bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunophenotypic quantification of M1 and M2 macrophage polarization in radicular cysts of primary and permanent teeth
Authors: Bertasso A. S. , Léon J. E. , Silva R. A. B. , Silva L. A. B. , de Queiroz A. M. , Pucinelli C. M. , Romualdo P. C. , Nelson‐Filho P.
Published: December 2019

Aim

To quantify M1 and M2 macrophages in radicular cysts of permanent (n = 14 cases) and primary teeth (n = 15 cases).

Methodology

All patients who attended the School of Dentistry Ribeirão Preto, University of São Paulo with primary teeth or permanent molars that were scheduled for extraction and fulfilled the inclusion criteria: absence of pain; presence/absence of fistulae; extensive coronal destruction due to caries lesions without possibility of restoration; pulp necrosis; radiographically visible apical periodontitis; and no previous treatment, were selected. The radicular cysts were removed and subsequently submitted to histopathologic analysis in order to classify the type of inflammatory infiltrate. In addition, CD68 (M1+, M2+) and CD163 (M1−, M2+) markers were quantified through an immunohistochemistry analysis. The data acquired were submitted to a Mann–Whitney test, with a 5% significance level.

Results

The patients had a mean age of 38.6 years and 5.9 years for cysts associated with permanent and primary teeth, respectively. In the histopathological analysis, no significant difference (P = 0.87) was found between radicular cysts in primary and permanent teeth regarding the intensity of the chronic inflammatory infiltrate. A significantly greater prevalence of M2 macrophages (P < 0.05) was observed in the lesions of both permanent and primary teeth, even though both M1 and M2 macrophages were detected. No significant difference (P > 0.05) was found for M1 and M2 macrophages associated with the cysts of primary and permanent teeth.

Conclusion

M1 and M2 macrophages were present in radicular cysts associated with primary and permanent teeth, with a greater quantity of M2 cells. The immunophenotypic quantification of M1 and M2 macrophage polarization in radicular cysts associated with primary and permanent teeth were similar.
Autoantibodies and B Cells: The ABC of rheumatoid arthritis pathophysiology
Authors: Volkov Mikhail , van Schie Karin Anna , van der Woude Diane
Published: December 2019

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation. In the last few decades, new insights into RA‐specific autoantibodies and B cells have greatly expanded our understanding of the disease. The best‐known autoantibodies in RA—rheumatoid factor (RF) and anti‐citrullinated protein antibodies (ACPA)—are present long before disease onset, and both responses show signs of maturation around the time of the first manifestation of arthritis. A very intriguing characteristic of ACPA is their remarkably high abundance of variable domain glycans. Since these glycans may convey an important selection advantage of citrulline‐reactive B cells, they may be the key to understanding the evolution of the autoimmune response. Recently discovered autoantibodies targeting other posttranslational modifications, such as anti‐carbamylated and anti‐acetylated protein antibodies, appear to be closely related to ACPA, which makes it possible to unite them under the term of anti‐modified protein antibodies (AMPA). Despite the many insights gained about these autoantibodies, it is unclear whether they are pathogenic or play a causal role in disease development. Autoreactive B cells from which the autoantibodies originate have also received attention as perhaps more likely disease culprits. The development of autoreactive B cells in RA largely depends on the interaction with T cells in which HLA “shared epitope” and HLA DERAA may play an important role. Recent technological advances made it possible to identify and characterize citrulline‐reactive B cells and acquire ACPA monoclonal antibodies, which are providing valuable insights and help to understand the nature of the autoimmune response underlying RA. In this review, we summarize what is currently known about the role of autoantibodies and autoreactive B cells in RA and we discuss the most prominent hypotheses aiming to explain the origins and the evolution of autoimmunity in RA.
Semiconductor‐conductor transition of pristine polymer‐derived ceramics SiC pyrolyzed at temperature range from 1200°C to 1800°C
Authors: Chowdhury Md Atiqur Rahman , Wang Kewei , Jia Yujun , Xu Chengying
Published: December 2019

This paper studies the effect of pyrolysis temperature on the semiconductor‐conductor transition of pristine polymer‐derived ceramic silicon carbide (PDC SiC). A comprehensive study of microstructural evolution and conduction mechanism of PDC SiC pyrolyzed at the temperature range of 1200°C‐1800°C is presented. At relatively lower pyrolysis temperatures (1200°C‐1600°C), the carbon phase goes through a microstructural evolution from amorphous carbon to nanocrystalline carbon. The PDC SiC samples behave as a semiconductor and the electron transport is governed by the band tail hopping (BTH) mechanism in low pyrolysis temperature (1300°C); by a mixed mechanism driven by band tail hopping and tunneling at intermediate temperature (1500°C). At higher pyrolysis temperatures (1700°C‐1800°C), a percolative network of continuous turbostratic carbon is formed up along the grain boundary of the crystallized SiC. The samples demonstrate metal‐like conductive response and their resistivity increases monotonically with the increasing measuring temperature.
Descriptive and experimental evidence for timing‐mediated polygyny risk in a pied flycatcher Ficedula hypoleuca population
Authors: Lamers Koosje P. , Nicolaus Marion , Rakhimberdiev Eldar , Nilsson Jan‐Åke , Both Christiaan
Published: December 2019

