bluuebunny/crossref_metadata_2025 huggingface dataset:
A score system to predict no‐reflow in primary percutaneous coronary intervention: The PIANO Score
Authors: Dai Chunfeng , Liu Muyin , Zhou You , Lu Danbo , Li Chenguang , Chang Shufu , Chen Zhangwei , Qian Juying , Ge Junbo
Published: October 2021

Background

Angiographic no‐reflow is associated with poor outcomes in patients with ST‐segment elevation myocardial infarction (STEMI). We sought to develop and validate a score system to predict angiographic no‐reflow in primary percutaneous coronary intervention (PCI).

Methods

ST‐segment elevation myocardial infarction patients undergoing primary PCI were consecutively enrolled and were randomly divided into the training and validation set. Angiographic no‐reflow was defined as thrombolysis in myocardial infarction (TIMI) flow grade 0 to 2 after PCI. In the training set, independent predictors were identified by logistic regression analysis, and a score system (PredIction of Angiographic NO‐reflow, the PIANO score) was constructed based on the β‐coefficient of each variable. The established model was evaluated for discrimination and calibration.

Results

Angiographic no‐reflow occurred in 362 (17.8%) of 2036 patients. Age ≥70 years, absence of pre‐infarction angina, total ischaemic time ≥4 h, left anterior descending as culprit artery, pre‐PCI TIMI flow grade ≤1 and pre‐PCI TIMI thrombus score ≥4 were independent predictors of angiographic no‐reflow. The PIANO score ranged from 0 to 14 points, yielding a concordance index of 0.857 (95% confidence interval: 0.833 to 0.880), with good calibration. In the high‐risk (≥8 points) group, the probability of angiographic no‐reflow phenomenon was 38.7%, while it was only 4.8% in the low‐risk (<8 points) group. The score system performed well in the validation set.

Conclusions

We establish and validate a score system based on six clinical variables to predict angiographic no‐reflow in STEMI patients undergoing primary PCI, which may help choose the optimal individual treatment strategy.
Housing prices and son preference: Evidence from China’s housing reform
Authors: Guo Rufei , Wang Qian , Yi Junjian , Zhang Junsen
Published: October 2021

Do high housing prices reduce the demand for sons? As Chinese parents need to acquire houses for their sons’ marriage, high housing prices increase the cost of sons relative to daughters. We exploit China's housing reform in the 1990s as a natural experiment to identify the effect of housing prices on demand for sons. We find that housing prices have no effect on the probability of having a son at the first birth. High housing prices reduce the probability of having a son at the second birth, especially when the first‐born is a daughter. A 10% increase in housing prices reduces the probability of having a son at the second birth by 0.78 percentage points. The findings remain robust when using aggregate prefecture‐cohort data for the post‐reform period.
Low prevalence of amyloid and tau pathology in drug‐resistant temporal lobe epilepsy
Authors: Silva Juliana C. , Vivash Lucy , Malpas Charles B. , Hao Yong , McLean Catriona , Chen Zhibin , O'Brien Terence J. , Jones Nigel C. , Kwan Patrick
Published: October 2021

Objective

Cognitive impairment is common in patients with chronic drug‐resistant temporal lobe epilepsy (TLE). Hyperphosphorylated tau (pTau) and amyloid‐β (Aβ) plaques, pathological hallmarks of Alzheimer disease, have been hypothesized to play a mechanistic role. We investigated Aβ plaques and pTau prevalence in TLE patients who underwent resective surgery and correlated their presence with preoperative psychometric test scores and clinical factors.

Methods

Patients were retrospectively selected from the epilepsy surgery register of the Royal Melbourne Hospital, Australia. Sections from the resected temporal lobe were immunostained for pTau and Aβ plaques (antibodies: AT8, 1E8). The presence and severity of pathology were correlated with clinical characteristics, and verbal and visual learning functions as measured by the Verbal Pair Associates (VPA) test and Rey Complex Figure Test.

Results

Fifty‐six patients (55% female) aged 20–68 years (median = 34 years) at surgery were included. Aβ plaques were detected in four patients (7%), all at the moderate level. There was no difference in duration, age at onset of epilepsy, or side of resection between patients with and without Aβ plaques. Sparse pTau was found in two patients (3.5%). Both had moderate Aβ plaques and were >50 years of age. Patients with Aβ plaques had a lower median score for the VPA hard assessment compared to those without (0 vs. 4; p = .02). There was otherwise no correlation between pathology and psychometric test scores.

Significance

Aβ plaques and pTau were uncommon in the resected brain tissue of patients who have undergone temporal lobectomy, and did not correlate with clinical characteristics or preoperative psychometric test scores, except for a lower VPA median score in patients with Aβ plaques. Therefore, considering the low prevalence of Aβ plaques and pTau herein observed, it is unlikely that cognitive impairment in TLE is driven by the same mechanisms as in Alzheimer disease.
Nurses' knowledge, concerns, perceived impact and preparedness toward COVID‐19 pandemic: A cross‐sectional survey
Authors: El‐Monshed Ahmed Hashem , Amr Mostafa , Ali Ahmed Salah , Elmasry Yosr Mohamed , Zoromba Mohamed
Published: October 2021

Aim

This study aimed to assess the nurses' knowledge, concerns, perceived impact and preparedness toward the COVID‐19 pandemic.

