bluuebunny/crossref_metadata_2025 huggingface dataset:
The theoretical and practical arguments against the unilateral withdrawal of life‐sustaining treatment during crisis standards of care: Does the Knobe effect apply to unilateral withdrawal?
Authors: Maldonado Fabien , Gill Michael B.
Published: September 2022

Some argue that it is ethically justifiable to unilaterally withdraw life‐sustaining treatment during crisis standards of care without the patient's consent in order to reallocate it to another patient with a better chance of survival. This justification has been supported by two lines of argument: the equivalence thesis and the rule of the double effect. We argue that there are theoretical issues with the first and practical ones with the second, as supported by an experiment aimed at exploring whether the Knobe effect, which affects the folk concept of intention, applies to situations of unilateral withdrawal. Fifty‐two critical care physicians from one university were asked to ascribe intention in two hypothetical scenarios A and B in which outcomes differ—the patient from whom life‐sustaining treatment is withdrawn dies in scenario A but survives in scenario B—but the intention, to save the other patient regardless of the outcome of the other, is the same. The survey was administered via a web‐based survey and all answers were anonymous. A paired proportion test was used to compare responses to both questions. All 52 surveyed individuals responded in scenario A and 30 (57.7%) ascribed intention when outcomes were unfavorable, whereas 50 responded in scenario B and 8 (16%) ascribed intention when outcomes were favorable, a difference that was statistically significant (p < 0.001). There are theoretical and practical issues with the arguments proposed to justify the unilateral withdrawal of life‐sustaining treatment based on the equivalence thesis and the rule of double effect.
Change-Plane Analysis for Subgroup Detection with a Continuous Treatment
Authors: Jin Peng , Lu Wenbin , Chen Yu , Liu Mengling
Published: September 2022

Detecting and characterizing subgroups with differential effects of a binary treatment has been widely studied and led to improvements in patient outcomes and population risk management. Under the setting of a continuous treatment, however, such investigations remain scarce. We propose a semiparametric change-plane model and consequently a doubly robust test statistic for assessing the existence of two subgroups with differential treatment effects under a continuous treatment. The proposed testing procedure is valid when either the baseline function for the covariate effects or the generalized propensity score function for the continuous treatment is correctly specified. The asymptotic distributions of the test statistic under the null and local alternative hypotheses are established. When the null hypothesis of no subgroup is rejected, the change-plane parameters that define the subgroups can be estimated. This paper provides a unified framework of the change-plane method to handle various types of outcomes, including the exponential family of distributions and time-to-event outcomes. Additional extensions with nonparametric estimation approaches are also provided. We evaluate the performance of our proposed methods through extensive simulation studies under various scenarios. An application to the Health Effects of Arsenic Longitudinal Study with a continuous environmental exposure of arsenic is presented.
Role of T CD4+ cells, macrophages, C‐low threshold mechanoreceptors and spinal Cav3.2 channels in inflammation and related pain‐like symptoms in murine inflammatory models
Authors: Picard Elodie , Kerckhove Nicolas , François Amaury , Boudieu Ludivine , Billard Elisabeth , Carvalho Frédéric Antonio , Bogard Gemma , Gosset Philippe , Bourdier Justine , Aissouni Youssef , Bourinet Emmanuel , Eschalier Alain , Daulhac Laurence , Mallet Christophe
Published: September 2022

Background and Purpose

T‐type calcium channels, mainly the Cav3.2 subtype, are important contributors to the nociceptive signalling pathway. We investigated their involvement in inflammation and related pain‐like symptoms.

Experimental Approach

The involvement of Cav3.2 and T‐type channels was investigated using genetic and pharmacological inhibition to assess mechanical allodynia/hyperalgesia and oedema development in two murine inflammatory pain models. The location of Cav3.2 channels involved in pain‐like symptoms was studied in mice with Cav3.2 knocked out in C‐low threshold mechanoreceptors (C‐LTMR) and the use of ABT‐639, a peripherally restricted T‐type channel inhibitor. The anti‐oedema effect of Cav3.2 channel inhibition was investigated in chimeric mice with immune cells deleted for Cav3.2. Lymphocytes and macrophages from either green fluorescent protein‐targeted Cav3.2 or KO mice were used to determine the expression of Cav3.2 protein and the functional status of the cells.

