bluuebunny/crossref_metadata_2025 huggingface dataset:
Winter climate change and the poleward range expansion of a tropical invasive tree (Brazilian pepper—Schinus terebinthifolius)
Authors: Osland Michael J. , Feher Laura C.
Published: September 2019

Winter climate change is expected to lead to the tropicalization of temperate ecosystems, where tropical species expand poleward in response to a decrease in the intensity and duration of winter temperature extremes (i.e., freeze events). In the southeastern United States, freezing temperatures control the northern range limits of many invasive nonnative species. Here, we examine the influence of freezing temperatures and winter climate change on the northern range limits of an invasive nonnative tree—Schinus terebinthifolius (Brazilian pepper). Since introduction in the 1800s, Brazilian pepper has invaded ecosystems throughout south and central Florida to become the state's most widespread nonnative plant species. Although Brazilian pepper is sensitive to freezing temperatures, temperature controls on its northern distribution have not been adequately quantified. We used temperature and plant occurrence data to quantify the sensitivity of Brazilian pepper to freezing temperatures. Then, we examined the potential for range expansion under three alternative future climate scenarios (+2°C, +4°C, and +6°C). Our analyses identify a strong nonlinear sigmoidal relationship between minimum temperature and Brazilian pepper presence, with a discrete threshold temperature occurring near −11°C. Our future scenario analyses indicate that, in response to warming winter temperatures, Brazilian pepper is expected to expand northward and transform ecosystems in north Florida and across much of the Gulf of Mexico and south Atlantic coasts of the United States. These results underscore the importance of early detection and rapid response efforts to identify and manage the northward invasion of Brazilian pepper in response to climate change. Looking more broadly, our work highlights the need to anticipate and prepare for the tropicalization of temperate ecosystems by tropical invasive species.
Looking for freedom? Networks of international student mobility and countries’ levels of democracy
Authors: Vögtle Eva Maria , Windzio Michael
Published: September 2019

This article analyses the network of international student mobility between OECD and European Higher Education Area (EHEA) member countries between 2000 and 2009. It aims to investigate the link between countries’ levels of democracy and how this impacts on their ability to attract degree‐mobile students from abroad. Social network analysis and exponential random graph modelling are used to show that the ties of student mobility occur more often when both countries in the dyad have either low or high levels of democracy and when the receiving country is also economically wealthy. The network is characterised by a core–periphery structure where a few countries act as hubs with numerous strong ties. The overall results lend support to homophily assumptions about the network of internationally mobile students and show a considerable confounding of effects of democratisation and economic prosperity on international student mobility.
Practice guideline update summary: Acute treatment of migraine in children and adolescents
Authors: Oskoui Maryam , Pringsheim Tamara , Holler‐Managan Yolanda , Potrebic Sonja , Billinghurst Lori , Gloss David , Hershey Andrew D. , Licking Nicole , Sowell Michael , Victorio M. Cristina , Gersz Elaine M. , Leininger Emily , Zanitsch Heather , Yonker Marcy , Mack Kenneth
Published: September 2019

Objective

To provide evidence‐based recommendations for the acute symptomatic treatment of children and adolescents with migraine.

Methods

We performed a systematic review of the literature and rated risk of bias of included studies according to the American Academy of Neurology classification of evidence criteria. A multidisciplinary panel developed practice recommendations, integrating findings from the systematic review and following an Institute of Medicine‐compliant process to ensure transparency and patient engagement. Recommendations were supported by structured rationales, integrating evidence from the systematic review, related evidence, principles of care, and inferences from evidence.

Results

There is evidence to support the efficacy of the use of ibuprofen, acetaminophen (in children and adolescents), and triptans (mainly in adolescents) for the relief of migraine pain, although confidence in the evidence varies between agents. There is high confidence that adolescents receiving oral sumatriptan/naproxen and zolmitriptan nasal spray are more likely to be headache free at 2 hours than those receiving placebo. No acute treatments were effective for migraine‐related nausea or vomiting; some triptans were effective for migraine‐related phonophobia and photophobia.

Recommendations

Recommendations for the treatment of acute migraine in children and adolescents focus on the importance of early treatment, choosing the route of administration best suited to the characteristics of the individual migraine attack, and providing counselling on lifestyle factors that can exacerbate migraine, including trigger avoidance and medication overuse.
Sequences of toddler negative emotion and parent–toddler verbal communication during a waking day
Authors: Fields‐Olivieri Margaret A. , Cole Pamela M.
Published: September 2019

Although the second year of life is characterized by dramatic changes in expressive language and by increases in negative emotion expression, verbal communication and emotional communication are often studied separately. With a sample of twenty‐five one‐year‐olds (12–23 months), we used Language Environment Analysis (LENA; Xu, Yapanel, & Gray, 2009, Reliability of the LENA™ language environment analysis system in young children’s natural home environment. LENA Foundation) to audio‐record and quantify parent–toddler communication, including toddlers’ vocal negative emotion expressions, across a full waking day. Using a multilevel extension of lag‐sequential analysis, we investigated whether parents are differentially responsive to toddlers’ negative emotion expressions compared to their verbal or preverbal vocalizations, and we examined the effects of parents’ verbal responses on toddlers’ subsequent communicative behavior. Toddlers’ negative emotions were less likely than their vocalizations to be followed by parent speech. However, when negative emotions were followed by parent speech, toddlers were most likely to vocalize next. Post hoc analyses suggest that older toddlers and toddlers with higher language abilities were more likely to shift from negative emotion to verbal or preverbal vocalization following parent response. Implications of the results for understanding the parent–toddler communication processes that support both emotional development and verbal development are discussed.
Growth behavior of TiB2 hexagonal plates prepared via a molten‐salt‐mediated carbothermal reduction
Authors: Song Shaolei , Zhang Tong , Xie Chen , Zhou Jianmin , Li Rong , Zhen Qiang
Published: September 2019