Background

As COVID‐19 is a new disease, its spread and emergence cause fear, anxiety and confusion among the general population. Nurses are in close contact with infected persons, and their knowledge plays an important role in preventing the transmission chain.

Methods

In this cross‐sectional study, 207 nurses were selected using convenience sampling from 29 March to 19 April 2020. The study used a questionnaire assessing the nurses' baseline characteristics, their source of information, knowledge, concerns, the perceived impact and their preparedness for the COVID‐19 pandemic.

Results

Around half of the surveyed nurses (51.2%) reported that the Ministry of Health's and World Health Organization's websites and official pages were their main sources of information. The majority of nurses (81.6%) knew the nature of the virus, 83.6% agreed that their job puts them at risk of infection with COVID‐19 and 72% felt personally prepared for the pandemic.

Conclusion

The majority of nurses had an acceptable level of knowledge regarding COVID‐19. However, psychological interventions are needed to be addressed in the planning stage before any pandemic.
Formulating Portland cement–reactive alumina blend through thermodynamic modeling to prevent the alkali–silica reaction
Authors: Zhou Jin , Chen Lou , Zheng Keren , Liu Zanqun , Yuan Qiang , He Fuqiang
Published: October 2021

This study aims to formulate solid and aqueous compositions of hydrated Portland cement incorporated with reactive alumina (RA) via thermodynamic modeling, with the goal to prevent alkali–silica reaction (ASR). Based on SEM/EDS point analysis, the uptake of Al into C–S–H was corrected in the thermodynamic modeling to improve the accuracy. The predicted solid and aqueous compositions were validated by means of XRD, TGA, and ICP. An accelerated mortar bar test was also carried out to confirm the ASR mitigating efficiency, and a preliminary relationship among the ASR expansion, solid assemblage, and aqueous species was established. The critical content for RA is around 5.75% in the studied systems, above which katoite precipitates, resulting in increased Al concentration in the pore solution (∼0.8 mmol/L); hence, ASR can be effectively inhibited.
Spring and autumn movements of an Arctic bird in relation to temperature and primary production
Authors: Doyle Susan , Cabot David , Griffin Larry , Kane Adam , Colhoun Kendrew , Bearhop Stuart , McMahon Barry J.
Published: October 2021

It is increasingly important to understand animal migratory movements because climate disruption is shifting plant and animal phenology at different rates across the world. We applied a Markov state‐switching model to telemetry data of a long‐distance migrant, the barnacle goose, to detect migratory movement and relate it to three proximate environmental factors: photoperiod, daily mean temperature and forage plant phenology. Spring migratory movements towards the breeding grounds were most closely related to forage plant phenology (measured by accumulated growing degree days, GDDs); high GDDs values were associated with a greater probability of transiting to a more northerly site, suggesting that spring migration is closely aligned with primary productivity. Autumn migration from the breeding grounds was most closely related to temperature; higher temperature values were associated with a greater probability of remaining settled at the current site, suggesting that autumn migration is closely aligned with atmospheric conditions. Understanding the relative influence of different environmental factors on migratory patterns may in turn provide us with insight into how continued climate disruption could influence northern migratory systems.
Changes in sleep pattern and dream activity across and after the COVID‐19 lockdown in Italy: A longitudinal observational study
Authors: Alfonsi Valentina , Gorgoni Maurizio , Scarpelli Serena , Zivi Pierpaolo , Sdoia Stefano , Mari Emanuela , Quaglieri Alessandro , Ferlazzo Fabio , Giannini Anna Maria , De Gennaro Luigi
Published: October 2021

A large body of evidence has documented the impact of the global COVID‐19 outbreak – and especially the lockdown period – on sleep quality and quantity. Here, we present the first Italian longitudinal study on sleep and COVID‐19 considering four different time points collected during lockdown (from 29 March 2020 to 3 May 2020) and a subsequent follow‐up period (October 2020). We used an online survey to collect socio‐demographic and COVID‐19 related information. Subjects were also asked to complete a sleep diary at each time point of the study. Our longitudinal sample included 147 participants. Statistical comparison across time intervals showed remarkable changes in sleep patterns during and after the lockdown. In particular, during lockdown we observed longer sleep latency, less ease of falling asleep, a higher total bedtime, and a lower dream frequency. The week‐by‐week evaluation described relatively stable patterns in the observed measures during the lockdown period, except for dream frequency, affected by a rapid increase in the early phase of lockdown. Our findings are in line with the current literature. Furthermore, the prospective longitudinal investigation comprising several time points offered the possibility of (a) observing the temporal dynamics and the different entities of such changes over time, and (b) reducing the typical memory bias for these studies.
Non‐profit breastfeeding organisations' peer support provision in areas of socio‐economic deprivation in the UK: A meta‐ethnography
Authors: Hunt Louise , Thomson Gill , Whittaker Karen , Dykes Fiona
Published: October 2021