Key Results

Cav3.2 channels contributed to the development of pain‐like symptoms and oedema in the two murine inflammatory pain models. Our results provided evidence of the involvement of Cav3.2 channels located on C‐LTMRs and spinal cord in inflammatory pain. Cav3.2 channels located in T cells and macrophages contribute to the inflammatory process.

Conclusion and Implications

Cav3.2 channels play crucial roles in inflammation and related pain, implying that targeting of Cav3.2 channels with pharmacological agents could be an attractive and readily evaluable strategy in clinical trials, to relieve chronic inflammatory pain in patients.
Common strategies in empirically supported psychological interventions for alcohol use disorders: A meta‐review
Authors: Nadkarni Abhijit , Massazza Alessandro , Guda Rahul , Fernandes Luanna T. , Garg Ankur , Jolly Mehak , Andersen Lena S. , Bhatia Urvita , Bogdanov Sergiy , Roberts Bayard , Tol Wietse A. , Velleman Richard , Moore Quincy , Fuhr Daniela
Published: September 2022

Issues

Despite the large number of effective psychological interventions for alcohol use disorders (AUD), there is still a lack of clarity concerning the strategies that make these interventions effective.

Approach

The overall goal of this review was to identify, examine and synthesise the information about common strategies from evidence‐based psychological interventions for AUDs by conducting a review of systematic reviews, that is, a meta‐review. We isolated the relevant primary studies from eligible systematic reviews and extracted information about the interventions from these studies to understand the strategies used. Analysis was restricted to narrative summaries.

Key Findings

Thirteen reviews were eligible for inclusion in our meta‐review. Of these, eight demonstrated the effectiveness of a range of psychological interventions—behavioural couples therapy, cognitive behaviour therapy combined with motivational interviewing, brief interventions, contingency management, psychotherapy plus brief interventions, Alcoholics Anonymous and 12‐step treatment programs, family‐therapy or family‐involved treatment, and community reinforcement approach. The most commonly used component strategies in effective interventions for AUDs included assessment, personalised feedback, motivational interviewing, goal setting, setting and review of homework, problem solving skills and relapse prevention/management.

Implications

Evidence about commonly used strategies in evidence‐based psychological interventions for AUDs offer the possibility of creating menu‐driven interventions that can be tailored to respond to individual client needs and preferences in different contexts.
Value premium and macroeconomic variables
Authors: Beccalli Elena , Doninelli Nicola , Orsini Cesare
Published: September 2022

This paper investigates the effect of macroeconomic expectations on the value premium. We introduce a two‐pass estimation procedure to extrapolate the impact of investors' macroexpectations on the firm fundamental value of Rhodes‐Kropf, Robinson, and Viswanathan. We find that the level and slope of the term structure affect valuation, revealing a heavily industry‐dependent effect. The portfolios sorted on metrics orthogonal to macroeconomic variables show a clear association between the misvaluation component of value premium and size risk. By removing the influence of the macroeconomic conditions and size, we separate the portion of the value premium that rewards macroeconomic expectations.
Elevated levels of sCD48 are inversely correlated with markers of disease activity in bullous pemphigoid
Authors: Treco Emma , Huan Eunice , Varzavand Afshin , Fairley Janet A. , Messingham Kelly N.
Published: September 2022

