surfaces and on cross sections, gave clear evidence for different characteristic distributions of 18O in the scales. Some of these distributions have been correlated with the presence of cracks and porosity in the LT oxide, which allows oxygen to locally penetrate in the scales. In cases in which no radial crack is present, apparent oxygen diffusion coefficients in the oxide were derived from fitting 18O diffusion profiles. Nitrogen appears to have no or only a limited influence on the oxygen diffusivity, but it is observed to reach the metal-oxide interface faster than oxygen, at which point it reacts with the metal and the sub-stoichiometric oxide to form zirconium nitride. The later conversion of the ZrN into ZrO2 might lead to the destabilization of the LT scale and to the loss of its protective effect.
Out-of-Reactor Test of Corrosion and Hydrogen Pickup in Fuel Cladding Materials in Contact with Nickel Metal
Authors: Wells Daniel M. , Becker Richard , Chen Jiaxin , Anghel Clara , Hussey Dennis , Iyer Jayashri , Stevens Jacqueline
Published: February 2018

Increased reactor coolant hydrogen concentration in pressurized water reactors (PWRs) is under consideration for potential benefits in reducing primary water stress corrosion cracking (PWSCC) crack growth rate as well as increasing PWSCC crack initiation time in nickel-based alloys. Potential concerns related to fuel performance include possible increases in hydrogen pickup (HPU) by zirconium-based alloys and the enhancement of the pickup through the so-called nickel-window effect. Although the risk of this occurrence may be low, the consequences of increased HPU could be substantial. We examined the impact of dissolved hydrogen (DH) concentrations on Zircaloy-4 corrosion and HPU when the samples are in contact with nickel sources. The work was completed in conjunction with a large project that evaluated the impact of dissolved hydrogen on various fuel cladding and spacer weld specimens of M5®, ZIRLO®, Optimized ZIRLO™, Low-Tin ZIRLO™, Optimized Low-Tin Zircaloy-4, and Zircaloy-2 in either as-received or pre-oxidized conditions for exposures up to 730 days in high-pressure, out-of-reactor autoclave systems operating with a simulated PWR coolant at three different DH concentrations: 30, 100, and 500 cm3 (cc) H2/kg H2O. A significant increase in HPU was observed for some Zircaloy-4 specimens in contact with synthetic crud at elevated DH levels. The HPU increased with increasing DH and a metallic nickel fraction in the synthetic crud. The formation of metallic nickel in the synthetic crud samples at elevated DH levels was confirmed.
Effect of Alloying Elements, Cold Work, and Hydrogen on the Irradiation-Induced Growth Behavior of Zirconium Alloy Variants
Authors: Yagnik Suresh , Adamson Ronald , Kobylyansky Gennady , Chen Jen-Hung , Gilbon Didier , Ishimoto Shinji , Fukuda Takuji , Hallstadius Lars , Obukhov Alexander , Mahmood Sheikh
Published: February 2018

In-reactor dimensional changes in zirconium-based alloys result from a complex interplay of many factors, such as (1) alloy type and composition, including the addition of elements such as niobium, iron, and tin; (2) fabrication process, including cold work, texture, and residual stresses; (3) irradiation temperature; and (4) hydrogen levels. In many cases, the observed dimensional changes in light water reactor fuel-assembly components—especially at high exposures—cannot be fully explained based on current growth and creep models. Therefore, a systematic approach was taken in this multiyear (2005–2011) Nuclear Fuel Industry Research Program investigation. The objective was to measure stress-free irradiation-induced growth (IIG) of specially fabricated alloys through irradiation under controlled conditions in the BOR-60 fast-flux test reactor up to a high fluence of approximately 2 × 1026 m−2 (E > 1 MeV)—equivalent to maximum of approximately 37 dpa exposure—followed by postirradiation examinations (PIEs). Irradiation temperature was within a narrow temperature range (320 ± 10°C). The PIEs included dimensional-change and microhardness measurements, metallography and hydride etching, and scanning transmission electron microscopy (STEM) or transmission electron microscopy (TEM).

All irradiation samples (typically flat rectangular coupons or curvilinear cutouts of cladding tubes sized 35 by 6.5 by 0.8 mm) were prefilmed to avoid the uptake of impurity hydrogen from sodium-cooled BOR-60. A wide variety of samples representing standard LWR cladding alloys with and without prehydriding (approximately 116 to approximately 718 ppm) as well as special compositions with iron contents (100 to 4,000 ppm) were irradiated. The irradiation in BOR-60 was done in five different stages (eight microcycles) and lasted approximately 18 months with interim and final growth measurements made using a high precision-length measurement device. Results of the extensive investigation include: significant effects of Fe, Nb, and hydrogen additions; quantification of growth rates from low to very high fluences (dpas); measurement of volume changes; and correlation of growth with -component dislocation densities.
In Situ Investigations of the Hydrogen Uptake of Zirconium Alloys during Steam Oxidation
Authors: Grosse Mirco , Steinbrueck Martin , Schillinger Burkhard , Kaestner Anders
Published: February 2018