In many high‐income countries such as the United Kingdom, inequalities in breastfeeding initiation and continuation rates exist, whereby socio‐economically advantaged mothers are most likely to breastfeed. Breastfeeding peer support interventions are recommended to address this inequality, with non‐profit breastfeeding organisations providing such support in areas of deprivation. As these organisations' roots and membership are often formed of relatively highly resourced women who have different backgrounds and experiences to those living in areas of deprivation, it is important to understand their practices in this context. In order to explore how UK non‐profit organisations practice breastfeeding peer support in areas of socio‐economic deprivation, a systematic review and meta‐ethnography of published and grey literature was undertaken. Sixteen texts were included, and three core themes constructed: (1) ‘changing communities’ reveals practices designed to generate community level change, and (2) ‘enabling one to one support’, explains how proactive working practices enabled individual mothers' access to supportive environments. (3) ‘forging partnerships with health professionals’, describes how embedding peer support within local health services facilitated peer supporters' access to mothers. While few breastfeeding peer support practices were directly linked to the context of socio‐economic deprivation, those described sought to influence community and individual level change. They illuminate the importance of interprofessional working. Further work to consolidate the peer‐professional interface to ensure needs‐led care is required.
Veloporphyrellus latisporus (Boletaceae), a new species from moist temperate forests of Pakistan
Authors: Khan Junaid , Ullah Sadiq , Sher Hassan , Fiaz Muhammad , Khalid Abdul Nasir
Published: October 2021

Veloporphyrellus latisporus is proposed as a new species based on morphological characters and supporting molecular data from the ITS and LSU regions of the nuclear DNA. The new species is characterized by its red to reddish brown granulose pileus and comparatively broader basidiospores. A key to the species of Veloporphyrellus is provided. This is the first report of any Veloporphyrellus species from Pakistan.
Comparison between estimated and measured myopia progression in Hong Kong children without myopia control intervention
Authors: Yang Yajing , Cheung Sin Wan , Cho Pauline , Vincent Stephen J
Published: October 2021

Purpose

To compare myopia progression estimated by the Brien Holden Vision Institute (BHVI) Myopia Calculator with cycloplegic measures in Hong Kong children wearing single‐vision distance spectacles over a 1‐ and 2‐year period.

Methods

Baseline age, spherical equivalent refraction (SER) and ethnicity of control participants from previous longitudinal myopia studies were input into the BHVI Myopia Calculator to generate an estimate of the SER at 1 and 2 years. Differences between the measured and estimated SER (116 and 100 participants with 1‐ and 2‐year subjective refraction data, respectively, and 111 and 95 participants with 1‐ and 2‐year objective refraction, respectively) were analysed, and the measured SER compared with the 95% confidence interval (CI) of the estimated SER.

Results

In children aged 7–13 years, 36% progressed within the 95% CI of the Myopia Calculator's estimate, whereas 33% became less myopic than predicted (range 0.31 to 1.92 D less at 2 years) and 31% became more myopic than predicted (range 0.25 to 2.33 D more myopic at 2 years). The average difference between the estimated and measured subjective or objective SER at 1 and 2 years of follow‐up was not clinically significant (<0.25 D).

Conclusions

On average, the BHVI Myopia Calculator estimated SER was in close agreement with measured cycloplegic SER after 1 and 2 years of follow‐up (mean differences < 0.25 D). However, the measured myopia progression only fell within the 95% CI of the estimated SER for 32%–38% of children, suggesting that the BHVI ‘without management’ progression data should be interpreted with caution. The inclusion of additional data, modified to include axial elongation, from longitudinal studies of longer duration with larger sample sizes and a range of racial backgrounds may improve the Calculator's ability to predict future myopia progression for individual children.
A New Technique for Placement of Blocking Screws and its Mechanical Effect on Stability of Tibia Fractures with Distal Fragments after Insertion of Small‐Diameter Intramedullary Nails
Authors: Zhang Cong‐ming , Sun Liang , Wang Qian , Huang Qiang , Lin Hua , Duan Ning , Zhang Chen‐chen , Ma Teng , Xue Han‐zhong , Zhang Kun , Li Zhong
Published: October 2021

Objective

To design a novel blocking screws (BSs) geometry and insertion method to treat distal tibia fracture with nailing and comparison of mechanical properties of novel and traditional screws.

Methods

Twenty‐one synthetic left tibiae were sectioned to obtain 21 distal segments measuring 55 mm. Intramedullary (IM) 9‐mm tibial nails were advanced to 6 mm from the ankle joint. Two transverse and one anterior–posterior (AP) locking screws were inserted. Both medial–lateral (ML) BSs were placed 10 mm from the topmost interlocking screw. A custom‐made jig assisted in placing the novel and traditional BSs. The time spent in placing each BS was recorded. All the samples were repaired with an IM nail and without BSs, with two traditional BSs, and with two novel BSs. An initial loading from −150 to +150 N was applied to specimens in the ML direction at 185 mm from the nail end, followed by cyclic loading of the same for 10,000 cycles with failure‐to‐test loading of 350 N in the ML direction. The maximum displacement was measured at 80 mm from the nail end and recorded under initial loading. The damage of two kinds of BSs to the nail was recorded.

Results

Compared with average 5.21 min of the time of placing a traditional BS, the time spent in positioning a novel BS on the fracture model was 2.53 min. In the distal bone–implant constructs (BICs), the addition of traditional BSs decreased the maximum displacement of the BICs by 26.2%. The addition of the novel BSs decreased the displacement by 28.9%. All constructs survived 10,000 cycles without hardware deformation. The failure rate of the control group was significantly greater than that of the traditional group; however, the novel group was similar to the traditional group. The damage of the traditional BS to the nail was greater than that of the novel one.