TiB2 powders were successfully synthesized by a molten‐salt‐mediated carbothermal reduction method. The products obtained at 1300°C for 2 hours were hexagonal plates with side length of 3‐8 μm and thicknesses of 200‐500 nm. The microstructural evolution with temperature confirmed that the growth of TiB2 hexagonal plates was a layer‐by‐layer growth controlled by a two‐dimensional nucleation. No‐uniform grains were observed attached on side and step edges of TiB2 plates, which became finer and disappeared during the growth. This indicated that layer growth and growth on the side of TiB2 plates followed the surface adsorption growth model.
Impact of new hypertension guidelines on target organ damage screening in a Shanghai community‐dwelling population
Authors: Wang Qian , Chao Huijuan , Zheng Shuping , Tan Isabella , Butlin Mark , Avolio Alberto , Zuo Junli
Published: September 2019

Recently, the 2017 ACC/AHA released new hypertension guidelines and proposed a redefinition of hypertension from 140/90 to 130/80 mm Hg. This study assesses the impact of the lower threshold for hypertension diagnosis on the association of hypertension with target organ damage (TOD). Health checks were conducted in a community‐dwelling population in Shanghai in 2017 (N = 10 826; 43.26% mean, age 62 ± 12 years [range 29‐95 years]). Subclinical TOD indices were quantified in terms of left ventricular hypertrophy (LVH) by electrocardiogram (Sokolow‐Lyon standard), estimated glomerular filtration rate (eGFR), and presence of proteinuria. Information on clinical TOD was obtained by questionnaire. Arteriosclerotic cardiovascular disease (ASCVD) was determined by the 2013 ACC/ AHA recommended guidelines. Compared to the higher threshold (140/90 mm Hg), the lower threshold (130/80 mm Hg) was associated with variable rates of increased detection of hypertension and TOD: (a) Hypertension: incidence of hypertension, 29.5% (51.8%‐81.5%) increase in persons with hypertension if the threshold of 130/80 mm Hg is used; (b) Subclinical TOD: LVH, 20.8%; eGFR (30‐60 mL/min per 1.73 m2), 23.7%; proteinuria, 23.5%; (c) Clinical TOD: chronic kidney disease (CKD) IV (eGFR＜30 mL/min per 1.73 m2), 3.1%; diabetes (fasting glucose ≥7.0 mmol/L or HbA1C＞7.0%), 24.3%; stroke, 26.4%; chronic heart disease, 28.1%; acute myocardial infarction, 19.5% (69.4% to 88.9% of total of 36); ASCVD ≥10%, 29.3%. The lower threshold was associated with a significantly higher detection rate of clinical and subclinical TOD of approximately 20% compared to the higher threshold. 15%‐20% of TOD and 29% of ASCVD were also found below the lower threshold of hypertension.
Skin cancer protective behaviors among welders of west of Iran: Importance of access to protective equipment
Authors: Roydel Masoomeh , Harooni Javad , Shariatinia Sedigheh , Karimzadeh Shirazi Kambiz
Published: September 2019

Background

Welders are normally at risk of skin cancer due to continuous contact with natural ultraviolet rays and welding radiation. Protective behaviors against the radiations are the most fundamental measures taken to prevent skin cancer in these individuals.

Aims

This research aimed to evaluate the factors affecting the protective behaviors in welders.

Patients/Methods

In this cross‐sectional research, participants were selected by the census method, and the research tool was a reliable and valid questionnaire filled by 154 welders in Yasuj, Iran. Data analysis was performed in SPSS version 16 using ANOVA, Pearson's correlation coefficient, and independent t test.

Results

The highest age frequency was related to the age‐group of 36‐45 years, and the highest frequency of work experience was less than 10 years. In terms of the level of education, most welders had a diploma or a higher degree. In addition, most behaviors reported included using gloves, whereas the least applied method was using sunscreen cream, the most important cause of which was the high cost of the cream. In this regard, the Pearson's correlation coefficient demonstrated a negative association between skin cancer and job difficulty. In addition, performing of protective behaviors decreased in the target group by aging.