In polygynous species with biparental care, mates are often acquired in succession. Most research has focussed on the cost of polygyny in secondary females, but primary females may also suffer from reduced paternal care. The likelihood of sharing a male may be higher for early laying females, which could counteract the fitness benefits of breeding early. In this study, we use 12 years of data on pied flycatchers Ficedula hypoleuca, to show that the likelihood of becoming a primary female of a polygynous male declines over the season. Moreover, we provide experimental evidence that early breeding elevates polygyny risk, through an experimental manipulation that introduced early breeding females to a population with later breeding phenology. We found that, independently of breeding date, primary females slightly more often experienced complete brood failures than monogamous females, but did not differ in number of fledged offspring among successful broods or number of locally returning recruits. However, apparent survival in subsequent years was substantially lower in primary females, indicating that they may compensate for reduced male care at the expense of future reproduction. Our study reveals that polygyny risk indeed increases with early breeding and entails a local survival cost for primary females. However, this cost is likely largely outweighed by fitness benefits of early breeding in most years. Hence it is unlikely that the increased polygyny risk of early breeding counteracts the fitness benefits, but it may reduce selection for breeding extremely early.
Exploring protective decision‐making in the context of impact‐based flood warnings
Authors: Meléndez‐Landaverde Erika R. , Werner Micha , Verkade Jan
Published: December 2019

Previous research has found that users fail to comprehend flood hazard warning messages as well as the possible impacts of the forecast events. A proposed way to improve understanding and uptake is the implementation of impact‐based warning services. However, even though extensive qualitative research has been done on the provision of these impact‐based warnings (IBWs) for different types of hazards and extreme events, there is still little scientific evidence that the additional information on impacts in flood warnings positively affects decisions made by the general public. The research reported here explores whether including messages of potential impacts increased the general public's likelihood of making a protective decision when provided with a flood warning. Nine hypothetical flood scenarios were presented to participants who were then asked to score their likelihood of making a specific protective decision. Participants were either presented IBWs or hazard flood warnings (HWs). Results show that IBWs indeed led to higher likelihoods of participants making a protective decision than HWs. Interestingly, we found that key factors identified in previous studies as influential elements in the decision‐making process had little impact on their decision. These factors include gender and previous experience with flood warnings.
Prevalence of underweight, wasting and stunting among young children with a significant cognitive delay in 47 low‐income and middle‐income countries
Authors: Emerson E. , Savage A. , Llewellyn G.
Published: December 2019

Background

Undernutrition in early childhood is associated with a range of negative outcomes across the lifespan. Little is known about the prevalence of exposure to undernutrition among young children with significant cognitive delay.

Method

Secondary analysis of data collected on 161 188 three‐ and four‐year‐old children in 47 low‐income and middle‐income countries in Rounds 4–6 of UNICEF's Multiple Indicator Cluster Surveys. Of these, 12.3% (95% confidence interval 11.8–12.8%) showed evidence of significant cognitive delay.

Results

In both middle‐income and low‐income countries, significant cognitive delay was associated with an increased prevalence of exposure to three indicators of undernutrition (underweight, wasting and stunting). Overall, children with significant cognitive delay were more than twice as likely than their peers to be exposed to severe underweight, severe wasting and severe stunting. Among children with significant cognitive delay (and after controlling for country economic classification group), relative household wealth was the strongest and most consistent predictor of exposure to undernutrition.

Conclusions

Given that undernutrition in early childhood is associated with a range of negative outcomes in later life, it is possible that undernutrition in early childhood may play an important role in accounting for health inequalities and inequities experienced by people with significant cognitive delay in low‐income and middle‐income countries.
GAS‐HYDRATE SYSTEMS AND GAS VOLUMETRIC ASSESSMENT IN THE LOWER FANGLIAO BASIN, TAIWAN ACCRETIONARY WEDGE
Authors: Dirgantara F. , Lin A. T‐S. , Liu C‐S. , Lin C‐C. , Chen S‐C.
Published: December 2019

The accretionary wedge in the incipient arc‐continent collisional zone offshore southwestern Taiwan is rich in gas hydrates as inferred from reflection seismic data and the geochemical analyses of shallow sediments. In this study, 2D and 3D seismic data were used to investigate the role of structural factors including mud diapirism on the formation of gas hydrates and associated free gas in the Quaternary Lower Fangliao Basin, a semi‐enclosed slope basin situated on the upper accretionary wedge. Albeit limited drilling information on lithostratigraphy and petroleum potential in the area together with seismic reflection data show that mud diapirs have influenced the formation of bottom‐simulating reflectors (BSRs) and the distribution of gas hydrates and free gas. On reflection seismic profiles, five seismic facies were observed and are characterised by: stratified parallel reflections; contorted reflections; semi‐parallel, high‐amplitude reflections; oblique, continuous high‐amplitude reflections; and generally transparent reflections. These seismic facies were respectively interpreted as hemipelagic sediments, mass transport deposits (MTDs), sandstone‐rich turbidites, overbank deposits and mud diapirs. The gas hydrate stability zone (GHSZ) is characterized by (i) high amplitude reflections with an analogous phase to that of seafloor, possibly indicating potential porous sandstone‐rich turbidite reservoirs; (ii) BSRs showing polarity reversal relative to seafloor, suggesting higher impedance gas hydrates overlying lower impedance intervals with free gas; (iii) blanking reflections in fault zones, interpreted as gas‐bearing fluid conduits; (iv) strong reflections on the flanks of mud diapirs (e.g. flank drags) and above buried mud diapirs, demonstrating the presence of gas hydrates; (v) high amplitude reflections dragging on diapiric flanks with reversed phase to that of seafloor, indicating free gas ‐charged zones abutting mud diapirs; and (vi) the presence of focused advection and diffusion flow through mud diapirs and faults, which is interpreted to control the migration of thermogenic gas. Based on the distribution of seismic amplitude characteristics and reflection strength with respect to depth of the BSRs, hydrocarbon prospects can be divided into gas‐hydrate compartments above BSRs, free gas compartments above BSRs, and free gas compartments below BSRs. From a combination of geobody extraction and Monte Carlo simulation, the prospects appear to hold about 2048 Bcf (billion cubic feet) of total gas volume over a study area of 60 km2. These observations provide first‐order estimates of methane resources in the Lower Fangliao Basin offshore southwestern Taiwan.
Preparation and evaluation of a novel solid dispersion using leucine as carrier
Authors: Xia Xiaojing , Tan Zeng , Fan Yaru , Hu Ying , Deng Jin
Published: December 2019

