bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal associations between morningness/eveningness, problematic social media use, psychological distress and daytime sleepiness: Mediated roles of sleep quality and insomnia among young adults
Authors: Lin Chung‐Ying , Imani Vida , Griffiths Mark D. , Broström Anders , Nygårdh Annette , Demetrovics Zsolt , Pakpour Amir H.
Published: May 2020

The extant literature has suggested relationships between an individual's chronotype (in relation to morningness/eveningness) and several outcomes, including addictive disorders, psychological distress and daytime sleepiness. Moreover, sleep quality has been proposed to be a mediator in the aforementioned relationships. Consequently, the aim of the present study was to investigate the complex relationship between morningness/eveningness, problematic social media use, psychological distress and daytime sleepiness, with the potential mediators of sleep quality and insomnia. All participants (N = 1,791 [30.1% males]; mean age = 27.2 years,SD = 10.1) completed a battery of psychometric scales, including a reduced version of the Morningness‐Eveningness Questionnaire (at baseline), the Pittsburgh Sleep Quality Index and Insomnia Severity Index (1 month after baseline assessment), the Bergen Social Media Addiction Scale, the Hospital Anxiety and Depression Scale, and the Epworth Sleepiness Scale (2 months after baseline assessment). The impacts of morningness‐eveningness on problematic social media use, anxiety, depression and daytime sleepiness were found in the mediation models. Furthermore, the mediated effects of insomnia and sleep quality were observed. The present study's results emphasize the importance of promoting healthy sleep habits and sleep hygiene behaviours, and that of early detection of sleep problems among individuals who have the eveningness chronotype, because this would significantly improve their health outcomes.
Workplace‐based assessments in postgraduate medical education: A hermeneutic review
Authors: Prentice Shaun , Benson Jill , Kirkpatrick Emily , Schuwirth Lambert
Published: May 2020

Objectives

Since their introduction, workplace‐based assessments (WBAs) have proliferated throughout postgraduate medical education. Previous reviews have identified mixed findings regarding WBAs' effectiveness, but have not considered the importance of user‐tool‐context interactions. The present review was conducted to address this gap by generating a thematic overview of factors important to the acceptability, effectiveness and utility of WBAs in postgraduate medical education.

Method

This review utilised a hermeneutic cycle for analysis of the literature. Four databases were searched to identify articles pertaining to WBAs in postgraduate medical education from the United Kingdom, Canada, Australia, New Zealand, the Netherlands and Scandinavian countries. Over the course of three rounds, 30 published articles were thematically analysed in an iterative fashion to deeply engage with the literature in order to answer three scoping questions concerning acceptability, effectiveness and assessment training. As each round was coded, themes were refined and questions added until saturation was reached.

Results

Stakeholders value WBAs for permitting assessment of trainees' performance in an authentic context. Negative perceptions of WBAs stem from misuse due to low assessment literacy, disagreement with definitions and frameworks, and inadequate summative use of WBAs. Effectiveness is influenced by user (eg, engagement and assessment literacy) and tool attributes (eg, definitions and scales), but most fundamentally by user‐tool‐context interactions, particularly trainee‐assessor relationships. Assessors’ assessment literacy must be combined with cultural and administrative factors in organisations and the broader medical discipline.

Conclusions

The pivotal determinants of WBAs' effectiveness and utility are the user‐tool‐context interactions. From the identified themes, we present 12 lessons learned regarding users, tools and contexts to maximise WBA utility, including the separation of formative and summative WBA assessors, use of maximally useful scales, and instituting measures to reduce competitive demands.
Evolutionary adaptations in four hippoboscid fly species belonging to three different subfamilies
Authors: Andreani A. , Sacchetti P. , Belcari A.
Published: May 2020

Lipoptena cervi (Linnaeus, 1758), Lipoptena fortisetosa Maa, 1965, Hippobosca equina Linnaeus, 1758, and Pseudolynchia canariensis (Macquart, 1840) (Diptera: Hippoboscidae) are haematophagous ectoparasites that infest different mammal and bird species and occasionally attack humans. They are known for the health implications they have as vectors of pathogens to humans and animals, and for the injuries they inflict on their host's skin. This study focused on the morphological structures evolved by parasites in terms of their biology and the different environment types that they inhabit. To this aim, we examined four hippoboscid species, as well as their hosts' fur (ungulate and horse), and feather (pigeon) through light and Scanning Electron Microscopy (SEM) observations in order to highlight the main morphological features that evolved differently in these flies and to explain the effect of hosts' fur/feather microhabitats on the morphological specializations observed in the investigated ectoparasites. The studied species showed main convergent characters in mouthparts while remarkable differences have been detected on the antennal sensillar pattern as well as on the leg acropod that displayed divergent characters evolved in relation to the
host.
Prevention of occupational injuries and accidents: A social capital perspective
Authors: Hafeez Hira , Abdullah Muhammad Ibrahim , Riaz Amir , Shafique Imran
Published: May 2020