Conclusion

Given the unfavorable mean skin cancer protective behaviors in the welders, it is recommended that interventions, such as planned education, access to protective tools, and periodic skin examinations by a physician, be carried out to promote the health of these individuals and facilitate performing protective behaviors.
Investigating variability and behaviour of Colletotrichum gloeosporioides strains from lesions of coffee blister spot
Authors: Pereira Lucas Fidelis , de Souza Elaine Aparecida , Pereira Fernanda Aparecida Castro , Gonçalves Flávia Maria Avelar
Published: September 2019

Coffee blister spot has been associated with species from the Colletotrichum genus, but there is no information on the variability of isolates present on leaf lesions. This study evaluated a population of Colletotrichum gloeosporioides strains from blister spot lesions in Coffea arabica. Colletotrichum spp. isolates were collected from blister spot lesions on leaves of coffee trees from Catuaí and Topázio cultivars (Coffea arabica). Monosporic cultures were obtained from colonies with sporulation. A pathogenicity test was carried out by inoculation of pathogens on the leaves of young coffee plants. C. gloeosporioides strains were characterized by morphologial, cytological and physiological analyses. The molecular analysis was carried out using Inter‐Retrotransposon Amplified Polymorphism (IRAP) markers. C. gloeosporioides strains showed no pathogenicity on coffee plants and presented a wide variability in all traits evaluated. The presence of sexual strains, formation of CATs (conidial anastomosis tubes) among conidial strains and high mycelial compatibility among strains observed suggest the occurrence of sexual and asexual recombination. The role of these C. gloeosporioides strains on the lesions of coffee plant leaves is unclear.
Metabolisable energy intake and growth of privately owned growing dogs in comparison with official recommendations on the growth curve and energy supply
Authors: Klein Carmen , Thes Melanie , Böswald Linda F. , Kienzle Ellen
Published: September 2019

The correct assumption of metabolisable energy (ME) requirement is essential for the nutrition consultation and diet formulation. In young dogs, too high energy supply can accelerate growth and thus lead to developmental orthopaedic diseases. The aim of the present study was to collect the data on ME intake and body weight (BW) development in privately owned growing dogs in order to compare these data with the current recommendations. Our hypothesis was that the actual ME intake of healthy young dogs would be lower than the actual recommendation. The data of 493 privately owned puppies (median age at first consultation 21 weeks, the median expected mature BW 30 kg) on ME intake, actual and expected mature BW were collected and compared with recommendations of the Society of Nutrition Physiology (GfE, Meyer and Zentek and NRC). In 243 dogs, there was a follow‐up. The actual BW did not deviate systematically from the calculated expected BW (R2 = .929). The ME intake significantly decreased with age (p < .05) and significantly increased with expected mature BW (p < .05). There was no significant interaction between these two parameters (p > .05). Sex had no effect on the ME intake (p > .05). The ME intake of young dogs with a history of skeletal problems or of food allergy did not differ systematically from healthy dogs of similar age and expected mature BW. The ME intake was considerably below NRC recommendations, especially in younger puppies (>8–17 weeks: 78%, >17–26 weeks: 83% of NRC recommendation). A predictive linear equation for ME intake was developed: ME intake (MJ) = (1.063 − 0.565 × [actual BW/expected mature BW]) × actual BW0.75.
Contrasting Mixotrophic Lifestyles Reveal Different Ecological Niches in Two Closely Related Marine Protists
Authors: Wilken Susanne , Choi Chang Jae , Worden Alexandra Z.
Published: September 2019

Many marine microbial eukaryotes combine photosynthetic with phagotrophic nutrition, but incomplete understanding of such mixotrophic protists, their functional diversity, and underlying physiological mechanisms limits the assessment and modeling of their roles in present and future ocean ecosystems. We developed an experimental system to study responses of mixotrophic protists to availability of living prey and light, and used it to characterize contrasting physiological strategies in two stramenopiles in the genus Ochromonas. We show that oceanic isolate CCMP1393 is an obligate mixotroph, requiring both light and prey as complementary resources. Interdependence of photosynthesis and heterotrophy in CCMP1393 comprises a significant role of mitochondrial respiration in photosynthetic electron transport. In contrast, coastal isolate CCMP2951 is a facultative mixotroph that can substitute photosynthesis by phagotrophy and hence grow purely heterotrophically in darkness. In contrast to CCMP1393, CCMP2951 also exhibits a marked photoprotection response that integrates non‐photochemical quenching and mitochondrial respiration as electron sink for photosynthetically produced reducing equivalents. Facultative mixotrophs similar to CCMP2951 might be well adapted to variable environments, while obligate mixotrophs similar to CCMP1393 appear capable of resource efficient growth in oligotrophic ocean environments. Thus, the responses of these phylogenetically close protists to the availability of different resources reveals niche differentiation that influences impacts in food webs and leads to opposing carbon cycle roles.
Pharmacokinetics of a modified, compounded theophylline product in dogs
Authors: Cavett Carrie L. , Li Zhong , McKiernan Brendan C. , Reinhart Jennifer M.
Published: September 2019