Conclusions

The novel and traditional BSs are comparably effective for increasing the primary mechanical stability of distal metaphyseal fractures after nailin. However, compared to the placement of a traditional BS, implanting a novel BS took more less time and caused less damage to the nail. Additionally, the most obvious advantage of the novel BS design and insertion technology was that the pressure and distance between it and the IM nail could be controlled by rotating the screw. These advantages of the novel BS will be beneficial for clinical application.
Testicular appendage torsion in children
Authors: Tanaka Keiichiro , Kato Haruki , Nikai Koki , Mikami Takafumi , Okazaki Tadaharu
Published: October 2021

Background

Testicular appendage torsion (TAT) is a medical emergency that presents as an acute scrotum, usually in children and preadolescents. In previous reports of TAT, most cases have been treated conservatively, but some necessitate surgical treatment. Our aim was to examine the incidence, clinical examination findings, etiology, and treatment of TAT.

Methods

We retrospectively reviewed records of all patients with TAT (aged ≤15 years) treated at the Juntendo University Urayasu Hospital between January 2012 and September 2020. Surgical treatment was performed when a diagnosis of testicular torsion could not be completely ruled out or if pain recurred after conservative treatment. Patients with a hard scrotum or scrotal erythema were hospitalized for conservative treatment. Data regarding age, diagnosis, blood test results, and clinical findings were analyzed.

Results

Among 101 boys with TAT, the median age was 10 years. The incidence of TAT varied significantly according to age and was highest among patients aged 8–11 years. Sixty‐seven boys (66.3%) underwent inpatient surgical treatment, 10 boys (9.9%) received inpatient conservative treatment, and 24 boys (23.8%) received outpatient conservative treatment. The median duration of hospitalization was significantly shorter among those who underwent surgery (2.0 days) than among those who received inpatient conservative treatment group (3.5 days).

Conclusions

Operations were short, uncomplicated, and safe; they shortened the hospital stay; and they would certainly prevent recurrence of TAT and testicular torsion on one side. Furthermore, we recommended that TAT patients presenting with signs of severe inflammation, such as hard scrotum or scrotal erythema, receive early surgical treatment to minimize duration of hospitalization.
Optical Attenuators Extend Dynamic Range but Alter Angular Response of Planar Ultraviolet‐C Dosimeters
Authors: Su Alison , Geldert Alisha , Grist Samantha M. , Herr Amy E.
Published: October 2021

Effective ultraviolet‐C (UV‐C) decontamination protocols of N95 respirators require validation that the entire N95 surface receives sufficient dose. Photochromic indicators (PCIs) can accurately measure UV‐C dose on nonplanar surfaces, but often saturate below doses required to decontaminate porous, multilayered textiles like N95s. Here, we investigate the use of optical attenuators to extend PCI dynamic range while maintaining a near‐ideal angular response—critical for accurate measurements of uncollimated UV‐C. We show analytically that tuning attenuator refractive index, attenuation coefficient, and thickness can extend dynamic range, but compromises angular response unless the attenuator is an ideal diffuser. To investigate this tradeoff empirically, we stack PCIs behind model specular (floated borosilicate) and diffuse (polytetrafluoroethylene) attenuators, characterize the angular response, and evaluate on‐N95 UV‐C measurement accuracy within a decontamination system. Both attenuators increase PCI dynamic range >4×, but simultaneously introduce angle‐dependent transmittance, which causes location‐dependent underestimation of UV‐C dose. PCI‐borosilicate and PCI‐polytetrafluoroethylene stacks underreport true on‐N95 dose by (1) 14.7% and 3.6%, respectively, when near‐normal to the source lamp array, and (2) 40.8% and 19.8%, respectively, in a steeply sloped location. Overall, we demonstrate that while planar attenuators can increase PCI dynamic range, verifying near‐ideal angular response is critical for accurate UV‐C measurements.
MED12 exon 2 and TERT promoter mutations in primary and recurrent breast fibroepithelial lesions
Authors: Hu Yanjiao , Li Guangqi , Wang Lili , Zhang Longxiao , Guan Jingjing , Wang Jigang
Published: October 2021

The genetic alterations in the recurrent breast fibroepithelial tumors are poorly understood. In the present study, we aimed to investigate mediator protein complex subunit 12 (MED12) exon 2 and telomerase reverse transcriptase (TERT) promoter mutations in a series of primary and recurrent fibroepithelial tumors. Sanger sequencing for MED12 exon 2 and TERT promoter was performed in 26 pairs of primary and recurrent fibroepithelial tumors (19 pairs of phyllodes tumors and seven pairs of fibroadenomas). The relationship between the genotypes and clinicopathological variables was also analyzed. MED12 mutation was identified in 19 primary tumors (12 phyllodes tumors and 7 fibroadenomas) and 17 recurrences (14 phyllodes tumors and three fibroadenomas). Most recurrent phyllodes tumors retained the original MED12 variants (17/19). Six recurrent fibroadenomas showed different MED12 variants from their paired primary tumors (6/7). TERT promoter mutation was identified in 13 primary phyllodes tumors (13/19) and 15 recurrent phyllodes tumors (15/19). However, it was only identified in one primary fibroadenoma (1/7). Recurrent phyllodes tumors often retained the original MED12 and TERT promoter mutations, while recurrent fibroadenomas often acquired new MED12 mutations. Our findings suggest that recurrent phyllodes tumors may be “true recurrence,” and TERT mutant “benign fibroepithelial tumors” should be treated as phyllodes tumors.
Survey of the RhD selection and issuing practices for uncrossmatched blood products at pediatric trauma hospitals in the United States: The BEST collaborative study
Authors: Yazer Mark H. , Dunbar Nancy M. , Delaney Meghan ,   the Biomedical Excellence for Safer Transfusions Collaborative
Published: October 2021