Prior research has consistently established the pragmatic nature of literature regarding occupational injuries and accidental happenings faced by nursing professionals. However, current realities require a subjective approach to identify preventative measures that could influence occupational health and safety in healthcare sectors. A qualitative design followed a descriptive approach to assess unbiased opinions towards occupational obstructions that lead to accidental happenings. This study used the social capital framework in particular as a support resource to eliminate its detrimental effects on nurse's capacity to serve their patients. The findings extended the fundamental understanding of social capital from social ties to workplace and personal ties as potential mechanisms of support. Healthcare organizations need to redefine their control policies to provide the ultimate support to their care agents. A social capital model offers nursing practitioners and nursing managers an approach for building evidence‐based policies with implications for nurse's safety, education and training.
Jackhammer esophagus: A meta‐analysis of patient demographics, disease presentation, high‐resolution manometry data, and treatment outcomes
Authors: Wahba George , Bouin Mickael
Published: May 2020

Background

Jackhammer esophagus (JE) is a newly described esophageal motility disorder. However, there are limited data on JE and this entity remains misunderstood.

Methods

We performed a systematic review of clinical series on JE through MEDLINE, EMBASE, and Web of Science. Data from included studies were then extracted, and random‐effects meta‐analyses were performed.

Results

Thirty‐eight studies met inclusion criteria. The pooled prevalence of JE was 1.97% [95% CI: 1.39%‐2.78%] among patients referred for high‐resolution manometry (HRM). The mean age at diagnosis was 60.8 years [95% CI: 57.1‐64.4] and 65% [95% CI: 58%‐72%] of patients were female. JE was significantly more prevalent in postlung transplant patients and morbidly obese patients undergoing HRM (23.99% [95% CI: 9.00%‐38.97%] and 5.18% [95% CI: 1.76%‐14.3%] respectively). Dysphagia was the most common presentation of JE (64% [95% CI: 52%‐77%]) followed by gastroesophageal reflux disease (46% [95% CI: 26%‐67%]). The pooled mean distal contractile integral (DCI) of all standard HRM swallows was 9249 mm Hg·s·cm [95% CI: 7834‐10 663], and the pooled mean integrated relaxation pressure (IRP) was 13.9 mm Hg [95% CI: 8.2‐19.7]. Overall, 73.6% [95% CI: 64.0%‐83.1%] of JE patients who underwent treatment achieved clinical symptom improvement (79% [95% CI: 74%‐85%] for endoscopic treatment and 63% [95% CI: 47%‐79%] for medical treatment). The pooled clinical success rate of peroral endoscopic myotomy (POEM) specifically was 82% [95% CI: 75%‐90%].

Conclusions

JE is a new motility disorder most commonly presenting with dysphagia. High clinical suspicion is important because the diagnosis can only be made through HRM.
Mutation of HPR1 encoding a component of the THO/TREX complex reduces STOP1 accumulation and aluminium resistance in Arabidopsis thaliana
Authors: Guo Jinliang , Zhang Yang , Gao Huiling , Li Shengben , Wang Zhen‐Yu , Huang Chao‐Feng
Published: May 2020

C2H2‐type zinc finger transcription factor sensitive to proton rhizotoxicity 1 (STOP1) plays an essential role in aluminium (Al) resistance in Arabidopsis thaliana by controlling the expression of a set of Al‐resistance genes, including the malate transporter‐encoding gene A. thaliana aluminium activated malate transporter 1 (AtALMT1) that is critically required for Al resistance. STOP1 is suggested to be modulated by Al at post‐transcriptional and/or post‐translational levels. However, the underlying molecular mechanisms remain to be demonstrated.

We carried out a forward genetic screen on an ethyl methanesulphonate mutagenized population, which contains the AtALMT1 promoter‐driven luciferase reporter gene (pAtALMT1:LUC), and identified hyperrecombination protein 1 (HPR1), which encodes a subunit of the THO/TREX complex. We investigate the effect of hpr1 mutations on the expression of Al‐resistance genes and Al resistance, and we also examined the regulatory role of HPR1 in nuclear messenger RNA (mRNA) and protein accumulation of STOP1 gene.

Mutation of HPR1 reduces the expression of STOP1‐regulated genes and the associated Al resistance. The hpr1 mutations increase STOP1 mRNA retention in the nucleus and consequently decrease STOP1 protein abundance. Mutation of regulation of AtALMT1 expression 1 (RAE1) that mediates STOP1 degradation in the hpr1 mutant background can partially rescue the deficient phenotypes of hpr1 mutants.