Objective

The aim of this study was to develop a novel formulation of oleanolic acid (OA) solid dispersion (SD), using leucine (Leu) as the carrier to improve OA oral bioavailability.

Methods

The OA-Leu SD was prepared by solvent evaporation and was evaluated in vitro using differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, flowability, hygroscopicity and dissolution test. The stability of the SD was evaluated using accelerated testing. In vivo pharmacokinetic tests were performed in male Sprague Dawley rats using a liquid chromatography tandem-mass spectrometry bioanalytical method.

Key findings

OA-Leu SD was successfully prepared, and OA was mostly in an amorphous state. More than 80% of OA could dissolve in OA-Leu SD in 20 min, while only 13.4% of free OA dissolved. The powder flow of OA-Leu SD was clearly improved compared with free OA and its moisture absorption was 3.4%. The accelerated testing further demonstrated that SD could maintain OA in an amorphous state at 40 °C for 6 months. OA-Leu SD showed higher relative oral bioavailability (189.7%) than free OA in rats.

Conclusions

Using Leu as a carrier produced a SD with good flowability, low hygroscopicity and high bioavailability.
Effect of atorvastatin on Aβ1–42-induced alteration of SESN2, SIRT1, LC3II and TPP1 protein expressions in neuronal cell cultures
Authors: Çelik Hande , Karahan Hande , Kelicen-Uğur Pelin
Published: December 2019

Objectives

Sestrins (SESNs) and sirtuins (SIRTs) are antioxidant and antiapoptotic genes and crucial mediators for lysosomal autophagy regulation that play a pivotal role in the Alzheimer's disease (AD). Recently, statins have been linked to the reduced prevalence of AD in statin-prescribed populations yet molecular basis for the neuroprotective action of statins is still under debate.

Methods

This study was undertaken whether Aβ-induced changes of SESN2 and SIRT1 protein expression, autophagy marker LC3II and lysosomal enzyme TPP1 affected by atorvastatin (Western blot) and its possible role in Aβ neurotoxicity (ELISA).

Key findings/results

We showed that SESN2 and LC3II expressions were elevated, whereas SIRT1 and TPP1 expressions were decreased in the Aβ1–42-exposed human neuroblastoma cells (SH-SY5Y). Co-administration of atorvastatin with Aβ1–42 compensates SESN2 increase and recovers SIRT1 decline by reducing oxidative stress, decreasing SESN2 expression and increasing SIRT1 expression by its neuroprotective action. Atorvastatin induced LC3II but not TPP1 level in the Aβ1–42-exposed cells suggested that atorvastatin is effective in the formation of autophagosome but not on the expression of the specific lysosomal enzyme TPP1.

Discussion and conclusion

Together, these results indicate that atorvastatin induced SESN2, SIRT1 and LC3II levels play a protective role against Aβ1–42 neurotoxicity.
The influence of age and body weight gain on enrofloxacin pharmacokinetics in turkeys—Allometric approach to dose optimization
Authors: Poźniak Błażej , Tikhomirov Marta , Motykiewicz‐Pers Karolina , Bobrek Kamila , Świtała Marcin
Published: December 2019

Enrofloxacin is a concentration‐dependent antimicrobial used in bacterial infections in poultry. During a few months of a turkey's life, pharmacokinetics of drugs undergoes substantial changes which may compromise their efficacy due to variability in internal exposure (measured by area under the concentration–time curve, AUC). The aim of this study was to describe the effects of age on the pharmacokinetics of a single intravenous (i.v.) and oral administration of enrofloxacin at a dose of 10 mg/kg to turkeys. It was found that during a 2.5‐month‐long period of growth from 1.4 to 14.6 kg, the AUC after i.v. administration increased almost threefold due to a significant decrease in the body clearance (from a mean of 0.76–0.28 L hr−1 kg−1). Over the same period, the mean elimination half‐life was prolonged from 2.65 to 7.03 hr. Oral administration resulted in a similar trend in pharmacokinetic parameters. For both routes, formation of the major metabolite, ciprofloxacin, was marginal. Protein binding was not age‐dependent and never exceeded 50%. Body clearance, volume of distribution and elimination half‐life were subjected to an allometric analysis and a novel, nonlinear dosage protocol has been proposed to improve the internal exposure to the drug in different age groups of turkeys.
Liver is widely eaten by preschool children in the Northern Cape province of South Africa: Implications for routine vitamin A supplementation
Authors: van Stuijvenberg Martha E. , Schoeman Serina E. , Nel Jana , le Roux Maretha , Dhansay Muhammad A.
Published: December 2019