Background

As evidence demonstrating the importance of early transfusions in trauma resuscitation accumulates, when RhD‐negative products might not be available, it is important to understand the nature of the RhD‐type of products provided to bleeding pediatric patients of potentially unknown RhD‐type.

Methods

A survey link was electronically sent to the transfusion service medical director and/or laboratory manager at American pediatric Level I and Level II hospitals inquiring about their practices for selecting RhD‐type of uncrossmatched red blood cells (RBC) or low titer group O whole blood (LTOWB) for boys and girls.

Results

There were 55/117 (47.0%) analyzable responses; 43/55 (78.2%) from Level I and 12/55 (21.8%) from Level II hospitals. For in hospital transfusions, 51/55 (92.7%) of centers use only RhD‐negative blood products to resuscitate girls ≤18 years old while 30/55 (54.5%) of centers do the same for boys ≤18 years old. Most centers 41/55(74.5%) store RBCs and/or LTOWB in in‐hospital remote refrigerators; 27 store only RhD‐negative RBCs and 2 store only RhD‐negative LTOWB units in these refrigerators. A total of 24/55 (43.6%) centers have RBCs and/or LTOWB available on road ambulances or helicopters for prehospital transfusion; 12 transport only RhD‐negative RBCs and two transport only RhD‐negative LTOWB. Most centers, 35/55 (63.6%), address the prophylaxis of an RhD‐negative female recipient of RhD‐positive transfusion on a case‐by‐case basis.

Conclusion

While there is some variability, most of the responding pediatric trauma centers routinely utilized RhD‐negative RBCs for emergency transfusion for patients ≤18 years old of unknown RhD‐type.
Qualitative analysis of a mathematical model about population of green turtles on the Galapagos island
Authors: Herrera Candy , Duque Cosme Ramon , Leiva Hugo
Published: October 2021

According to the IUCN, most sea turtles fall into one of the endangered categories. Since, sea turtles, like many other reptiles, present an unusual developmental process, marked by the determination of the sex of the offspring by environmental factors, more specifically by temperature. In the temperature sex determination (TSD) system the temperature of an embryo's environment during incubation period will dictate the embryo's sex development. This developmental process, together with the complex mating and nesting behavior and the vulnerability of sea turtles to threats of a natural or anthropogenic nature, naturally lead to the study of the population dynamics of the species.?  For this reason, in this paper, we have developed a continuous model given by a system of three ordinary differential equations to study the dynamics of the green sea turtle population long-term, focusing the mathematical simulations on the data obtained for the nesting species of Galapagos Islands. Through the qualitative analysis of the model, the following is demonstrated: 1) The flow induced by the system is positively invariant on the region of biological interest and 2). The given condition on is necessary and sufficient for the unique nontrivial equilibrium point to be globally asymptotically stable in that region. When implementing the estimated values for our parameters in the numerical simulations, it was observed that indeed the population of Galapagos green sea turtles complies with the condition for which the nontrivial critical point is globally asymptotically stable.
Determination of a Strain Energy Density Function for the Tricuspid Valve Leaflets Using Constant Invariant-Based Mechanical Characterizations
Authors: Laurence Devin W. , Lee Chung-Hao
Published: October 2021

The tricuspid valve (TV) regulates the blood flow within the right side of the heart. Despite recent improvements in understanding TV mechanical and microstructural properties, limited attention has been devoted to the development of TV-specific constitutive models. The objective of this work is to use the first-of-its-kind experimental data from constant invariant-based mechanical characterizations to determine a suitable invariant-based strain energy density function (SEDF). Six specimens for each TV leaflet are characterized using constant invariant mechanical testing. The data is then fit with three candidate SEDF forms: (i) a polynomial model—the transversely isotropic version of the Mooney–Rivlin model, (ii) an exponential model, and (iii) a combined polynomial-exponential model. Similar fitting capabilities were found for the exponential and the polynomial forms (R2=0.92–0.99 versus 0.91–0.97) compared to the combined polynomial-exponential SEDF (R2=0.65–0.95). Furthermore, the polynomial form had larger Pearson's correlation coefficients than the exponential form (0.51 versus 0.30), indicating a more well-defined search space. Finally, the exponential and the combined polynomial-exponential forms had notably smaller but more eccentric model parameter's confidence regions than the polynomial form. Further evaluations of invariant decoupling revealed that the decoupling of the invariant terms within the exponential form leads to a less satisfactory performance. From these results, we conclude that the exponential form is better suited for the TV leaflets owing to its superb fitting capabilities and smaller parameter's confidence regions.
A Review on Well Integrity Issues for Underground Hydrogen Storage
Authors: Ugarte Esteban R. , Salehi Saeed
Published: October 2021