sCD48 is elevated in diseases characterized by IgE and eosinophilia. Thus, serum levels sCD48 were evaluated in relation to clinical characteristics of Bullous pemphigoid (BP) patients. sCD48 levels were determined by ELISA in sera from 26 patients with classic BP and 26 healthy controls. Disease severity scores, differential blood counts, and circulating autoantibody levels were obtained. A correlation analysis was performed to establish relationships between sCD48 and clinical and laboratory markers of disease severity. Overall, circulating levels of sCD48 were significantly elevated in BP patients; however, when stratified based on disease severity, patients with mild–moderate disease had higher levels of sCD48 than those with severe disease. A Spearman's correlation analysis identified an inverse relationship between sCD48 and disease activity, serum BP180 IgE and peripheral eosinophil numbers. Further studies are needed to determine the pathologic relevance of these findings.
Preservice Spanish teachers analyze a nonexemplary lesson: Critical reflection in teacher preparation
Authors: Edstrom Anne
Published: September 2022

The Challenge

Preservice teachers' personal experiences as learners often shape their pedagogical beliefs. (1) How do preservice teachers evaluate a lesson that does not reflect best practices (as described by the World‐Readiness Standards) at the beginning and at the end of a methods course? (2) How do they describe changes in their perceptions?
Oxidative stability and in vitro release behaviour of microencapsulated Antarctic krill oil and fish oil: the effect of lipid class composition
Authors: Fu Jing‐jing , Fu Dong‐wen , Zhang Guang‐yao , Zhang Zhi‐hui , Shao Zhen‐wen , Ma Zhen‐hua , Tang Yue , Zhou Da‐yong , Song Liang
Published: September 2022

Antarctic krill oil (AKO) and fish oil (FO) were microencapsulated by a pilot‐scale spray dryer in this study. The effect of lipid class compositions on the encapsulation properties of the obtained microcapsules was investigated. The particle size distribution of both microcapsules ranged from 29.23 ± 2.20 to 36.79 ± 3.45 μm, and the moisture content and water activity (aw) also indicated that both AKO and FO microcapsules were suitable for long‐term storage. Interestingly, differences in lipid composition affected the microstructure of the microcapsules formed, thereby affecting their oxidative stability and digestive behaviour. Compared with FO microcapsules, the surface microstructure of PLs‐enriched microcapsules (AKO microcapsules) was smoother, endowing it better oxidative stability and higher DHA (72.13 ± 2.32% vs. 63.08 ± 2.98%) and EPA (75.94 ± 1.43% vs. 68.26 ± 2.98%) bioaccessibility. These findings may have important implications for the development of microcapsules formulated with different lipid classes in the food industry.
Analysis of Bisphenol A migration from microwaveable polycarbonate cups into coffee during microwave heating
Authors: Agarwal Aparna , Gandhi Shivika , Tripathi Abhishek Dutt , Iammarino Marco , Homroy Snigdha
Published: September 2022

Polycarbonate (PC) is a polymer containing Bisphenol A (BPA) monomers in its structure. It is frequently used in manufacturing consumer goods such as food storage containers, reusable water bottles, infant feeding bottles, microwave containers and microwaveable cups. Under varying pH and temperature conditions, additives used in the plastic manufacture can leach in trace levels into the food in contact and negatively affect human health over time. Therefore, quantitative determination of BPA in food can be of great significance. The present study analysed the migration of BPA in coffee from different qualities of polycarbonate microwaveable cups under the influence of microwave heating by reversed‐phase ultra‐high‐performance liquid chromatography (UHPLC). The amount of BPA detected in samples ranged from undetected to 391.105 ± 0.05 μg kg−1. Results obtained indicate that BPA migration is minimal in good‐quality polycarbonate cups. Poor‐quality cups are accelerated time‐dependent; increased contact duration between polycarbonate and hot contact medium leads to more significant BPA migration. Furthermore, the BPA leaching process is enhanced during microwave heating due to high temperatures reached in a short time.
Development, characterisation and biodegradability of rice straw lignin based sustainable biopolymeric films
Authors: Dudeja Isha , Mankoo Ramandeep Kaur , Singh Arashdeep , Kaur Jupinder
Published: September 2022