Previous research has demonstrated a virtual absence of vitamin A deficiency and adequacy of vitamin A intake through consumption of liver in preschool children of a community in the Northern Cape province of South Africa where sheep farming is common, and liver, an exceptionally rich source of vitamin A, is frequently eaten. Only 60–75 g of liver per month is needed to meet the vitamin A requirement of preschool children. Because this may have implications for routine vitamin A supplementation, and because liver consumption for the rest of the province is unknown, the study aim was to establish the prevalence and frequency of liver intake in a provincial‐wide survey. An unquantified liver‐specific food frequency questionnaire, covering a period of 1 month, complemented by a 1‐year recall, was administered to mothers of 2‐ to 5‐year‐old children (n= 2,864) attending primary health care facilities in all five districts and 26 subdistricts. A total of 86% of children were reported to eat liver, which was eaten in all districts by at least 80% of children. The overall median frequency of liver intake was 1.0 [25th, 75th percentiles: 0.5, 3.0] times per month and ranged from 1.0 [0.3, 2.0] to 2.0 [1.0, 4.0] for the various districts. Based on a previously reported portion size of 66 g, these results suggest vitamin A dietary adequacy in all districts and possibly also vitamin A intake exceeding the Tolerable Upper Intake Level in some children. Routine vitamin A supplementation in this province may not be necessary and should be reconsidered.
Terminology and assessment tools of psychosis: A systematic narrative review
Authors: Seiler Natalie , Nguyen Tony , Yung Alison , O'Donoghue Brian
Published: December 2019

Aim

Phenomena within the psychosis continuum that varies in frequency/duration/intensity have been increasingly identified. Different terms describe these phenomena, however there is no standardization within the terminology. This review evaluated the definitions and assessment tools of seven terms – (i) ‘psychotic experiences’; (ii) ‘psychotic‐like experiences’; (iii) ‘psychotic‐like symptoms’; (iv) ‘attenuated psychotic symptoms’; (v) ‘prodromal psychotic symptoms’; (vi) ‘psychotic symptomatology’; and (vii) ‘psychotic symptoms’.

Methods

EMBASE, MEDLINE, and CINAHL were searched during February–March 2019. Inclusion criteria included 1989–2019, full text, human, and English. Papers with no explicit definition or assessment tool, duplicates, conference abstracts, systematic reviews, meta‐analyses, or no access were excluded.

Results

A total of 2238 papers were identified and of these, 627 were included. Definitions and assessment tools varied, but some trends were found. Psychotic experiences and psychotic‐like experiences were transient and mild, found in the general population and those at‐risk. Psychotic‐like symptoms were subthreshold and among at‐risk populations and non‐psychotic mental disorders. Attenuated psychotic symptoms were subthreshold but associated with distress, risk, and help‐seeking. Prodromal psychotic symptoms referred to the prodrome of psychotic disorders. Psychotic symptomatology included delusions and hallucinations within psychotic disorders. Psychotic symptoms was the broadest term, encompassing a range of populations but most commonly involving hallucinations, delusions, thought disorder, and disorganization.

Discussion

A model for conceptualizing the required terms is proposed and future directions needed to advance this field of research are discussed.
Photosynthetic activity in two heteromorphic life‐history stages of a freshwater red alga,Thorea gaudichaudii(Thoreales) from Japan, in response to an irradiance and temperature gradient
Authors: Kozono Jumpei , Nishihara Gregory N. , Endo Hikaru , Terada Ryuta
Published: December 2019

We determined the effect of irradiance and temperature on the photosynthesis of two heteromorphic life‐history stages of an endangered freshwater red alga,Thorea gaudichaudii(Thoreales) by laboratory and field measurements. Net oxygenic photosynthesis–irradiance models of macroscopic and microscopic life‐history stages revealed similar low irradiance‐adapted responses, with a compensation irradiance (Ec) of 6.71 and 2.56 μmol photons m−2s−1(4.30–9.13 and 0.13–7.19, 95% Bayesian prediction interval, BPI) and saturating irradiance (Ek) of 26.6 and 30.0 μmol photons m−2s−1(19.0–37.4 and 12.1–63.0, BPI), respectively. A temperature‐dependent model of net photosynthesis and dark respiration in macroscopic and microscopic stages also showed similar temperature responses, and the gross photosynthetic rate (GPmax), 3.54 and 6.34 μg O2gww−1min−1(3.10–3.99 and 5.31–8.21, BPI), was highest at 32.1 and 35.7°C (29.8–34.0 and 29.5–48.6, BPI). The maximum quantum yields (Fv/Fm) in macroscopic and microscopic stages were also similar in response with respect to temperature; however, it was somewhat steady at low temperatures with the highest value of 0.54 and 0.62 (0.54–0.55 and 0.61–0.63, BPI) at 17.8 and 15.0°C (16.7–18.8 and 12.3–17.1, BPI). The effective quantum yield (ΦPSII) in macroscopic and microscopic stages was also negatively correlated with irradiance, which decreased after 12 h of continuous exposure to 50 (low) and 1000 (high) μmol photons m−2s−1at 12 and 22°C. Large declines ofΦPSIIand subsequent failure ofFv/Fmrecovery were particularly enhanced at high irradiance, signifying photoinhibition. Diurnal change ofΦPSIIand incident irradiance of the macroscopic stage under the field measurement revealed the midday depression ofΦPSII; however, there was little direct sunlight due to shading by the trees, and algae were occurring in the shaded locations in the freshwater spring.
Multivariate Type G Matérn Stochastic Partial Differential Equation Random Fields
Authors: Bolin David , Wallin Jonas
Published: December 2019