Our results demonstrate that HPR1 modulates Al resistance partly through the regulation of nucleocytoplasmic STOP1 mRNA export.
Neighbourhood residential density and childhood obesity
Authors: Zou Yuxuan , Ma Yanan , Wu Zhifeng , Liu Yang , Xu Min , Qiu Ge , Vos Heleen , Jia Peng , Wang Limin
Published: May 2020

Residential density is considered an important attribute of the built environment that may be relevant to childhood obesity. However, findings remain inconclusive, and there are no reviews yet on the association between residential density and childhood obesity. This study aimed to systematically review the associations between residential density and weight‐related behaviours and outcomes. A comprehensive literature search was conducted using the Cochrane Library, PubMed and Web of Science for articles published before 1 January 2019. A total of 35 studies conducted in 14 countries were identified, including 33 cross‐sectional studies, one longitudinal study and one containing both study designs. Residential density was measured by Geographic Information Systems in 28 studies within a varied radius from 0.25 to 2 km around the individual residence. Our study found a general positive association between residential density and physical activity (PA); no significant associations were observed. This study provided evidence for a supportive role of residential density in promoting PA among children. However, it remained difficult to draw a conclusion between residential density and childhood obesity. Future longitudinal studies are warranted to confirm this association.
To compare the effect of ice and the lignocaine gel in reducing pain of needle prick before palatal nerve block
Authors: Kumari K. , Kaur G. , Arora S.S. , Pandher P.K. , Singh R. , Bhat R.A.
Published: May 2020

Aim

The purpose of this study was to compare the effect of ice and the lignocaine gel in reducing pain of needle prick before palatal nerve block using Numerical Rating Scale (NRS) and sound, eye and motor (SEM) scale.

Material and Methodology

In this split‐mouth design study, a total of 200 patients undergoing maxillary molar extraction were selected and were randomly divided into two equal groups having 200 sites in each group. The operative sites were divided into two groups, namely, Group A in which Lignocaine gel was applied and Group B in which ice was applied.

Results

Among the participant, 138 were men and 62 were women whose age ranged from 18 to 60 years. Statistical analysis of pain on Numerical Rating Scale (NRS) showed that the mean of NRS score for the group A and group B as 0.2 ± 0.41 and 0.05 ± 0.226 (mean ± SD), respectively, which was statistically insignificant (P >0.05). Mean of sound in SEM scale for the group A and group B as 1.4 ± 0.4894 and 1.05 ± 0.2236 (mean ± SD), respectively, which was statistically insignificant (P >0.05). Statistical evaluation showed that mean of eye in SEM scale for the group A and group B was 1.05 ± 0.2236 and 1.15 ± 0.3663 (mean ± SD), respectively, which was also statistically insignificant (P >0.05). Mean of motor scale for the group A and group B was 1.05 ± 0.2236 and 1.15 ± 0.3663 (mean ± SD), respectively, which was statistically insignificant (P >0.05).

Conclusion

Ice has shown equal efficacy in reducing pain of needle prick compared to lignocaine gel. Thus, ice can be proved to be a cost‐effective alternative.
Embolization of congenital portosystemic shunt presenting after pediatric liver transplantation: Case report and literature review
Authors: Rohringer Taryn J. , Ng Vicky L. , Amaral Joao G. , Parra Dimitri A.
Published: May 2020

This case report describes a 13‐year 10‐month‐old girl who underwent a deceased‐donor split LT for primary diagnosis of biliary atresia at the age of 12 months, who presented with a lower GI bleed. Ultrasound and CT revealed a venous vascular anomaly involving the cecum and ascending colon, with communication of the SMV and pelvic veins consistent with a CEPS. Associated varices were noted in the pelvis along the uterus and urinary bladder. These findings were confirmed by trans‐hepatic porto‐venography, which was diagnostic and therapeutic as a successful embolization of the CEPS was performed using micro‐coils. There were no complications following the procedure and no further GI bleeding occurred, illustrating the efficacy of this treatment option for CEPS. We discuss the literature regarding the presenting complaint of GI bleeding post–LT, CEPS as a rare cause of GI bleeding and its association with PV, and the classification and treatment of CEPS.
Effects of temperature on the development and fecundity of Microplitis similis (Hymenoptera: Braconidae), a parasitoid of Spodoptera litura (Lepidoptera: Noctuidae)
Authors: Yi Si‐Jia , Hopkins Richard J. , Chen Xu‐Yang , Chen Zhuang‐Mei , Wang Xing , Huang Guo‐Hua
Published: May 2020

Microplitis similis (Hymenoptera: Braconidae) is a solitary endoparasitoid of Spodoptera litura larvae (Lepidoptera: Noctuidae). Here, the effects of constant temperature (18, 21, 24, 27, 30, 33 and 36 °C) on the development and fecundity of M. similis developing in S. litura were studied in the laboratory to clarify the range of its potential distribution and better understand its potential as a biological control agent. The developmental duration of M. similis varied from 10.6 (33 °C) to 27.9 days (18 °C). The developmental threshold temperature and effective accumulative temperature of M. similis were 9.96 °C and 231.14 Degree‐days, respectively. The average adult longevity of M. similis ranged from 5.1 (33 °C) to 26.8 days (18 °C). The maximum fecundity of the parasitoid was observed at 27 and 30 °C, which were 43.07 and 39.73 eggs, respectively. The minimum fecundity of the parasitoid was observed at 18 °C, which was 8.27 eggs. The intrinsic rate of increase (rm) and finite rate of increase (λ) of M. similis were the highest at 30 °C. The net reproduction rate (R0) was the highest at 27 °C and 30 °C, which were 44.34 and 40.39, respectively. We concluded that temperatures in the range 27–30 °C are the most suitable for development and reproduction of M. similis. Our study provides detailed basic information for development and reproduction of M. similis under different temperature conditions.
Prevalence of Phytophthora species in macadamia orchards in Australia and their ability to cause stem canker
Authors: Jeff‐Ego Olumide S. , Drenth Andre , Topp Bruce , Henderson Juliane , Akinsanmi Olufemi A.
Published: May 2020