The present study involved valorization of rice straw via production of biopolymeric films loaded with lignin and evaluation of their physical, mechanical, structural, antioxidant, antibacterial and biodegradable properties. Lignin (0.1%, 0.2% and 0.3%) loaded films were prepared by solvent casting method involving successful crosslinking between PVA, citric acid and lignin which was confirmed by ester bond formation at 1710 cm−1 in Fourier transform infrared spectrum. Scanning electron micrographs showed smooth surface in control and wavy surface in lignin film with no cracks. Lignin films possessed thickness, tensile strength and elongation at break in the range 0.127–0.142 mm, 22–31.38 MPa and 11.83–17.63%, respectively. Lightness value of films decreased while yellowness index increased as the level of lignin increased in films. Lignin loaded films showed potential antioxidant activity (51.4–74.6%) and antibacterial efficacy against Pseudomonas (diameter of inhibition zone 4.1 cm), thus suggesting their role in prevention of bacterial food contamination and organoleptic changes in food. The biodegradability tests showed that weight loss experienced by films after burial in soil was above 78.7% which offers a great advantage of these biopolymeric films over non‐biodegradable synthetic plastics, hence, these may be explored further as bioplastics to replace plastic wraps in food packaging.
Black rice flour‐induced changes in gluten conformation in fresh, pre‐fermented and frozen dough
Authors: Feng Wenjuan , Ma Sen , Sun Binghua , Wang Xiaoxi , Wang Fengcheng
Published: September 2022

Black rice flour greatly enriches the nutrition of flour products, and also alleviates the quality deterioration of frozen dough to a certain extent, but the gluten‐influenced mechanism remains unclear. The effects of black rice flour with different particle sizes on protein molecular weight distribution, secondary structure, fluorescence characteristics, thermogravimetric properties, and chemical interaction of the fresh dough (FD), pre‐fermented dough (PD), and thawed dough (TD) were investigated. The addition of black rice flour resulted in the breaking of disulfide bonds in the FD and an increase in the content of total SDS‐extractable protein. However, the depolymerization of large glutenin polymers in the PD and TD of the composite flour system was lower than wheat flour system, especially in the dough with small particle size black rice flour. As the particle size of black rice flour decreased, the intermolecular force of the composite flour dough system is more prominent, of which the hydrophobic interaction force contributes the most considerable value. In addition, TD in the composite flour system has less weight loss than that of wheat flour system. Therefore, adding black rice flour reduced the deterioration of gluten protein, and the small particle size of black rice flour showed advantages.
Digital skills critical for education: Video analysis of students' technology use in Norwegian secondary English classrooms
Authors: Kure Astrid Elisabeth , Brevik Lisbeth M. , Blikstad‐Balas Marte
Published: September 2022

Background

Globally, digital skills are a crucial aspect of education that schools should develop systematically. Research on digital skills tends to be measured using self‐reports, performance tests or interventions. There is less knowledge about student and teacher uptake of technology in school, making it important to investigate the actual use of technology and digital skills in authentic classroom settings.

Objectives

This study contributes unique baseline data concerning students' use of technology and digital skills across mandatory English courses in real classroom settings in secondary schools in Norway over time.

Methods

The study adapted a national framework for digital skills into an observation protocol. With it, this study analysed videos from 60 naturally occurring English lessons in 13 English classes at seven lower secondary schools over two school years (grades 9 and 10), following 186 students (aged 13–15) and 10 teachers.

Results and Conclusions

Students used digital skills critical for education in half of the video‐recorded English lessons, with more digital skill use at some schools over time. The main finding across classrooms and school years regards students' use of basic, not advanced, digital skills.