For many applications with multivariate data, random-field models capturing departures from Gaussianity within realizations are appropriate. For this reason, we formulate a new class of multivariate non-Gaussian models based on systems of stochastic partial differential equations with additive type G noise whose marginal covariance functions are of Matérn type. We consider four increasingly flexible constructions of the noise, where the first two are similar to existing copula-based models. In contrast with these, the last two constructions can model non-Gaussian spatial data without replicates. Computationally efficient methods for likelihood-based parameter estimation and probabilistic prediction are proposed, and the flexibility of the models suggested is illustrated by numerical examples and two statistical applications.
HIV prevalence and incidence estimates among blood donors in five regions in China
Authors: Shi Ling , Liu Yu , Wang Jingxing , Zeng Peibin , Gao Zhan , Wang Shaoli , Fu Ping , Liu Jing , Mao Wei , He Weilan , Ma Hongli , Huang Mei , Wan Jianhua , Liao Dan , Brambilla Donald , Sullivan Marian , Zou Shimian , Ness Paul , He Miao , Shan Hua ,   for the International Component of the NHLBI Recipient Epidemiology and Donor Evaluation Study‐III (REDS‐III)
Published: December 2019

BACKGROUND

Previous data, although scant, indicated that the incidence of HIV in China has increased over the past decade. There is a growing concern about the impact of the HIV epidemic on blood safety.

METHODS AND MATERIALS

We used donation data from five geographically‐disperse blood centers in 2013‐2016 participating in the Recipient Epidemiology and Donor Evaluation Study‐III (REDS–III) China program to estimate HIV prevalence and incidence among blood donors. Multivariable logistic regression model was used to examine factors associated with HIV infection in Chinese blood donors.

RESULTS

The overall HIV prevalence among first‐time donors from 2013 through 2016 was 68.04 per 100,000 donors (95% CI 61.68–74.40). The HIV incidence rate was estimated to be 37.93 per 100,000 person‐years (95% CI 30.62–46.97) among first‐time donors and 20.55 per 100,000 person‐years (95% CI 16.95–24.91) among repeat donors. There was substantial variation in HIV prevalence and incidence rates across blood centers. Multivariable logistic regression results showed that among first‐time donors, being male, older than 25 years, minority ethnicity, less than college education, and certain occupations (commercial services, factory workers, retired, unemployed, or self‐employed) were associated with positive HIV confirmatory testing results.

CONCLUSION

HIV prevalence and incidence among blood donors remain low in the selected five regions in China; however, an increasing trend is observed at some blood centers. It is important to monitor HIV epidemiology in Chinese blood donors on a continuous basis, especially among populations and regions of higher risk.
The left lateral projection is comparable to horizontal beam radiography for identifying experimental small volume pneumoperitoneum in the canine abdomen
Authors: Ng Jiaying , Linn Kathleen A. , Shmon Cindy L. , Parker Sarah , Zwicker Lesley A.
Published: December 2019

Nontraumatic spontaneous pneumoperitoneum suggests the presence of gastrointestinal perforation; early detection can be lifesaving. Horizontal beam projections have been reported to be more sensitive than standard radiographic views for detecting small volumes of free peritoneal gas. This prospective, experimental, analytical study compared both left lateral (LL) and ventrodorsal (VD) standard views to horizontal beam projections for detecting small volumes of artificially induced pneumoperitoneum in live dogs. The effect of radiology training on accurate detection of small amounts of free peritoneal air was also assessed. Fourteen dogs had four radiographic projections taken after injection of 0, 2.5, 5, and 10 mL of cumulative air into their abdominal cavities. Radiographs were interpreted individually by three American College of Veterinary Radiology‐certified radiologists and three small animal internship‐trained veterinarians who were blinded to the air volume injected. At 2.5 and 10 mL of air injected, the LL projection had highest odds of an accurate response (odds ratio [OR] = 2.4 and 99.0 when compared to VD horizontal and VD projections, respectively). At 5 mL of air injected, the lateral horizontal (LH) projection had the highest odds of an accurate response (OR = 3.2 compared to VD horizontal). The LL projection was not significantly different from the LH projection at all volumes of air injected. Board certification led to higher odds of accurate responses at volumes of 5 (OR = 2.2) and 10 mL (OR = 3.6), as compared to nonspecialist veterinarians. Overall, LH and standard LL appeared to be the most useful radiographic projections for detection of small amounts of free peritoneal gas.
Understanding the Impact of Decision Making on Robustness During Complex System Design: More Resilient Power Systems
Authors: Piacenza Joseph R. , Faller Kenneth John , Bozorgirad Mir Abbas , Cotilla-Sanchez Eduardo , Hoyle Christopher , Tumer Irem Y.
Published: December 2019