Theophylline is a commonly used bronchodilator drug for treatment of chronic canine bronchitis, but no formulations validated in dogs are currently available. An oral, modified and compounded theophylline product (MCT), which could fulfil this need, is available through a USP‐compliant, veterinary compounding pharmacy; however, its pharmacokinetic properties are unknown. The aim of this study was to determine the pharmacokinetics of MCT. Plasma drug concentrations were measured in seven healthy, fed dogs after single doses of intravenous aminophylline (8.6 mg/kg theophylline equivalent) and oral MCT (10 mg/kg). Systemic bioavailability of the MCT was 96.2 ± 32.9%. MCT times to maximum concentration, mean absorption time and terminal half‐life were 8.85 ± 3.63, 6.95 ± 3.42, and 8.67 ± 1.62 hr, respectively. Based on simulations of 10 mg/kg and 12‐hr dosing, steady‐state plasma theophylline concentrations are expected to exceed the minimum therapeutic concentration for 71.7 ± 35.6% of the dosing interval. Overall, the MCT product investigated showed similar pharmacokinetic characteristics compared to previously validated extended‐release theophylline products. An oral dose of 10 mg/kg q 12 hr is likely an appropriate dosage to begin therapy; however, therapeutic drug monitoring may be warranted because of inter‐individual variation.
Fast bridge deflection monitoring through an improved feature tracing algorithm
Authors: Yu Shanshan , Zhang Jian
Published: September 2019

Completely non‐contact and fast measurements are still the focus of vision‐based monitoring in real‐bridge applications. Overall, a fast deflection measurement method, that traces the natural features of structures instead of artificial targets, was developed in this study. More specifically, due to the tiny scale change between images and the small deformation level of small and medium bridges, a simplified fast‐Hessian detector and a pre‐purification‐based RANdom Sampling Consistency (RANSAC) were proposed and verified by performing experiments under different illuminations. The non‐target deformation measurement method based on an improved algorithm was applied to field testing of an arch bridge with 100 m main girder and showed better processing speed and sub‐pixel accuracy than their originals. The optical results obtained by an industrial camera were consistent with other contact‐type sensors, such as level gauges and inclinometers.
Characterization of the gen locus involved in β‐1,6‐oligosaccharide utilization by Enterococcus faecalis
Authors: Grand Maxime , Aubourg Marion , Pikis Andreas , Thompson John , Deutscher Josef , Hartke Axel , Sauvageot Nicolas
Published: September 2019

The bicistronic genBA operon (formerly named celBA) of the opportunistic pathogen Enterococcus faecalis, encodes a 6‐phospho‐β‐glucosidase (GenA) and a phosphotransferase system permease EIIC (GenB). It resembles the cel operon of Streptococcus pyogenes, which is implicated in the metabolism of cellobiose. However, genBA mutants grew normally on cellobiose, but not (genA) or only slowly (genB) on gentiobiose and amygdalin. The two glucosides were also found to be the main inducers of the operon, confirming that the encoded proteins are involved in the utilization of β‐1,6‐ rather than β‐1,4‐linked oligosaccharides. Expression of the genBA operon is regulated by the transcriptional activator GenR, which is encoded by the gene upstream from genB. Thermal shift analysis showed that it binds gentiobiose‐6′‐P with a Kd of 0.04 mM and with lower affinity also other phospho‐sugars. The GenR/gentiobiose‐6′‐P complex binds to the promoter region upstream from genB. The genBA promoter region contains a cre box and gel‐shift experiments demonstrated that the operon is under negative control of the global carbon catabolite regulator CcpA. We also show that the orphan EIIC (GenB) protein needs the EIIA component of the putative OG1RF_10750‐OG1RF_10755 operon situated elsewhere on the chromosome to form a functional PTS transporter.
Two new species of Gloniopsis (Hysteriales, Ascomycota) from clinical specimens: Morphological and molecular characterisation
Authors: Valenzuela‐Lopez Nicomedes , Magaña‐Dueñas Viridiana , Cano‐Lira José F. , Wiederhold Nathan , Guarro Josep , Stchigel Alberto M.
Published: September 2019

Background

The coelomycetes comprise a wide range of fungal species distributed in at least three different classes of the phylum Ascomycota. These are morphologically characterised by producing their conidia inside of fruiting bodies called pycnidia or acervuli, and only a reduced number of species are able to cause human infections. However, their identification in the clinical laboratory is often difficult, due to their few morphological features or because they remain sterile.

Materials and Methods

In the present study, three isolates of coelomycetes of clinical origin were phenotypically and molecularly studied, by sequencing the D1‐D2 fragment of the 28S nuclear ribosomal RNA (nrRNA) (LSU), the internal transcribed spacer region (ITS1‐5.8S‐ITS2) and a fragment of the translation elongation factor 1‐alpha (tef1) genes.

Results and Conclusions

As result of the molecular analysis, the isolates were identified as belonging to the genus Gloniopsis (order Hysteriales, Dothideomycetes) but without the characteristics of any of the species described so far. Therefore, we propose the new species Gloniopsis percutanea and Gloniopsis pneumoniae. Furthermore, this study revealed that some isolates from clinical specimens identified previously as Rhytidhysteron spp. were misidentified, and considering the few studies in the order Hysteriales and the scarce number of sequences of phylogenetic markers, future revisions of this order should be performed to clarify their taxonomy and obtain a better identification from isolates involved in human mycoses.
Coagulative function assessed preoperatively via the clot formation and lysis assay as a prognostic factor for blood loss in adolescents undergoing posterior spinal fusion for idiopathic scoliosis
Authors: Fernandez Allison M. , Neustadt Jeffrey B. , Hahn Gregory V. , Nguyen Anh Thy H. , Amankwah Ernest K. , Goldenberg Neil A.
Published: September 2019

Background

Posterior spinal fusion for adolescent idiopathic scoliosis is a complex surgery often associated with clinically significant blood loss leading to perioperative blood transfusion. Knowledge of risk factors for blood loss and transfusion stems mostly from retrospective studies.