In Australia, Phytophthora cinnamomi is the only species reported as the causal agent of stem canker and root rot in macadamia. In other countries, five Phytophthora species have been reported to cause diseases in macadamia, which led us to question if more than one Phytophthora species is responsible for poor tree health in macadamia orchards in Australia. To investigate this, samples were collected from the rhizosphere, stem, and root tissues of trees with and without symptoms, nurseries, and water sources from 70 commercial macadamia orchards in Australia. Phytophthora isolates were identified based on morphological characteristics and DNA sequencing. P. cinnamomi was the most predominant and widely distributed species, and was obtained from the different types of samples including symptomless root tissues. In addition to P. cinnamomi, only P. multivora was isolated from diseased tissue (stem canker) samples. Six other Phytophthora species were obtained from the rhizosphere samples: P. pseudocryptogea, P. citrophthora, P. nicotianae, P. gondwanense, P. sojae, and a new Phytophthora taxon. Only P. cinnamomi was obtained from macadamia nursery samples, while five Phytophthora species were obtained from water sources. Of the heterothallic Phytophthora species, mating type A2 isolates were dominant in P. cinnamomi isolates, whereas only mating type A1 isolates were obtained for P. nicotianae, P. pseudocryptogea, and P. citrophthora. Pathogenicity assays revealed that P. cinnamomi and P. multivora caused significantly larger stem and leaf lesions than P. citrophthora, P. nicotianae, and P. pseudocryptogea. Phytophthora sp. and P. sojae were nonpathogenic towards leaves and stems.
Aetiology of branch dieback, panicle and shoot blight of pistachio associated with fungal trunk pathogens in southern Spain
Authors: López‐Moral Ana , del Carmen Raya María , Ruiz‐Blancas Cristina , Medialdea Ignacio , Lovera María , Arquero Octavio , Trapero Antonio , Agustí‐Brisach Carlos
Published: May 2020

Pistachio represents an emerging nut crop across the Mediterranean basin. In Spain, pistachio has been traditionally cultivated in marginal‐dry areas with unfavourable climatic conditions for plant diseases. Consequently, little attention has been given to research on pistachio diseases until recently. Symptoms of branch dieback and cankers, and shoot and panicle blight have been recently observed in commercial pistachio orchards across southern Spain. In this study, 10 commercial pistachio orchards showing disease symptoms were surveyed between 2017 and 2018. Botryosphaeriaceae fungi were consistently isolated from affected shoots, among other fungal families with minor relevance. Representative isolates of each family were characterized based on colony and conidial morphology, optimum growth temperature, and the comparison of DNA sequence data (ITS, LSU, EF, TUB2, and ACT genomic regions). Detached and attached shoots, and attached panicles of pistachio cv. Kerman were inoculated with mycelial plugs or conidial suspensions to demonstrate the pathogenicity of the selected isolates. Botryosphaeria dothidea, Lasiodiplodia pseudotheobromae, Neofusicoccum mediterraneum, N. parvum, Diaporthe neotheicola, Diaporthe sp., Eutypa lata, Eutypa sp., Cytospora sp., and Phaeoacremonium minimum were identified. P. minimum had the highest optimum growth temperature (29.6 °C) and Cytospora sp. the lowest (21–22 °C). Botryosphaeriaceae isolates showed the largest lesions on inoculated shoots, with L. pseudotheobromae being the most aggressive, followed by Neofusicoccum species. Panicles inoculated with N. mediterraneum showed blight symptoms and canker formation 6 weeks after inoculation, without significant differences in aggressiveness between isolates. This work reports relevant information about this emerging disease in the novel Spanish pistachio‐growing areas.
Parasites and coral‐associated invertebrates that impact coral health
Authors: Barton Jonathan A. , Bourne David G. , Humphrey Craig , Hutson Kate S.
Published: May 2020