Robust design strategies continue to be relevant during concept-stage complex system design to minimize the impact of uncertainty in system performance due to uncontrollable external failure events. Historical system failures such as the 2003 North American blackout and the 2011 Arizona-Southern California Outages show that decision making, during a cascading failure, can significantly contribute to a failure's magnitude. In this paper, a scalable, model-based design approach is presented to optimize the quantity and location of decision-making agents in a complex system, to minimize performance loss variability after a cascading failure, regardless of where the fault originated in the system. The result is a computational model that enables designers to explore concept-stage design tradeoffs based on individual risk attitudes (RA) for system performance and performance variability, after a failure. The IEEE RTS-96 power system test case is used to evaluate this method, and the results reveal key topological locations vulnerable to cascading failures, that should not be associated with critical operations. This work illustrates the importance of considering decision making when evaluating system level tradeoffs, supporting robust design.
Robust Fixed-Time Integral Sliding Mode Control of a Nonlinear Hydraulic Turbine Regulating System
Authors: Huang Sunhua , Wang Jie
Published: December 2019

The hydraulic turbine regulating system (HTRS) plays an important role in the safe and stable operation of hydropower stations. In this paper, a fixed-time integral sliding mode controller (FTISMC) is designed to make the nonlinear HTRS with disturbances stable in a fixed time. The HTRS is a highly complex, strongly coupled, nonlinear nonminimum phase system, which can ensure the frequency and rotor angle of generator stability by adjusting the guide vane opening. In order to decouple the nonlinear HTRS, the input/output feedback linearization is applied to establish the relationship between the control input and the output of the HTRS. Based on sliding mode control (SMC) theory and fixed-time stability theory, FTISMC is proposed to stabilize the HTRS in a fixed time. Compared with the finite time control method (FTCM), the convergence time of nonlinear HTRS under FTISMC is independent of initial conditions and can be exactly estimated. Meanwhile, the integral sliding surface can avoid singularity, thus eliminating the chattering phenomenon. Finally, the numerical simulation is implemented to demonstrate the superior performances of the proposed FTISMC than the existing PID, SMC, and FTMC.
Computational Investigation of Flow Over Nose Cap of Closed Impeller of Mixed Flow Centrifugal Pump
Authors: Mandhare Neeta Amol , Karunamurthy K. , Ismail Saleel
Published: December 2019

Flow turbulence near the suction region and over the eye of a closed impeller may be troublesome during the operation of a centrifugal pump. This article aims to bring out a methodology for minimization of flow turbulence and for providing guidance to suction flow by modifying the surface design of the lock nut into a nose cap of optimized profile. The effects of this modification on the performance parameters of closed impeller of a low head, mixed flow centrifugal pump are presented here. Based on geometric constraints and impeller eye diameter, nose caps of 65 mm diameter and various nose tip angles (15–90 deg) and lengths (50–80 mm) are evaluated. Parametric studies are carried out via computational fluid dynamics (CFD) analyses using ansysfluent 17.0 as well as experimental investigations to investigate the effects on head, energy consumption, and overall efficiency for flowrates in the range of 0.25–1.5 times the flowrate at best efficiency point (BEP). The estimates of head developed obtained using CFD and experimental studies match within 4.23%. Results confirm improvement in performance parameters like head and overall efficiency due to the reduction of losses and better flow guidance in the suction region. The performance improvement is greatest for the nose cap of 900 tip angle and 50 mm length at all flowrates.
Determination of Folias Factor for Failure Pressure of Corroded Pipeline
Authors: Sun Mingming , Li Xin , Liu Jinkun
Published: December 2019

Corrosion assessment and burst pressure prediction of line pipes with corrosion defects are essential for the integrity assessment of steel transmission pipelines. The failure assessment methods proposed in codes or handbooks may be overly conservative or exhibit significant scatter in their predictions. In this paper, the effects of two key parameters—the flow stress and Folias bulging factor, on predicting the failure pressure of pipelines with defects are studied. The Folias bulging factor is suggested by fitting the results from finite element (FE) analysis. Then, a new prediction method for the failure pressure of pipelines with defects is proposed. The failure pressures predicted by the proposed method are in better agreement with the experimental results than the results by the other methods such as B31G, MB31G, Det Norske Veritas (DNV), and rectangular parabolic area (RPA).
Imperfection Insensitivity of Thin Wavy Cylindrical Shells Under Axial Compression or Bending
Authors: Yadav Kshitij Kumar , Gerasimidis Simos
Published: December 2019