Aim

We sought to prospectively investigate putative prognostic factors for intraoperative blood loss and perioperative blood transfusion in adolescent idiopathic scoliosis patients undergoing posterior spine fusion, including clinical characteristics, surgical factors, and preoperative assessment of overall coagulative and fibrinolytic functions in plasma using the clot formation and lysis (CloFAL) assay.

Methods

Following Internal Review Board approval, adolescents 10 to <21 years old with idiopathic scoliosis undergoing posterior spine fusion were enrolled preoperatively in a single‐institutional prospective cohort and biobanking study. Clinical data were collected on patient characteristics, surgical approach, perioperative management, intraoperative estimated blood loss, and blood transfusion through hospital discharge. Coagulative and fibrinolytic functions in plasma were measured on preoperative samples by CloFAL assay (Coagulation Index and modified Fibrinolytic Index). Univariate linear regression and multivariable linear regression were performed to identify predictors of weight‐indexed intraoperative estimated blood loss EBL (EBL/kg).

Results

The final study population included 74 patients. Median age was 14.8 years (SD = 2.2). After adjustment for other putative prognostic factors via multivariable linear regression, coagulative function as determined preoperatively by CloFAL Coagulation Index was an independent predictor of intraoperative (EBL)/kg. Specifically, each 10% increase in CloFAL CI was associated with 3% decrease in the geometric mean of EBL/kg (OR 0.97, 95%CI 0.94‐0.99, P = .01).

Conclusion

In adolescents undergoing posterior spinal fusion for idiopathic scoliosis, increased coagulative function measured preoperatively using the CloFAL assay is independently associated with decreased intraoperative blood loss. Future studies should expand upon these investigations of plasma coagulative and fibrinolytic capacities in combination with clinical factors, to guide precise preventive strategies against blood loss and blood transfusion in this patient population.
Pediatric intestinal transplantation: Analysis of the intestinal transplant registry
Authors: Raghu Vikram K. , Beaumont Jennifer L. , Everly Matthew J. , Venick Robert S. , Lacaille Florence , Mazariegos George V.
Published: September 2019

The ITR serves as an international database for centers around the world to contribute to current knowledge about intestinal transplant outcomes. Led by the IRTA and managed by the Terasaki Research Institute, the ITR collects data annually and uses these data to generate reports that guide management strategies and policy statements. The aim of this manuscript was to analyze outcomes specific to pediatric intestinal transplantation. Outcome data for children transplanted from 1985 to 2017 were analyzed and predictive factors assessed. A total of 2010 children received 2080 intestine containing allografts during this period. Overall, 1‐year and 5‐year patient and graft survival were 72.7%/66.1% and 57.2/48.8%, respectively. One‐year conditional survival was most strongly associated with being a first‐time transplant recipient and liver‐inclusive grafts. Patient survival was most strongly associated with elective status of transplantation as compared with hospitalized status. Enteral autonomy following transplantation has continued to improve by era with colonic inclusion demonstrating additional incremental improvement in enteral autonomy and freedom from intravenous fluid. While PTLD and technical complications contribute less to graft loss than in earlier eras, rejection remains the largest contributor to long‐term graft loss. Re‐transplantation is linked with significantly worse conditional graft survival, and sepsis remains the largest contributor to patient death. Newer data elements are focusing on impact of donor variables, donor and recipient tissue typing, and impact of the development of de novo antibodies.
Optimal Fluctuation Regulation Method in Low-Speed Digital Piston Pump
Authors: Yu Licheng , Shi Guanglin
Published: September 2019

In digital displacement pump (DDP), the states of valves are nonlinear correlation with the instantaneous flow rate and flow fluctuation. For low-speed working condition, the digital valve has potential to switch several times to improve flow fluctuation. So, the relationship between the valve states and the flow rate is decoded, and a novel optimal fluctuation regulation (OFR) method including OFR-strict (OFR-S) and OFR-relaxation (OFR-R) is designed in this paper. The periodicity and the symmetry of OFR methods are proved and an optimal solution in the predefined minimum characteristic interval (MCI) is realized. Compared to the traditional sequential, partial, and pulse width modulation (PWM) methods, OFR-S has the minimum flow fluctuation, while OFR-R is preferred in low-speed ratio to reduce the digital valve switching frequency. At last, the effects of valve delay and oil compressibility are analyzed. As a theoretical precise optimal solution, OFR method demonstrates its ability in handling nonlinear problems in MCI. And it definitely will be a good base for the nonlinear controller design in the future.
Cicada-inspired self-cleaning superhydrophobic surfaces
Authors: Oh Junho , Yin Sabrina , Dana Catherine E. , Hong Sungmin , Roman Jessica K. , Jo Kyoo Dong , Chavan Shreyas , Cropek Don , Alleyne Marianne , Miljkovic Nenad
Published: September 2019