Renewable energy production is limited by the fluctuations limiting their application. Underground hydrogen storage (UHS) is one possible alternative to reduce the gap between supply and demand by storing the energy converted to hydrogen as a carrier and store it during surplus to produce it during high demand periods. The hydrogen is stored in the subsurface in geological formations containing the gas and is injected/produced via wells. There is a lack of experience associated with this technology and only a small number of projects worldwide. There are several mechanisms that can compromise the integrity of the well and generate leakage of the stored gas. This paper aims to introduce the challenges associated with well integrity of UHS. Mechanisms that can compromise well integrity and generate leaks include microbial corrosion, hydrogen blistering hydrogen-induced cracking and hydrogen embrittlement, cement degradation, elastomer failure, and caprock sealing failure. Propose well completion criteria, recommendation, and materials selection for newly constructed wells or existing wells. A comparison with more developed storage technologies aims to provide a better understanding of the limitations of hydrogen storage by comparing it to carbon dioxide (carbon capture and storage) and methane (underground gas storage). Finally, evaluation and monitoring techniques are required to see the influence of hydrogen on well integrity. Future research and development will reduce the uncertainties and limitations associated with UHS increasing its feasibility and implementation.
Numerical Assessment of Cavitation Erosion Risk in a Commercial Water-Jet Pump
Authors: Arabnejad Mohammad Hossein , Svennberg Urban , Bensow Rickard E.
Published: October 2021

In this paper, the risk of cavitation erosion is assessed in a commercial water-jet pump using a recently developed numerical erosion assessment method by Arabnejad et al. (2021, “Numerical Assessment of Cavitation Erosion Risk Using Incompressible Simulation of Cavitating Flows,” Wear, 464–465, p. 203529). This assessment is performed for two flow conditions with different cavitation erosion risk according to the experimental paint tests and the high erosion risk areas identified by the method are compared with the experimental results. This comparison shows that the applied method is capable of both identifying the regions of high erosion risk and also capturing the difference between the cavitation erosion risk in the two studied conditions. The latter capability of the numerical assessment method, which has not been reported in the literature for other published methods, is one step forward toward the application of the method in the design process of hydraulic machines. Furthermore, the numerical results are analyzed to explain the reasons for different erosion risk in the two conditions. This analysis reveals that this difference is mostly related to the stronger flow nonuniformities entering the rotor in the most erosive condition. Using the numerical results, one reason behind these stronger nonuniformities is identified to be the stronger bursting of vortices shed from the shaft in the most erosive condition.
Numerical Study of Fully Coupled Fluid-Structure Interaction of Stented Ureter by Varying the Stent Side-Holes
Authors: Martinez Erick , Xu Ben , Li Jianzhi , Yang Yingchen
Published: October 2021

Ureteral stents are a measure used for many medical issues involving urology, such as kidney stones or kidney transplants. The purpose of applying stents is to help relieve the urine flow while the ureter is either blocked or trying to close itself, which creates blockages. These ureteral stents, while necessary, cause pain and discomfort to patients due to them being a solid that moves around inside the patients’ body. The ureter normally moves urine to the bladder through peristaltic forces. Due to the ureter being a hyperelastic material, these peristaltic forces cause the ureter to deform easily, making it necessary for the stent to properly move the urine that flows through it for the patient not to face further medical complications. In this study, we seek to find a relation between the amount of stent side holes and the overall flow rate inside the stent with the ureter contracting due to peristalsis. A fully coupled fluid-structure interaction (FSI) model is developed to visualize how the ureter deforms due to peristalsis and the subsequent effect on the urine flow due to the ureter’s deformation. Numerical simulations using COMSOL Multiphysics, a commercial finite-element based solver, were used to study the fluid-structure interaction, and determine whether the stent performs more properly as the amount of stent side holes increases. The results showed that the stent model with a 10 mm distance between side hole pairs provided the highest outlet flow rate, which indicates a proper stent design that allows for maximized urine discharge. We hope this study can help improve the stent design in kidney transplant procedures to further ease the inconvenience on the patients.
Experimental Study of the Effect of Particle Size on Erosion of Elbows in Series for Annular Gas-Liquid Flows
Authors: Othayq Mazen , Haider Ghulam , Vieira Ronald E. , Shirazi Siamack A.
Published: October 2021

Erosion is a complex process, especially with the presence of small particles and in complex geometries such as elbows in series. Erosion due to the solid particle is affected by different parameters such as material properties, particle material, shape and size, superficial gas and liquid velocities, flow regime and geometry. The main objective of this work is to investigate the effect of particle size in two 3-inch (76.2 mm) diameter elbows in series with curvature radius to pipe diameter ratio (r/D) equal to 1.5. A test section was constructed in a flow loop with a distance between the elbows equal to 12D. Paint removal experiments were conducted to determine the erosion patterns and hot spots of erosion using acrylic elbows. Additionally, erosion experiments were conducted with 300, 75, and 25 μm particle sizes in gas-liquid-sand annular flow in stainless steel elbows. The wall thickness loss of the elbows has been measured using state of the art non-destructive fix-mounted, temperature compensated, ultrasonic transducers. Experimental results showed that higher erosion was obtained with 300 μm particle size where the erosion in the second elbow is lower than the first elbow with the 12D distance. With respect to the maximum erosion ratio of the second elbow to the first elbow, the results showed that the ratio of erosion rates in two elbows (second to first) decreases with increasing the particle size. A higher ratio of the two elbows was obtained with 25 μm compared to 300 and 75 μm particle sizes. However, in the first elbow, the erosion rates decrease with decreasing particle sizes.
Use of Laser Doppler Vibrometry for Measuring Flow-Induced Vibration of a Thermowell in a Pipe Flow
Authors: Chun Sejong , Lee Sibok , Yoon Hyewon
Published: October 2021