The presence of imperfections significantly reduces the load carrying capacity of thin cylindrical shells due to the high sensitivity of thin shells to imperfections. To nullify this unfavorable characteristic, thin cylindrical shells are designed using a conservative knockdown factor method, which was developed by NASA in the late 1960s. Almost all the design codes, explicitly or implicitly, follow this approach. Recently, a new approach has emerged to significantly reduce the sensitivity of thin cylindrical shells. In this approach, wavy cross sections are used instead of circular cross sections for creating thin cylinders. Past studies have demonstrated the effectiveness of wavy cylinders to reduce imperfection sensitivity of thin cylinders under axial compression assuming linear elastic material behavior. These studies used eigenmode imperfections which do not represent realistic imperfections found in cylinders. In this paper, using a realistic dimple-like imperfection, new insights are presented into the response of wavy cylinders under uniform axial compression and bending. Furthermore, the effectiveness of the wavy cylinders to reduce imperfection sensitivity under bending load is investigated assuming a plastic Ramberg–Osgood material model. The effect of wave parameters, e.g., the amplitude and the number of waves, is also explored. This study reveals that wavy thin cylinders are insensitive to imperfections under bending in the inelastic range of the material. It is also found that the wave parameters play a decisive role in the response of thin wavy cylinders to imperfections under bending.
Ignition Delay Times of Oxy-Syngas and Oxy-Methane in Supercritical CO2 Mixtures for Direct-Fired Cycles
Authors: Barak Samuel , Pryor Owen , Ninnemann Erik , Neupane Sneha , Vasu Subith , Lu Xijia , Forrest Brock
Published: December 2019

The direct-fired supercritical CO2 (sCO2) cycles promise high efficiency and reduced emissions while enabling complete carbon capture. However, there is a severe lack of fundamental combustion kinetics knowledge required for the development and operation of these cycles, which operate at high pressures and with high CO2 dilution. Experiments at these conditions are very challenging and costly. In this study, a shock tube was used to investigate the auto-ignition tendencies of several mixtures under high carbon dioxide dilution and high fuel loading. Individual mixtures of oxy-syngas and oxy-methane fuels were added to CO2 bath gas environments and ignition delay time data were recorded. Reflected shock pressures neared 100 atm, above the critical pressure of carbon dioxide into the supercritical regime. In total, five mixtures were investigated with a pressure range of 70–100 atm and a temperature range of 1050–1350 K. Measured ignition delay times of all mixtures were compared with two leading chemical kinetic mechanisms for their predictive accuracy. The mixtures included four oxy-syngas and one oxy-methane compositions. The literature mechanisms tended to show good agreement with the data for the methane mixture, while these models were not able to accurately capture all behavior for syngas mixtures tested in this study. For this reason, there is a need to further investigate the discrepancies. To the best of our knowledge, we report the first ignition data for the selected mixtures at these conditions. Current work also highlights the need for further work at high pressures to fully understand the chemical kinetic behavior of these mixtures to enable the sCO2 power cycle development.
Analytic Solutions as a Tool for Verification and Validation of a Multiphysics Model
Authors: Tregillis I. L. , Koskelo Aaron
Published: December 2019

Computational physicists are commonly faced with the task of resolving discrepancies between the predictions of a complex, integrated multiphysics numerical simulation, and corresponding experimental datasets. Such efforts commonly require a slow iterative procedure. However, a different approach is available in casesx where the multiphysics system of interest admits closed-form analytic solutions. In this situation, the ambiguity is conveniently broken into separate consideration of theory–simulation comparisons (issues of verification) and theory–data comparisons (issues of validation). We demonstrate this methodology via application to the specific example of a fluid-instability-based ejecta source model under development at Los Alamos National Laboratory and implemented in flag, a Los Alamos continuum mechanics code. The formalism is conducted in the forward sense (i.e., from source to measurement) and enables us to compute, purely analytically, time-dependent piezoelectric ejecta mass measurements for a specific class of explosively driven metal coupon experiments. We incorporate published measurement uncertainties on relevant experimental parameters to estimate a time-dependent uncertainty on these analytic predictions. This motivates the introduction of a “compatibility score” metric, our primary tool for quantitative analysis of the RMI + SSVD model. Finally, we derive a modification to the model, based on boundary condition considerations, that substantially improves its predictions.
A Novel Indirect Visualization Method for Studying the Melting Heat Transfer of Nano-Enhanced Phase Change Materials Using Thermochromic Liquid Crystal Thermography
Authors: Hu Nan , Li Zi-Rui , Zhang Run-Hui , Fan Li-Wu
Published: December 2019

In order to give more sights into the melting (and solidification) heat transfer processes of nano-enhanced phase change material (NePCM) with invisible phase interfaces, a novel indirect method for tracking the phase interface by thermochromic liquid crystal (TLC) thermography is proposed. As an example case to demonstrate the applicability of the proposed method, the classical problem of melting heat transfer in a differentially heated rectangular cavity was revisited in the presence of NePCM of various loadings. A narrowband TLC was selected and calibrated carefully to build the hue–temperature relationship prior to being applied in the melting experiments. For validation purpose, the case of an unloaded NePCM, with a clear visible phase interface, was tested via combined direct and indirect observations. It was shown that this TLC method can easily and accurately capture the dynamic motions of the phase interface during melting. Based on the shape evolutions of the phase interface, it was concluded that for the NePCM sample with a higher loading (and hence a much greater viscosity), heat conduction becomes the dominant mode of heat transfer during melting as a result of the significantly deteriorated natural convection effect. This gives an intuitive confirmation of the hypothesis made in previous studies that were conducted using volume-average-based indirect methods.
Pressure Drop and Heat Transfer Performance of Microchannel Heat Exchanger With Circular Reentrant Cavities and Ribs
Authors: Hou Tingbo , Chen Yuanlong
Published: December 2019