Takeaways

Although teachers provide opportunities for students to use digital skills in school, more advanced skills are needed. This work calls for continued use of video recordings to provide systematic comparisons of potential shifts in students' digital skills in real English secondary classroom settings over time.
Biomimetic hydroxyapatite paste for molar–incisor hypomineralization: A randomized clinical trial
Authors: Butera Andrea , Pascadopoli Maurizio , Pellegrini Matteo , Trapani Benedetto , Gallo Simone , Radu Monica , Scribante Andrea
Published: September 2022

Objectives

The aim of this randomized clinical trial was to evaluate the desensitizing and remineralizing effect of a new zinc‐hydroxyapatite‐based paste in sites affected by molar–incisor hypomineralization (MIH), by assessing dental sensitivity, tooth wear, and periodontal indexes.

Materials and Methods

Twenty‐five patients with presence of 1 enamel demineralization of permanent molars and incisors in two different quadrants were recruited. After professional dental hygiene, a domiciliary hydroxyapatite‐based paste was assigned and recommended to be applied on 2 MIH teeth in one random quadrant (test group), while the 2 contralateral MIH teeth did not undergo paste application (control group). The following primary outcomes were assessed: Plaque Control Record (PCR), Bleeding Index (BI), MIH Treatment Need Index (MIH‐TNI), and Schiff Air Index (SAI).

Results

No significant inter‐ and intragroup differences were found for PI and BI, except for both intragroup T0–T1. For MIH‐TNI, significant intergroup differences were detectable in the test group after 9 months of treatment. For SAI values, no significant differences were found in the control group, while in the test group, significant lower values were found after 1 and 3 months since baseline, respectively.

Conclusions and Clinical Relevance

Biomimetic zinc‐hydroxyapatite showed a desensitizing effect when used to treat MIH.
Hormone‐response transcriptional landscapes of wheat seedlings and the development of a JA fluorescent reporter
Authors: Li Xiao‐Ming , Wang Chu‐Yang , Guo Yue‐Ting , Guo Yu‐Xin , Du Han‐Xiao , Niu Ke‐Xin , Yan Yan , Gou (缑金营) Jin‐Ying
Published: September 2022

Wheat is an essential energy and protein source for humans. Climate change brings daunting challenges to wheat yield through environmental stresses, in which phytohormones play critical roles. Nevertheless, the comprehensive understanding of wheat phytohormone responses remains elusive. Here, we investigated the transcriptome response of wheat seedlings to five phytohormones, cytokinin (6‐BA), abscisic acid (ABA), gibberellic acid (GA), jasmonate (JA) and salicylic acid (SA). We further selected two JA marker genes and cloned their promoters to drive the expression of 3XEGFP (tandem trimeric enhanced green fluorescent protein) in transgenic lines. The JA fluorescent reporter displayed a fast and stable response to JA treatment as an ideal tool to follow JA dynamics during fungal and cold stresses at a cellular resolution. Overall, this study provided a transcriptional landscape and facilitated generating fluorescent reporters to monitor the dynamics of phytohormones in food crops.
Developmental disorders in school children are related to allergic diseases
Authors: Zaitsu Masafumi , Mizoguchi Tatsuhiro , Morita Shun , Kawasaki Shohei , Iwanaga Akira , Matsuo Muneaki
Published: September 2022

Background

In children, relationships between developmental disorders such as attention‐deficit hyperactivity disorder (ADHD) and autism spectrum disorder and allergic diseases remain controversial, because these diseases show age‐ and sex‐related differences. A proper understanding of the relationships between developmental disorders and allergic diseases should improve medical care for both diseases. We confirmed the prevalence of allergic diseases in elementary school‐age children with developmental disorders by grade and sex.

Methods

The subjects were 446 lower grade and 312 upper grade elementary school‐age children who had visited our hospital. The prevalence of allergic diseases among subjects with and without developmental disorders by grade and sex was examined using the diagnostic names on medical records.