Water-based heat transfer surfaces in HVAC&R (Heating, Ventilation, Air Conditioning and Refrigeration) systems have biofouling or microbial growth which might not only impose adverse effects to public health but also deteriorate the heat transfer performance of surfaces. In nature, a living creature is surviving while being exposed to formidable condition such as bacteria and fungi. Cicada wing has known to have multi-functional wings exhibiting nonwetting, and anti-microbial due to nanoscale pillars and biochemicals to achieve non-wetting characteristics. We conducted experiments on cicada wings and cicada-inspired engineered superhydrophobic samples to show that droplets jumping from superhydrophobic wings could carry away individual particles (~100 µm) or cluster of particles. This study was investigated on self-cleaning mechanism using jumping droplet condensation and elucidate further antifouling characteristics of non-wetting heat transfer surfaces.
Nonaxisymmetric Study of Tip Leakage Flow in a Centrifugal Compressor With a Volute During Stall Process
Authors: Yang Ce , Su Botai , Fu Li , Zhang Hang
Published: September 2019

Tip leakage flow (TLF) patterns, which affect compressor performance, are closely related to compressor stability. To date, minimal attention has been given to circumferential nonuniformity of the TLF in a centrifugal compressor with a nonaxisymmetric volute structure. In this study, the circumferential difference of the TLF in a centrifugal compressor with a volute during the stall process is analyzed. The circumferential nonuniformity of tip leakage vortex (TLV) trajectories, loading distribution near the tip, and distance between the TLV core and the leading edge (LE) of splitter blades were also investigated. It is shown that in the circumferential direction, there are two peaks associated with the angle (α) between the TLV trajectory of the seven main blades and the axial direction. As the stall process progresses, the blade whose LE is affected by the high static pressure band (PP) induced by the volute tongue (VT) loses its work capacity first and the α difference between this blade and the other blades increases. In addition, the tip loading and TLF velocity of the blade whose LE is affected by the high static pressure band induced by the VT are at a minimum, and the flow loss in the tip clearance is higher. There is a phenomenon of the TLV breakdown. When the blade trailing edge (TE) is located in the low static pressure region, TLV streamlines appear as a significant turn at the breakdown point. However, the TLV streamlines at other circumferential positions do not exhibit this phenomenon.
A Friction–Wear Correlation for Four-Ball Extreme Pressure Lubrication
Authors: Chan Chung-Hung , Lim Wen Huei , Yeong Shoot Kian , Kow Kien Woh , Ho Yong Kuen
Published: September 2019

A first-ever friction–wear model for four-ball extreme pressure (EP) lubrication is developed in this work based on 12 oil samples comprising minerals, esters, and other formulated lubricants. The model considers the rate of entropy generation and dissipation within the lubricated tribosystem to describe the interaction between the friction and the wear behaviors at extreme pressure conditions. The model can be used to calculate the probability to pass or fail at a specific load to estimate the weld point of a lubricant. The calculated probability exhibited a similar trend as a load-wear index from the ASTM D2783 EP test method. Besides, the model is able to estimate the EP performance of an unknown lubricant based on the model parameter, namely the dissipative coefficient. This parameter describes the proportionality between the friction and the wear phenomena from the perspective of thermodynamic analysis. This work provides useful tools to better understand the fundamentals of EP lubrication and to characterize the lubricants without overly relying on tribotest machines.
In Situ Identification of Natural Frequency Branches in Gyroscopic Systems via Autoresonance and Phase-Locked Loop
Authors: Davis Solomon , Tresser Shachar , Ariel Netanel , Ferdinskoif Alex , Bucher Izhak
Published: September 2019

The methods described allow one to directly measure the individual branches of the Campbell diagram of a physical gyroscopic system at any rotation speed. Typically, such data are acquired by exciting the vibration modes through naturally occurring unbalance forces. During run-up, these forces expose some of the Campbell diagram, but mainly the forward whirling branches, leaving the backward whirling branches mostly hidden. Furthermore, good modal frequency data are only acquired at critical speeds. The methods proposed here allow one to excite either a forward or backward whirling mode at any rotation speed in a precisely controlled manner, greatly improving the quality of an acquired Campbell diagram. The technique employs an external excitation device that automatically produces oscillating forces at a chosen modal frequency. Control is based on the autoresonance feedback algorithm, which can excite a mechanical system at resonance effectively. It will also be shown that with two actuators and two sensors, one can choose which bending mode to excite at resonance in either the forward or backward whirling direction. As the rotation speed is then gradually increased, one can measure the speed dependence of the resonance frequency. Furthermore, when combining autoresonance with a phase-locked loop, one can acquire very clean measurements by removing most of the noise generated by the unbalance and other sources. The technique is demonstrated analytically, numerically, and experimentally.
Efficiency Assessment of an Evacuated U-Tube Solar Collector Using Silver Nanofluid
Authors: Kaya Hüseyin , Eltugral Nurettin , Kurukavak Ali , Arslan Kamil
Published: September 2019