Globally coral reefs are in decline, largely driven by local anthropogenic pressures combined with broader cumulative impacts from climate change. Coral aquaculture will play an important role in active reef restoration and attempts to preserve some semblance of coral reefs in highly impacted areas. Achieving maximum growth and survivorship of cultured corals is necessary to achieve optimal results. This is not possible without the study of coral pests and diseases which can be detrimental to coral health. Here we review the complex relationships between corals and their associated symbiotic organisms, identify invertebrates that may harm the corals and suggest known management techniques in captivity. Groups considered included acoels (Xenacoelomorpha: Acoela), digeneans (Trematoda: Digenea), polyclads (Rhabditophora: Polycladida), gastropods (Mollusca: Gastropoda), decapods (Malacostraca: Decapoda), copepods (Hexanauplia: Copepoda) and pyrgomatids (Cirripedia: Pyrgomatidae). There are few empirically validated management techniques for coral pests, particularly in terms of large‐scale aquaculture, emphasizing the need for further directed research in this area. Information generated through the ornamental trade and hobbyists is valuable to inform future research direction targeted towards captive coral husbandry, reef ecosystem management and restoration strategies.
Safe performance of diagnostic bronchoscopy/EBUS during the SARS‐CoV‐2 pandemic
Authors: Steinfort Daniel P. , Herth Felix J.F. , Irving Louis B. , Nguyen Phan T.
Published: May 2020

The SARS‐CoV‐2 pandemic is unprecedented in our professional lives and much effort and resources will be devoted to care of patients (and HCW) affected by this illness. We must also continue to aim for the same standard of care for our non‐COVID respiratory patients, while minimizing risks of infection transmission to our colleagues. This commentary addresses the key paired issues of minimizing performance of diagnostic/staging bronchoscopy in patients with suspected/known lung cancer while maximizing the safety of the procedure with respect to HCW transmission of COVID‐19.
Effect of a water, sanitation and hygiene program on handwashing with soap among household members of diarrhoea patients in healthcare facilities in Bangladesh: a cluster‐randomised controlled trial of the CHoBI7 mobile health program
Authors: Zohura Fatema , Bhuyian Md. Sazzadul Islam , Saxton Ronald E. , Parvin Tahmina , Monira Shirajum , Biswas Shwapon K. , Masud Jahed , Nuzhat Sharika , Papri Nowshin , Hasan M. Tasdik , Thomas Elizabeth D , Sack David , Perin Jamie , Alam Munirul , George Christine Marie
Published: May 2020

Objective

The Cholera‐Hospital‐Based‐Intervention‐for‐7‐days (CHoBI7) is a water treatment and handwashing with soap intervention for diarrhoea patients and their household members which is initially delivered in a healthcare facility setting. This study evaluated the effectiveness of CHoBI7 program delivery in increasing handwashing with soap in a healthcare facility setting among diarrhoea patients and their household members.

Methods

A randomised controlled trial of the CHoBI7 program was conducted among 404 diarrhoea patients and their accompanying household members in healthcare facilities in Dhaka, Bangladesh. The ‘Standard Message’ Arm received the standard message given in Bangladesh to diarrhoea patients on the use of oral rehydration solution. The ‘Health Facility Visit + Soapy Water’ Arm received the standard message, the CHoBI7 communication module delivered bedside to the patient; and a soapy water bottle in the healthcare facility. The ‘Health Facility Visit + Handwashing Station’ Arm received this same intervention plus a small plastic handwashing station. Within 24 h of intervention delivery, three‐hour structured observation of handwashing practices at stool/vomit‐ and food‐related events (key events) was conducted in healthcare facilities of diarrhoea patients and their accompanying household members.

Results

Compared to the Standard Message Arm, there was significantly more handwashing with soap at key events in both the Health Facility Visit + Soapy Water Arm (51% vs. 25 %) (Odds Ratio: 3.02; (95% Confidence Interval (CI): 1.41, 6.45) and the Health Facility Visit + Handwashing Station Arm (58% vs. 25%) OR: 4.12; (95% CI: 1.86, 9.14).

Conclusion

These findings demonstrate that delivery of the CHoBI7 communication module and provision of a soapy water bottle to diarrhoea patients and their accompanying household members presents a promising approach to increase handwashing with soap among this high risk population in a healthcare facility setting in Bangladesh.
Analytical and Experimental Study of Magnetomechanical Properties of Magnetic Porous PDMS Sponge Under Non-Uniform Magnetic Fields
Authors: Shademani Ali , Chiao Mu
Published: May 2020

Magnetic elastomers (MEs) respond to an applied magnetic field through magnetomechanical coupling, where the mechanical properties of the MEs change with magnetic field strength. These phenomena have been mostly studied under homogenous magnetic fields due to the simplicity. In this work, the effects of the magnetic field gradient on the mechanical properties and the response of the MEs was examined. MEs are made by embedding carbonyl iron microparticles (CI) into a polydimethylsiloxane (PDMS) matrix, which is later rendered porous. The influence of the CI concentration was investigated by manipulating four different samples with CI/PDMS weight ratios of 0.2, 0.6, 1.0, and 1.4. An analytical method was proposed to further understand the interactions of the magnetic field gradient and the material’s response. The proposed theory was later verified with experimental results from compression tests in the presence of different magnetic fields. The proposed theoretical framework and experimental methods can be used to improve the design of MEs in the future.
Monitoring and Imaging of Bolted Steel Plate Joints Using Ultrasonic Guided Waves
Authors: Shah Jay Kumar , Mukherjee Abhijit
Published: May 2020