Thermowells with helical strakes are becoming promising to prevent them from fatigue fracture by Kármán vortex street. Many studies suggest various kinds of measurement techniques, including strain rate measurement, acceleration measurement, and high-speed visualization to evaluate the role of Kármán vortex street to the flow-induced vibration. Nevertheless, use of laser Doppler vibrometry has not yet been reported in the literature. This study compared the tip deflection of a thermowell due to the flow-induced vibration by using the laser Doppler vibrometry and the strain rate measurement. The laser Doppler vibrometry could measure the tip deflection directly. On the other hand, the strain rate measurement had to convert the strain rate into the tip deflection through the Euler-Bernoulli beam theory. Measurement equivalence between the laser Doppler vibrometry and the strain rate measurement was discussed with the results of tip deflections of the thermowell.
Experimental Investigation of Lagrangian Coherent Structures and Lobe Dynamics in Perturbed Rayleigh-Benard Convection
Authors: Watanabe Masahito , Yoshimura Hiroaki
Published: October 2021

It is well known that Rayleigh-Benard convection with perturbations yields Lagrangian chaotic transport, and the mechanism of inducing chaotic transport has been numerically clarified by lobe dynamics [2]. On the other hand, the mechanism of such Lagrangian transport has not been enough studied by experiments. In our previous work [16], we made an experimental study to investigate the Lagrangian transport appeared in the two-dimensional Rayleigh-Benard convection by giving oscillation on the velocity fields and showed that there exist Lagrangian Coherent Structures (LCSs) which correspond to invariant manifolds of non-autonomous systems. We also showed that the LCSs entangle with each other around cell boundaries. In this paper, we further explore the global invariant structures of the perturbed Rayleigh-Benard convection by clarifying the details on the LCSs and explain how the fluid transport obeys lobe dynamics. Finally, we propose a novel Hamiltonian model for the two-dimensional perturbed Rayleigh-Benard convection that enables to elucidate the global structures detected by experiments.
CFD Modeling of Blood Flow in a Bidirectional Glenn Shunt and a Combined Bidirectional Glenn and Blalock-Taussig Shunt
Authors: Wang Chunhui , Agarwal Ramesh K.
Published: October 2021

Cyanosis or “Blue Baby Syndrome,” is an infant disorder which affects the newly born babies whose skins turn blue or purple because of lack of required blood flow between heart and lung due to pulmonary vascular blockage. Many patients may also have stenosis in vessels. If there is not enough blood flow from heart to the lung, lack of oxygen will cause platelet aggregation and coagulation resulting in elevated wall shear stress which may potentially result in death. In order to address the congenital defect and increase blood flow and oxygen saturation levels within the blood pumping system, a biological shunt is usually planted between innominate veins and left and right pulmonary arteries. The well-known examples are Blalock-Taussig shunt (BT shunt) between right ventricle and pulmonary artery and bidirectional Glenn shunt (BGS) between innominate veins and pulmonary arteries.

The goal of this paper is to study the hemodynamics of BGS, wherein the blood flow goes through superior vena cava (SVC), innominate and subclavian veins and pulmonary arteries. In another simulation, Blalok-Taussing shunt (BTS) is also included along with the BGS. In BTS, the blood directly flows between innominate and pulmonary artery. The models are created with SolidWorks and Blender software based on real patient aorta model parameters. The commercial CFD software ANSYS is used to simulate the blood flow. CFD simulations are performed for blood flow (1) in patient specific aorta model without BGS and (2) in patient specific model with both BGS and BTS. The results for distribution of pressure, velocity and wall shear stress are obtained and analyzed to evaluate the performance of BGS alone and with both BGS and BTS. The computations are compared with limited available clinical data. This study demonstrates how CFD can be effectively utilized in the design of medical devices such as BGS and BTS and to improve the clinical outcomes in patients.
Tracings of Interaction Between Myoblasts Under Shear Flow in Vitro
Authors: Hashimoto Shigehiro , Yokomizo Takashi
Published: October 2021