A water-based silver nanofluid (Ag/PW) was prepared from gelatin-stabilized silver nanoparticles (Ag NPs) of about 15 nm and further used as a working fluid in an evacuated U-tube solar collector (EUSC) to investigate the variation in the collector efficiency. An Ag/PW nanofluid having 0.035 wt% was prepared and demonstrated a good promise of colloidal stability when dispersed in pure water. Collector efficiency measurements were carried out at outdoor conditions with four different mass flow rate values (0.063, 0.051, 0.033, and 0.02 kg/s). Results showed that Ag/PW have superior heat transfer properties than that of pure water as the base fluid. It was found that the efficiency of the collector was directly proportional to the mass flow rate of the working fluid until an optimum value was attained. Experimental results show that the highest collector efficiency was 72.2% at 0.051 kg/s mass flow rate, which is 21.3% higher than that of the pure water.
On the Liftoff of Diffusion Flame: An Experimental and Analytical Study
Authors: Akbarzadeh Mohsen , Birouk Madjid
Published: September 2019

The effect of lip thickness of fuel nozzle on the liftoff of an attached diffusion methane flame with and without a coflow was experimentally and analytically investigated. Three fuel nozzles made of a long pipe with the same internal diameter but different nozzle lip thickness were tested. The co-airflow was also varied to assess its impact on the liftoff of jet diffusion flame. The results showed that the effect of fuel nozzle lip thickness on the liftoff of a free jet flame (i.e., no coflow) is marginal. However, the presence of a weak to moderate coflow (0.05 m/s < Uco < 0.3 m/s) reduced the liftoff velocity of an attached flame. The reduction rate of the liftoff velocity with co-airflow was found to be more significant for the fuel nozzle with the smaller lip thickness. At a relatively higher coflow (Uco > ∼0.3 m/s), a more pronounced drop in the liftoff velocity with coflow was observed. Flow field characteristics obtained using PIV measurements showed that the coflow stream experienced a transition to the turbulent regime for Uco > ∼0.3 m/s range which is believed to cause the inception of the flame liftoff to occur. A model for predicting the liftoff velocity of an attached flame in the presence of a coflow was developed based on the stoichiometric mixture velocity equation. This model showed good agreement with the present experimental data. However, although it can predict successfully the observed trends in the literature, further experiments are required to generalize it.
Quantifying and Qualifying Alloys Based on Level of Homogenization: A U-10Mo Alloy Case Study
Authors: Wang Chao , Xu Zhijie , Fagan Deborah , Field David P. , Lavender Curt , Joshi Vineet V.
Published: September 2019

Homogenization heat treatment is performed to attain uniformity in microstructure which is helpful to achieve the desired workability and microstructure in final products and, eventually, to gain predictive and consistent performance. Fabrication of low-enriched uranium alloys with 10 wt% molybdenum (U-10Mo) fuel plates involves multiple thermomechanical processing steps. It is well known that the molybdenum homogeneity in the final formed product affects the performance in the nuclear reactor. To ensure uniform homogenization, a statistical method is proposed to quantify and characterize the molybdenum concentration variation in U-10Mo fuel plates by analyzing the molybdenum concentration measurement data from scanning electron microscopy energy dispersive spectroscopy line-scan. Statistical tolerance intervals (TI) are employed to determine the qualification of the U-10Mo fuel plate. We formulate an argument for the minimum number of independent samples to define fuel plate qualification if no molybdenum measurement data are available in advance and demonstrate that the given TI requirements can be equivalently reduced to a sample variance criterion in this application. The outcome of the statistical analysis can be used to optimize casting design and eventually increase productivity and reduce fabrication costs. The statistical strategy developed in this paper can be implemented for other applications especially in the field of material manufacturing to assess qualification requirements and monitor and improve the process design.
Frictional Characteristics and Electrical Conductivity of Electrical Sliding Contacts With Circular Grooved Porous Disk Under Lubricated Conditions
Authors: Kaneko Satoru , Taura Hiroo , Taira Masahiro , Luu Van Manh
Published: September 2019

In this study, porous materials were applied to the surface materials of electrical sliding contacts to produce long and stable operations. The proposed sliding contacts consist of a rotating circular grooved porous disk and a stationary rider having a spherical surface. We conducted the experimental analysis from two perspectives. The first perspective was to inspect the effect of the design parameters on the electrical conductivity and the frictional characteristics; this was done by performing tests under various loads applied on the sliding contacts. The second perspective was to investigate the durability and stability of the sliding contacts by using the tests for a long operating time under a constant applied load. Our experimental results proved that the porous disk generated a lower and a more stable contact voltage and frictional force than the conventional nonporous solid disk. This effect is significant when a large curvature radius of grooves is provided on the disk surface. These results are attributable to the reduction of the hydrodynamic fluid force by the porous material and the grooves; the porous material yields lower hydrodynamic pressure due to the seepage of the lubricant oil across the interface between the oil film and the porous matrix and the grooves enhance the reduction of the hydrodynamic effect because of oil leakage to the downstream region. These factors reduce the oil film thickness between the disk and rider and facilitate the metal contact, and thereby a porous grooved disk generates higher electrical conductivity than a conventional solid disk.
Thermal Expansion Induced Neutrality of a Circular and an Annular Elastic Inhomogeneity
Authors: Song K. , Song H. P. , Schiavone P. , Gao C. F.
Published: September 2019