Results

The prevalence of allergic diseases was significantly higher in lower grade boys and girls with developmental disorders than in those without developmental disorders (boys: OR 3.22, 95%; CI 1.49–6.95; girls: OR: 3.87, 95% CI: 1.27–11.82). The prevalence of allergic diseases was significantly higher in higher grade boys with developmental disorders than in those without developmental disorders (OR: 3.46, 95% CI: 1.59–7.53). Multiple logistic regression analysis in lower grades revealed that ADHD correlated with bronchial asthma (adjusted OR: 3.72, 95% CI: 1.42–9.69) and that autism spectrum disorder correlated with atopic dermatitis (adjusted OR: 4.26, 95% CI: 1.36–13.36). Analyses of children in the upper grades showed that ADHD correlated with atopic dermatitis (adjusted OR: 5.06, 95% CI: 1.28–20.05).

Conclusions

Elementary school‐age children with developmental disorders were more likely to have allergic diseases. The types of allergic diseases related to developmental disorders differed by grade and sex.
Model of severe malaria in young mice suggests unique response of CD4 T cells
Authors: Smith Margaret R. , Gbedande Komi , Johnson Corey M. , Campbell Logan A. , Onjiko Robert S. , Domingo Nadia D. , Opata Michael M.
Published: September 2022

Severe malaria occurs most in young children but is poorly understood due to the absence of a developmentally‐equivalent rodent model to study the pathogenesis of the disease. Though functional and quantitative deficiencies in innate response and a biased T helper 1 (Th1) response are reported in newborn pups, there is little information available about this intermediate stage of the adaptive immune system in murine neonates. To fill this gap in knowledge, we have developed a mouse model of severe malaria in young mice using 15‐day old mice (pups) infected with Plasmodium chabaudi. We observe similar parasite growth pattern in pups and adults, with a 60% mortality and a decrease in the growth rate of the surviving young mice. Using a battery of behavioral assays, we observed neurological symptoms in pups that do not occur in infected wildtype adults. CD4+ T cells were activated and differentiated to an effector T cell (Teff) phenotype in both adult and pups. However, there were relatively fewer and less terminally differentiated pup CD4+ Teff than adult Teff. Interestingly, despite less activation, the pup Teff expressed higher T‐bet than adults' cells. These data suggest that Th1 cells are functional in pups during Plasmodium infection but develop slowly.
The ill winds of COVID‐19: How the pandemic improved respiratory health for some
Authors: Hancox Robert J. , Chang Catherina L.
Published: September 2022

See related article
Black Immigrant Children: Abjection, In(ex)clusion and School Mathematics Reform
Authors: Valoyes-Chavez Luz , Andrade-Molina Melissa Valeska
Published: September 2022

This paper examines the limits and possibilities of the discourses and practices of inclusion of Black immigrant students in reform mathematics classrooms. Data from a larger qualitative study concerned with the education of mathematics teachers in Chilean marginalized schools is used. Conceptualizations about the dynamics of exclusion and inclusion help us illustrate how reform mathematics teaching entails double gestures of hope (about “us”) and fear (about the “others”). The results provide evidence that educational reforms and policies are embedded in a system of reason which historically fabricated Blacks as invisible and inferior, shaping the chances of inclusion of Black children.
A Mechanistic Model for the Predictive Maintenance of Heavy-Duty Centrifugal Fans Operating With Dust-Laden Flows
Authors: Vulpio Alessandro , Oliani Stefano , Suman Alessio , Zanini Nicola , Saccenti Paolo
Published: September 2022