How does the group of cells make orientation perpendicular to the flow direction? How does contact with an adjacent cell affect the orientation of the cell? The orientation of a cell according to the neighbor cell under shear flow fields has been traced in vitro. A Couette type flow device with parallel discs was manufactured for the cell culture under the controlled constant wall shear stress. Cells (C2C12: mouse myoblast cell line) were cultured on the lower disc while applying the shear flow in the medium by the upper rotating disc. After culture for 24 hours without flow for adhesion of cells, 2 Pa of the constant wall shear stress was continuously applied in the incubator for 7 days. The behavior of each cell was traced by time-lapse images observed by an inverted phase contrast microscope placed in an incubator. The experiment shows the following results quantitatively by parameters: the contact ratio, and the angle between major axes of cells approximated to ellipsoids. As the ratio of the contact length with the adjacent cell to the pericellular length increases in the two-dimensional projection images, the adjacent cells tend to be oriented in parallel with each other.
Design and Investigation on a Centrifugal Compressor for PEM Fuel Cell System
Authors: Zong Bihuan , Zhuge Weilin , Ying Qiyu , Chen Haoxiang , Zhang Yangjun
Published: October 2021

Proton Exchange Membrane Fuel Cell (PEMFC) is a very attractive power source to meet high efficiency and low emission. For mobility applications, PEMFC needs to have a larger power density and it can be achieved with an air compressor to intake more air for chemical reaction. Different from a turbocharger, the compressor for PEMFC is not driven by a turbine, but by an electric motor as well. Due the limitation of motor speed and compact system size, the air compressor must be in small size and operate with low rotational speed. In compressor aerodynamic study, low specific speed and small size is believed to have large loss and it needs to be further investigated and improved. In this paper, a centrifugal compressor combined with an air bearing is specially developed, with rotational speed as 120k RPM and pressure ratio as 3.5. The compressor impeller, diffuser and volute are designed by mean-line method followed by 3D detailed design. Computational fluid dynamics method is employed to predict compressor performance as well as analyze compressor internal flow field and loss mechanism. Simulation results indicate that major losses including leakage flow loss in impeller and loss in diffuser. As a result, corresponding optimization design method is proposed, the total-to-total aerodynamic efficiency of the redesigned compressor has increased 5% at design point.
Influence of Wall Proximity on the Wake Dynamics Behind a Square Cylinder
Authors: Addai Samuel , Mante Afua A. , Kumahor Sedem , Fang Xingjun , Tachie Mark F.
Published: October 2021

In the present study, the effects of wall proximity on the wake dynamics behind a square cylinder subjected to a thick upstream turbulent boundary layer were experimentally investigated using particle image velocimetry. The Reynolds number based on the free-stream velocity and the cylinder height (h) was 12750 while the ratio of the turbulent boundary layer thickness to the cylinder height was 3.6. The gap distance (G) between the bottom face of the cylinder and the wall was varied, resulting in gap ratios (G/h) of 0, 0.3, 0.5, 1.0, 2.0 and 8.0. The flow topological differences among the various gap ratios were analyzed in terms of the mean flow and Reynolds stresses. The results show that as the cylinder approaches the wall, the mean flow becomes increasingly asymmetric about the horizontal centerline of the cylinder and the size of the mean separation bubbles in the cylinder wake increases. Also, the magnitudes of the Reynolds stresses decrease with decreasing gap ratio. For G/h > 0, the distributions of the streamwise Reynolds normal stress and Reynolds shear stress are concentrated along the upper and lower separated shear layers, resulting in characteristic double peaks. The distributions of the vertical Reynolds normal stress, however, are concentrated in the wake about the horizontal centerline of the cylinder and reveal only single peaks.
Numerical Simulation of Wind Effect Over Industrial Chimneys in Cet West Bucharest
Authors: Radulescu Victorita
Published: October 2021

The distribution of wind speed in the Atmospheric Boundary Layer - ABL has an essential role in the structural design and modeling of chimneys in thermal power plants. As a case study, the recently rehabilitated West Thermal Power Plant in Bucharest was selected. For the numerical modeling of the wind effect, a database was developed with the atmospheric parameters monitored for more than two years, in the selected area. The known pressure coefficients - Cp for a chimney are only valid for some conventional forms. In the present paper for the numerical modeling of the Cp coefficient and of the wind velocity coefficient, the real surface of the chimney was analyzed, considering also its roughness. A significant effect of the pressure distribution, known as the suction effect, was observed. The vertical distribution of the horizontal component of wind speed is strongly influenced by the presence of nearby buildings. They act as a roughness effect by producing air turbulence, separating the flow and inducing the “wake effect”. This phenomenon produces a variation of the average parameters of wind speed and turbulence, depending on the height and distribution of the buildings. For a proper modeling, some details are mentioned regarding the characteristics and dimensions of the analyzed chimney, associated with the land surface and its topography, with the wind speed and the structure of the chimney. Next, some criteria for modeling and selecting the geometric scale are mentioned, followed by some details on the meshing solution for the CFD modeling. A fine mesh is preferred for the inner and outer surface of the chimney in the bottom area, around the chimney, with a quality of about 0.75 for each model tested. The quality of the element is determined with a determinant of the Jacobian matrix, as a measure of the distortion of the shape of the elements. The inlet profile of dissipation rate ε produced by the turbulence was considered from the approximation of Richards and Hoxey. Knowing the wind velocity distribution and the coefficient of force exerted on the chimney, the acting force of the wind is determined. Some results obtained by numerical modeling are mentioned in the last part of the paper on wind velocity distribution, pressure values and force distribution, as altitude functions. The obtained results are in agreement with the experimental data, the highest difference being of approximately 3.43 %, in the top of the chimney, depending on the margin of the discretization field.