An elastic inhomogeneity is termed neutral if its introduction does not disturb the original stress field in the initially uncut elastic body. Neutrality in this sense is often achieved by appropriate design criteria such as a careful choice of the shape of the inhomogeneity and the properties of the interfacial layer between the inhomogeneity and its surrounding matrix. Unfortunately, mismatched stress and strain fields in the resulting composite structure make it difficult to simultaneously control both the shape of the inhomogeneity and its interfacial properties to achieve the desired neutrality property. We assert that the associated temperature field can be used to adjust the stress and strain fields within the inhomogeneity via thermal expansion, thus allowing us to control the properties of the interfacial layer for a given shape of inhomogeneity. Our theoretical results show that the design of a neutral circular or annular elastic inhomogeneity requires an accompanying internal uniform temperature field when the elastic body is in equi-biaxial tension and an internal temperature field which is quadratic if the body is subjected to uniaxial tension or shear force. More importantly, in contrast to the well-established result in the literature for a purely elastic inhomogeneity, under certain conditions, a neutral elastic inhomogeneity can be designed via thermal expansion despite the assumption of a perfectly bonded interface between the inhomogeneity and the surrounding matrix.
Mode II Fracture of an Elastic-Plastic Sandwich Layer
Authors: Martínez-Pañeda Emilio , Cuesta I. Iván , Fleck Norman A.
Published: September 2019

The shear strength of a pre-cracked sandwich layer is predicted, assuming that the layer is linear elastic or elastic-plastic, with yielding characterized either by the J2 plasticity theory or by a strip-yield model. The substrates are elastic and of dissimilar modulus to that of the layer. Two geometries are analyzed: (i) a semi-infinite crack in a sandwich layer, subjected to a remote mode II K-field and (ii) a center-cracked sandwich plate of finite width under remote shear stress. For the semi-infinite crack, the near-tip stress field is determined as a function of elastic mismatch, and crack tip plasticity is either prevented (the elastic case) or duly accounted for (the elastic-plastic case). Analytical and numerical solutions are then obtained for the center-cracked sandwich plate of the finite width. First, a mode II K-calibration is obtained for a finite crack in the elastic sandwich layer. Second, the analysis is extended to account for crack tip plasticity via a mode II strip-yield model of finite strength and finite toughness. The analytical predictions are verified by finite element simulations, and a failure map is constructed in terms of specimen geometry and crack length.
Improved ion imaging of slowly dried neurons and skin cells by graphene cover in time-of-flight secondary ion mass spectrometry
Authors: Lee Sun Young , Lim Heejin , Moon Dae Won , Kim Jae Young
Published: September 2019

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful tool to obtain both chemical information and spatial distribution of specific molecules of interest on a specimen surface. However, since the focused ion beam requires ultrahigh vacuum conditions for desorption and ionization of analytes, proper specimen preparation, such as drying, freeze-drying, and frozen dehydration, is required for ToF-SIMS analysis. In particular, biological specimens with high moisture content generally have a problem of specimen deformation during the normal drying process for a vacuum environment. In this study, the authors propose a cellular specimen preparation method to improve the ion imaging of cells by reducing the deformation of specimens in ToF-SIMS analysis. When the cells on the slide substrate are completely covered with single-layer graphene, the ToF-SIMS imaging is improved by reduced cell deformation due to slow drying. In addition, the graphene encapsulation also induces a reduction in the yield of secondary ions, thereby suppressing the background ion spectra generated by the unwanted organic residues on the substrate, resulting in the improvement of ToF-SIMS imaging. The authors also found that adding plasma treatment to this sample preparation can further improve ion imaging of cells. After cell dehydration is completed, the covered graphene layer can be peeled off by air-plasma treatment and the unwanted organic residues on the substrate can be removed due to plasma cleaning, thereby much improving ion imaging of cells.
Variation of the apparent size of the Sun visualized with basic photographic equipment
Authors: Trillenberg Peter
Published: September 2019

Due to the elliptic shape of Earth's orbit around the Sun, the apparent diameter of the Sun varies throughout the year. With digital analysis of a number of images at a given date, the effect can be demonstrated with a digital single lens reflection camera (DSLR) and a standard telephoto lens even over a few days. In the analysis, the influence of image brightness and atmospheric refraction on apparent Sun size and shape have to be removed to reach the accuracy that is required.
Interception! A decoy scaffold disrupts autoimmunity
Authors: Weaver Jessica D.
Published: September 2019

Subcutaneous implantation of microporous collagen scaffolds decorated with a model autoantigen prevents onset of autoimmune encephalomyelitis in mice.
Draft Genome Sequence of Multidrug-Resistant Proteus mirabilis CKTH01, Isolated from Raw Chicken Meat
Authors: Areekit Supatra , Thongpramul Nuttida , Yamprayoonswat Wariya , Jumpathong Watthanachai , Sittihan Satapanawat , Wanthongchareon Suwanan , Ruangsuj Pattarawan , Wachiralurpan Sirirat , Chansiri Kosum , Yasawong Montri
Published: September 2019

Proteus mirabilis
CKTH01 is a pathogenic bacterium isolated from raw chicken meat. The genome sequence of
P. mirabilis
CKTH01 contains genes encoding multidrug efflux pumps, which are the virulence factors of the antibiotic-resistant bacterium. This 3.98-Mb draft genome sequence of
P. mirabilis
CKTH01 will contribute to the understanding of the distribution of multidrug-resistant
P. mirabilis
in raw chicken meat at the open markets.