Steel structures with bolted joints are easily dismantled and repurposed. However, maintaining joint integrity is a challenge. This paper reports a non-destructive methodology to monitor steel bolted joints. Piezoelectric ceramic patches have been surface bonded in the joint for transmission and reception of guided ultrasonic waves. Both single and multiple bolted joints have been investigated. It has been demonstrated that the variation in acoustic impedance due at the bolt interface can be discerned and calibrated with bolt torque level. The recorded reflections from interfaces are used as inputs for a newly developed imaging algorithm. The proposed method has the potential to be a reference-free and fully automated method.
Experimental Assessment of a 3D-Printed Stainless Steel Gas Foil Bearing
Authors: Shalash Karim , Schiffmann Jürg
Published: May 2020

Gas foil bearings (GFBs) are a key enabling technology for high-speed turbomachinery. The manufacturing of GFBs relies mainly on sheet metal forming techniques in order to conceive the compliant structure (e.g., bump foil) and the top foil. Such techniques require the development of a special know-how and most importantly, limit the design creativity to what is manufacturable using sheet metal forming. Additive manufacturing (AM) is a disruptive technology in prototyping and fabrication. This paper accesses the feasibility of AM in the fabrication of GFBs using selective laser melting (SLM) technology. A stainless steel GFB is 3D-printed in one piece, including the sleeve, the bump, and top foils. The bearing is assessed geometrically and statically before being tested on a gas bearing test rig, where it supported a ø40 mm rotor (m = 2 kg). The bearing performed similar to a conventional GFB, showing rotordynamically stable and repeatable operation up to 37.5 krpm. Such result highlights the potentials of AM as a viable alternative for foil bearing manufacturing.
Influence of Power on Interplay of Microstructure and Erosion-Tribo Performance of Microwave Composite Clads
Authors: Singh Bhupinder , Zafar Sunny
Published: May 2020

Metal matrix composite (MMC) clads were developed through microwave cladding technique on CA6NM substrate using different microwave power levels. The influence of microwave power was investigated on the microstructure, phase evolution, mechanical properties, and erosion-tribo performance of the clad layers. Increase in microwave power resulted in reduction of Cr7C3 phase in clad layers, which eventually decreases the fracture toughness and microhardness of the clad. Clad fabricated at 600 W exhibited highest fracture toughness (11.6 ± 0.58 MPa√m) and microhardness (949 ± 47.45 HV). All clads exhibited highest erosion at 60 deg indicating a mixed erosion mode. Clads fabricated at power levels beyond 600 W, with less Cr7C3 content exhibited severe carbide pullout, thus deteriorated the slurry erosion resistance of the clads.
A Multi-Layer Perceptron With a Hierarchical Prior for Operating State Recognition of Ship Propulsion Systems
Authors: Zhang Dongdong
Published: May 2020

To define more clearly vibration-related problems of ship propulsion systems, a procedure incorporating operating state recognition into conventional vibration analysis is proposed in this paper. Emphasis is placed on identifying operating modes and decay levels through a multi-layer perceptron (MLP) with a hierarchical prior. First, a variant of stochastic gradient descent (SGD) with momentum is presented for integrating a hierarchical prior into the parameter learning of an MLP network. Then, the MLP network, governing information representation through multiple levels of abstraction is designed, and the hierarchical prior, representing a clear explanation in physics of system operating for an operator or maintainer, is also constructed. Finally, the operating data from a combined diesel or gas turbine (CODOG) system validate that the accuracy improvement of operating state recognition can be achieved by MLP with a hierarchical prior when the sample size is relatively small. Meanwhile, the vibration signals from the CODOG system verify the effectiveness of the vibration analysis procedure coupled with operating state recognition.
Motion Feasibility Framework for Remotely Operated Vehicles Based on Dynamic Positioning Capability
Authors: Ramírez-Macías Juan A. , Vásquez Rafael E. , Sørensen Asgeir J. , Sævik Svein
Published: May 2020

Knowing whether a remotely operated vehicle (ROV) is able to operate at certain foreknown environmental conditions is a question relevant to different actors during the vehicle’s life cycle: during design stages, buying an ROV, planning operations, and performing an operation. This work addresses a framework to assess motion feasibility in ROVs by using the concept of ROV-dynamic positioning capability (ROV-DPCap). Within the proposed framework, the ROV-DPCap number is defined to measure motion capability, and ROV-DPCap plots are used to illustrate results, for quasi-static standard (L2) and site-specific (L2s) conditions, and dynamic standard (L3) and site-specific (L3s) conditions. Data are computed by steady-state or time-domain simulations from the ROV model, depending on the desired analysis. To illustrate the use of the framework, numerical examples for L2 and L2s motion feasibility analyses for NTNU’s ROV Minerva are provided. Motion feasibility can be used to know whether an ROV is appropriately designed for a specific operation and choose the appropriate one for a certain need, for instance, when designing the DP system components or planning an operation from the environmental data and ROV-specific information. As expected, predictions can be improved when more detailed information about the ROV appears; the same framework can be used to provide more detailed answers to motion feasibility-related questions. The results are likely to be straightforwardly understood by people whose work/training is ROV related and can interpret the graphic results for different operation scenarios.
The Transition From Rebound to Bonding in High-Velocity Metallic Microparticle Impacts: Jetting-Associated Power-Law Divergence
Authors: Sun Yuchen , Veysset David , Nelson Keith A. , Schuh Christopher A.
Published: May 2020