The rib arrangement has an important influence on the pressure drop and heat transfer performance of a microchannel heat exchanger (MHE) with circular reentrant cavities and ribs. In this study, four kinds of MHEs with circular reentrant cavity and ribs were designed, namely, circular reentrant cavities (circular), circular reentrant cavities and single-sided ribs (circular—single), circular reentrant cavities and odd-symmetric ribs (circular—odd), and circular reentrant cavities and double symmetric ribs (circular—double). The effect of the rib arrangement on the pressure drop and heat transfer performance of MHEs was numerically investigated by ansysfluent 15.0. The experimental platform was then designed and built for the subsequent experimental verification. The results showed that the pressure drop between the inlet and outlet of the MHE with circular reentrant cavities and ribs increased as the inlet flow increased. At the same inlet flowrate, the pressure drop between the inlet and outlet of the MHEs was largest for the circular reentrant cavities and double symmetric ribs, followed by the circular reentrant cavities and odd-symmetric ribs, circular reentrant cavities and single-sided ribs, and the circular reentrant cavities. The presence of the rib structure increased the inlet and outlet pressure drop of the MHE. The MHE with circular reentrant cavities and double symmetric ribs had the largest inlet and outlet pressure drop, followed by that with circular reentrant cavities and odd-symmetric ribs, that with circular reentrant cavities and single-sided ribs, and that with circular reentrant cavities, indicating that the latter exhibited the best pressure drop performance. At the same inlet flowrate, the MHE with circular reentrant cavities had the highest hot water outlet temperature and the MHE with circular reentrant cavities and double symmetric ribs had the lowest temperature, whereas the results were the opposite for the cold-water outlet temperature. This indicates that the heat transfer performance was best for the MHE with circular reentrant cavities and double symmetric ribs, followed by that with circular reentrant cavities and odd-symmetric ribs and that with circular reentrant cavities and single-sided ribs.
Numerical Investigation of Effect of Operating Parameters on the Phase Transformation During Vibration-Assisted Nano-Impact Machining of Silicon by Loose Abrasives
Authors: Duong Nick H. , Ma Jianfeng , Jahan Muhammad P. , Lei Shuting , Kore Vamshi Krishna , Sundaram Murali
Published: December 2019

Vibration-assisted nano-impact machining by loose abrasives (VANILA) is a newly developed process based on the atomic force microscope (AFM) platform, where the nanoabrasive (diamond particles) slurry is injected between the workpiece and the vibrating AFM probe. This study aims to use the commercial finite element method (FEM) software package abaqus to simulate the phase transformation experienced by the silicon workpiece and to study the effects of VANILA process parameters, such as impact speed, impact angle, and coefficient of friction between the nanoabrasive and silicon workpiece, on the volume of phase transformation of silicon. Among these three parameters, impact speed is found to have the most dominating effect on the phase transformation process, followed by impact angle and friction coefficient. It is found that the volumes for Si-VII, Si-VIII, and Si-X phases increase with the increase of impact speed from 100 m/s to 200 m/s. The phase volumes of Si-VII and Si-VIII are found to decrease slightly with the increase of friction coefficient from 0.05 to 0.5. The phase volumes for Si-VII, Si-VIII, and Si-X are found to increase with the increase of impact angles from 20 deg to 90 deg. Finally, the multiple linear regression modeling using a design of experiments is carried out to study the relationship among the three parameters and the volume of different phases of silicon.
Material-Oriented Regularization Toward Solving Manufacturing Inverse Problem in Ion Beam Microprocessing
Authors: Zhang Q. , Zhu X. P. , Zhu B. , Lei M. K. , Guo D. M.
Published: December 2019

A material-oriented regularization (MOR) methodology is developed to solve manufacturing inverse problem of estimating the manufacture input process parameters for a required output performance, demonstrated by ion beam microprocessing of tungsten components in future fusion reactors. The MOR methodology is explored as following steps: forward problem modeling, identification of characteristic material loading, and solving the inverse problem via the characteristic material loading. A thermodynamic model is established in forward problem scheme by comprehensively incorporating material constraints of tungsten, to simulate the output of residual surface stresses in top layer of several μm that determines fatigue performance of the microprocessed tungsten component. With the experimentally verified model, all material loading variables, i.e., thermal, elastic strain, and plastic strain energies can be explicitly described under the processing load of thermal energy input. Among the material loading variables, stored elastic strain energy is identified as characteristic material loading with a highest sensitivity in correlation to residual surface stresses, as process signature. The processing load of 2.1–4.2 J/cm2 is derived for a required residual surface stress in range of 0–1500 MPa within 15 μm depth, with an upper bound of the relative error of 4.7–11.7% for the inverse problem solution. The MOR enables comprehensive incorporation of material constraints with a self-convergence effect to effectively relax the ill-posedness of manufacturing inverse problems, otherwise in conventional regularizations such constraints have to be empirically adjusted in compromise with data fitting.
Creating Metal Molds for Directional Gecko-Inspired Adhesives
Authors: Kerst Capella , Suresh Srinivasan A. , Cutkosky Mark R.
Published: December 2019

We describe a process for creating durable metal molds for the fabrication of directional, gecko-inspired dry adhesives. The adhesives require microscopic inclined features with a challenging combination of tapered geometry, high aspect ratio, and smooth surface finish. Wedge-shaped features produced by the new metal mold exhibit the same geometry and surface finish as those cast from single-use wax molds and epoxy molds in previous fabrication methods. They also produce the same levels of adhesion and shear stress. The metal molds, and the adhesives cast from them, show no degradation after repeated molding cycles.