The hydrogen uptake during steam oxidation of Zircaloy-4 and E110 was investigated in situ in the temperature range of 1,000–1,300°C. The procedure to determine hydrogen concentrations from the neutron radiographs measured is explained in detail. Very fast hydrogen absorption (less than 10 s) was observed directly after starting the steam injection. The maximal hydrogen concentration reached increased with increasing temperatures. A slight release of hydrogen was observed after this first fast hydrogen uptake. The hydrogen concentration depended on time with a power of −1/8. An enhanced hydrogen uptake occurred if the oxidation switched into the breakaway mode. The hydrogen concentration increased by nearly one order of magnitude.
Hydride Reorientation in Zircaloy-4 under Different States of Stress as Studied with In Situ X-Ray Diffraction
Authors: Cinbiz M. Nedim , Motta Arthur T. , Koss Donald , Billone Michael
Published: February 2018

Hydride reorientation can occur as a result of vacuum drying or transportation of spent nuclear fuel rods prior to dry cask storage. The elevated temperatures generate high internal gas pressure in the fuel rods, causing δ-hydride platelets to precipitate perpendicular to the hoop stress during cooling. Because the loading causes multiaxial stresses, it is of interest to elucidate the role of stress state on the threshold stress for hydride reorientation. To that end, specially designed specimens were used with a range of stress biaxiality ratios (σ1/σ2) from uniaxial tension (σ1/σ2 = 0) to near-equibiaxial tension (σ1/σ2 = 0.8). The threshold stress was determined in each case by matching the major and minor stresses (and thus the local stress state) calculated by finite-element analysis to the hydride microstructures created by the thermomechanical treatment at that specific location. Using cold-worked stress-relieved Zircaloy-4, the results show that as the stress biaxiality ratio increased from uniaxial tension to near-equibiaxial tension, the threshold stress decreased from 155 to 75 MPa. To elucidate the hydride reorientation process, hydride precipitation and d-spacing behavior were investigated in situ using synchrotron radiation diffraction. The precipitation temperature for out-of-plane hydrides was lower than that for in-plane hydrides. The δ{111} d-spacing aligned with the hydride platelet face was greater than the d-spacing of planes aligned with platelet edges. Furthermore, δ{111} planes exhibited bilinear thermally induced expansion, but only for those planes aligned with hydride plate edges. In contrast, the hydride platelet face contracted upon heating. The experimental results were explained by a reversal of stress state associated with precipitating or dissolving hydrides within α-zirconium. In addition, irradiated cladding after thermomechanical treatments was examined by synchrotron radiation diffraction at ambient temperatures. Although the hydride intensity was low for accurately determining d-spacing, the diffraction patterns indicated that β-niobium peaks present in the un-irradiated cladding were diminished after irradiation.
Hydrogen Pickup Mechanism in Zirconium Alloys
Authors: Couet Adrien , Motta Arthur T. , Ambard Antoine , Comstock Robert J.
Published: February 2018

Because hydrogen ingress into zirconium cladding can cause embrittlement and limit cladding lifetime, hydrogen pickup during corrosion is a critical life-limiting degradation mechanism for nuclear fuel. However, mechanistic knowledge of the oxidation and hydrogen pickup mechanisms is still lacking. In an effort to develop such knowledge, we conducted a comprehensive study that included detailed experiments combined with oxidation modeling. We review this set of results conducted on zirconium alloys herein and articulate them into a unified corrosion theoretical framework. First, the hydrogen pickup fraction (fH) was accurately measured for a specific set of alloys specially designed to determine the effects of alloying elements, microstructure, and corrosion kinetics on fH. We observed that fH was not constant and increased until the kinetic transition and decreased at the transition. fH depended on the alloy and was lower for niobium-containing alloys. These results led us to hypothesize that hydrogen pickup during corrosion results from the need to balance the charge during the corrosion reaction such that fH decreases when the rate of electron transport through the protective oxide increases. To assess this hypothesis, two experiments were performed: (1) micro-X-ray absorption near-edge spectroscopy (μ-XANES) to investigate the evolution of the oxidation state of alloying elements when incorporated in the growing oxide and (2) in situ electrochemical impedance spectroscopy (EIS) to measure oxide resistivity as a function of exposure time on different alloys. With the use of these results, we developed an analytical zirconium alloy corrosion model based on the coupling of oxygen vacancies and electron currents. Both modeling and EIS results show that as the oxide electric conductivity decreases the fH increases. These new results support the general hypothesis of charge balance. The model quantitatively and qualitatively predicts the differences observed in oxidation kinetics and hydrogen pickup fraction between different alloys.