A metallic microparticle impacting a metallic substrate with sufficiently high velocity will adhere, assisted by the emergence of jetting—the splash-like extrusion of solid matter at the periphery of the impact. In this work, we compare real-time observations of high-velocity single-microparticle impacts to an elastic–plastic model to develop a more thorough understanding of the transition between the regimes of rebound and bonding. We first extract an effective dynamic yield strength for copper from prior experiments impacting alumina spheres onto copper substrates. We then use this dynamic yield strength to analyze impacts of copper particles on copper substrates. We find that up to moderate impact velocities, impacts and rebound velocities follow a power-law behavior well-predicted on the basis of elastic-perfectly plastic analysis and can be captured well with a single value for the dynamic strength that subsumes many details not explicitly modeled (rate and hardening effects and adiabatic heating). However, the rebound behavior diverges from the power-law at higher impact velocities approaching bonding, where jetting sets on. This divergence is associated with additional lost kinetic energy, which goes into the ejection of the material associated with jetting and into breaking incipient bonds between the particle and substrate. These results further support and develop the idea that jetting facilitates bonding where a critical amount of bond formation is required to effect permanent particle deposition and prevent the particle from rebounding.
Mechanism-Based Energy Regularization in Computational Modeling of Quasibrittle Fracture
Authors: Gorgogianni Anna , Eliáš Jan , Le Jia-Liang
Published: May 2020

Quasibrittle materials are featured by a strain-softening constitutive behavior under many loading scenarios, which could eventually lead to localization instability. It has long been known that strain localization would result in spurious mesh sensitivity in finite element (FE) simulations. Previous studies have shown that, for the case of fully localized damage, the mesh sensitivity can be mitigated through energy regularization of the material constitutive law. However, depending on the loading configuration and structural geometry, quasibrittle structures could exhibit a complex damage process, which involves both localized and diffused damage patterns at different stages of loading. This study presents a generalized energy regularization method that considers the spatial and temporal evolution of damage pattern. The method introduces a localization parameter, which describes the local damage pattern. The localization parameter governs the energy regularization of the constitutive model, which captures the transition from diffused to localized damage during the failure process. The method is cast into an isotropic damage model, and is further extended to rate-dependent behavior. The energy regularization scheme is directly incorporated into the kinetics of damage growth. The model is applied to simulate static and dynamic failures of ceramic specimens. It is shown that the present model is able to effectively mitigate the spurious mesh sensitivity in FE simulations of both types of failure. The present analysis demonstrates the essential role of mechanism-based energy regularization of constitutive relation in FE simulations of quasibrittle fracture.
Si-based materials for lithium-ion batteries I: Surface-modified Si/C powder
Authors: Haasch Richard T. , Abraham Daniel P.
Published: May 2020

X-ray photoelectron spectroscopy was used to analyze Si/C powder obtained from Paraclete Energy, Inc. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure.
Si-based materials for lithium-ion batteries II. Surface-modified Si/C/polyethylene glycol powder
Authors: Haasch Richard T. , Abraham Daniel P.
Published: May 2020

X-ray photoelectron spectroscopy was used to analyze Si/C/polyethylene glycol powder obtained from Paraclete Energy, Inc. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals, with only minor calcium and nitrogen signal, and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure.
Si-based materials for lithium-ion batteries III: Surface-modified Si/C/polyvinylidine difluoride powder
Authors: Haasch Richard T. , Abraham Daniel P.
Published: May 2020

X-ray photoelectron spectroscopy was used to analyze Si/C/polyvinylidine difluoride powder obtained from Paraclete Energy Inc. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with F 1s, O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor nitrogen signal and show the expected silicon-carbon and silicon-fluorine species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure.
Si-based materials for lithium-ion batteries VI. 15% surface-modified Si/C-graphite/carbon black/lithiated polyacrylic acid electrode
Authors: Haasch Richard T. , Abraham Daniel P.
Published: May 2020

X-ray photoelectron spectroscopy was used to analyze a 15%Si/C-graphite/carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.83 401 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor nitrogen and lithium signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well contributions related to the binder material.
Si-based materials for lithium-ion batteries VII. 70% surface-modified Si/C-carbon black/lithiated polyacrylic acid electrode
Authors: Haasch Richard T. , Abraham Daniel P.
Published: May 2020

X-ray photoelectron spectroscopy (XPS) was used to analyze a 70% Si/C-carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor copper, nitrogen, calcium, and lithium signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well contributions related to the binder material.
Si-based materials for lithium-ion batteries IX: 70% surface-modified Si/C/polyethylene glycol-carbon black/lithiated polyacrylic acid electrode
Authors: Haasch Richard T. , Abraham Daniel P.
Published: May 2020

X-ray photoelectron spectroscopy was used to analyze a 70% Si/C-carbon black/polyethylene glycol/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey scan was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor copper and lithium signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well as contributions related to the binder material.
Determining the Acceleration Due to Gravity and Friction Using the Ticker Tape Timer Method
Authors: Fontana Ethan , Yeung Chuck , Hall Jonathan C.
Published: May 2020

Measuring the acceleration due to gravity g is a part of most introductory physics classes. A standard method to do so is by using a ticker tape timer. However, frictional forces are usually not included in the analysis even though friction leads to an acceleration significantly smaller than g. In this note, we show how to obtain accurate values of both the gravitational acceleration and the friction force by making measurements with different masses. We also propose a way to organize the laboratory procedure to make the multiple measurements needed, to be more collaborative, and to require students to think more carefully about their results. Students are also exposed to the importance of accounting for the variability in measurements.
Expanding the Boundaries of TPSR and Empowering Others to Make Their Own Contributions
Authors: Gordon Barrie , Beaudoin Sylvie
Published: May 2020

Purpose: The purpose of this article was to examine the geographical spread of teaching personal and social responsibility (TPSR), the extensive range of new populations and cultures that TPSR has been implemented with, and to consider the resulting challenges of this growth.Method: Information was gathered from published articles, dissertations, professional articles, and program descriptions and systematically analyzed for program fidelity.Results: A total of 31 countries were identified as having some level of TPSR presence, and there was a great deal of diversity in how, where, and to whom the programs are implemented.Discussion: The proliferation of TPSR will continue, and as this occurs, there will be increasing challenges in maintaining fidelity to the model.Conclusion: To meet this challenge, ongoing research, quality professional development, and the growth of communities of TPSR practice will be crucial.
De novo protein design enables the precise induction of RSV-neutralizing antibodies
Authors: Sesterhenn Fabian , Yang Che , Bonet Jaume , Cramer Johannes T. , Wen Xiaolin , Wang Yimeng , Chiang Chi-I , Abriata Luciano A. , Kucharska Iga , Castoro Giacomo , Vollers Sabrina S. , Galloux Marie , Dheilly Elie , Rosset Stéphane , Corthésy Patricia , Georgeon Sandrine , Villard Mélanie , Richard Charles-Adrien , Descamps Delphyne , Delgado Teresa , Oricchio Elisa , Rameix-Welti Marie-Anne , Más Vicente , Ervin Sean , Eléouët Jean-François , Riffault Sabine , Bates John T. , Julien Jean-Philippe , Li Yuxing , Jardetzky Theodore , Krey Thomas , Correia Bruno E.
Published: May 2020

TopoBuilding precision vaccines

To induce strong and targeted neutralizing antibody (nAb) responses against vaccine targets, one strategy has been to use computationally designed immunogens. However, the structural complexity of many known neutralization epitopes has posed a major challenge for the design of accurate epitope mimetics. Sesterhenn
et al.
created a protein design algorithm called TopoBuilder to design scaffolds for irregular and discontinuous neutralization epitopes. As a proof of principle, the authors generated epitope-focused immunogens based on the prefusion conformation of the respiratory syncytial virus (RSV) fusion protein. When these immunogens were used to vaccinate mice and nonhuman primates in RSV infection models, they generated targeted nAb responses to RSV and boosted site-specific nAb responses in heterologous prime-boost vaccination schemes.

Science
, this issue p.
eaay5051
An intrinsic oscillator drives the blood stage cycle of the malaria parasite
Plasmodium falciparum
Authors: Smith Lauren M. , Motta Francis C. , Chopra Garima , Moch J. Kathleen , Nerem Robert R. , Cummins Bree , Roche Kimberly E. , Kelliher Christina M. , Leman Adam R. , Harer John , Gedeon Tomas , Waters Norman C. , Haase Steven B.
Published: May 2020

Plasmodium
's inner clock

Malarial fevers are notably regular, occurring when parasitized red blood cells rupture synchronously to release replicated parasites. It has long been speculated that the
Plasmodium
parasites that cause malaria must therefore have intrinsic circadian clocks to be able to synchronize like this. Two groups have now probed gene expression in experiments and models using data obtained during the developmental cycles of
P. falciparum
in vitro and in the mouse model of
P. chabaudi
malaria. Smith
et al.
discovered that four strains of
P. falciparum
have circadian and cell cycle oscillators, each with distinctive periodicities that can be experimentally manipulated. Rijo-Ferreira
et al.
found that gene expression in
P. chabaudi
was strikingly rhythmic, persisted during constant darkness and in infections of arrhythmic mice, and synchronized by entraining to the host's periodicity.

Science
, this issue p.
754
, p.
746