Heavy-duty centrifugal fans are employed for the transport of dust-laden flows in industrial plants, for cement or steel production, or in energy production of plants and mine ventilation systems. These applications require the disposal of huge amounts of suspended particles, which can lead to a gradual erosion of the machine parts where impacts take place. The wear of the fan components can lead to premature failure of the machine, threatening human safety and reliability of the whole plant. The assessment of the wear severity of the machine, according to the process parameters, can aid the plant owner in scheduling overhaul operations along with the operative life of the machine. Moreover, through a reliable estimation of the wear severity, fan manufacturers can optimize the whole machine design process, from the material selection to the warranty time assessment. This work aims to develop a semi-empirical method capable of estimating the erosion severity of centrifugal fans employed for heavy-duty operations. A mechanistic model which accounts for the erosion on the blade leading edge is proposed. The model is derived by means of an analytical approach and accounts for a number of operating parameters (i.e.,, fan geometry, fan operating point, particle concentration in the flow, fluid properties, and material erosion resistance). A comparison of the theoretical model to the computational fluid dynamic (CFD) simulation results obtained through the use of multiphase particle tracking is also provided to assess the reliability of the present method.
Influence of Elevated Fuel Temperatures on the Spray Characteristics of Gasoline—Ethanol Blends
Authors: Miganakallu Niranjan , Purushothaman Ashwin Karthik , Atkinson William R. , Peters Nathan , Amaral Tadeu Miguel Malago , Leite Antonio Galdino , Yoshino Fernando Jun , Bunce Michael , Ra Youngchul , Naber Jeffrey D.
Published: September 2022

In this study, the effect of elevated fuel temperatures on the spray characteristics of gasoline—ethanol blends was studied in an optically accessible constant volume spray and combustion vessel. MAHLE SmartHeat® is a fuel heater located directly upstream of the fuel injector. High speed images of the spray injected from a six-hole gasoline direct injection injector typical of a side-injection engine were captured with shadowgraph imaging technique. Two fuel blends, gasoline with 10% ethanol (E10) and 85% ethanol (E85) were investigated at ambient conditions of 1 bar, 45 °C and 4 bar, 180 °C at an injection pressure of 100 bar. Fuel temperatures were varied from 75 to 250 °C. A comparison of the near nozzle and the global spray characteristics was made for the two fuels in the range of fuel temperatures selected. Results showed that flash boiling leads to two primary effects for the two fuel blends: (i) an appreciable increase in spray angle near the exit of the nozzle followed by (ii) a decrease in spray angle downstream of the nozzle due to the interaction of the plumes and the collapsing of the spray. Furthermore, for both fuel blends, upon flash boiling, entrainment and mixing were reduced downstream of the nozzle because of the collapse of the spray. To reduce this effect, nozzle orientations and geometries should be modified.
A Model and Experimental Validation for a Piston Rings—Squeeze Film Damper: A Step Toward Quantifying Air Ingestion
Authors: Koo Bonjin , San Andrés Luis
Published: September 2022

Rotor-bearing systems often rely on squeeze film dampers (SFDs) to increase the dynamic stability and reduce rotor motion amplitudes while traversing critical speeds. In aircraft engines, to increase the damping capacity within a limited physical space, piston rings (PRs) seal the axial ends of a squeeze film land. However, lubricant still leaks through the slit in the PR abutted ends, and air enters into the film to make a bubbly oil mixture with a much reduced damping capability. This paper presents a volume of fluid (VOF) model for a PR sealed ends SFD facing ambient air (not submerged in lubricant and prone to air entrainment) and delivers predictions benchmarked against experimental results obtained in a dedicated test rig. A lubricant feeds pressure and flows large enough to prevent air ingestion vary with the damper geometry, the lubricant inlet and outlet conditions, and the kinematics of the journal. A parametric study for a typical SFD shows the period-averaged gas volume fraction (GVF) increases as the journal squeeze film velocity (vs) increases and as the film clearance decreases. Most importantly, the location of the PR slit relative to the feedhole affects the amount of air drawn into the film. When the PR slit faces a feedhole, the film land is mostly filled with a pure lubricant. The GVF increases as the arc distance from the PR slit to the feedhole increases. The physical model, anchored by the test data, effectively addresses a fundamental challenge in SFD design and operation; namely, quantifying the amount of air ingested and its effect on the damper forced performance.
Influence of Geometric Parameters for a 100 kW Inward Flow Radial Supercritical CO2 Turbine
Authors: Hoque Syed J. , Kumar Pramod , Gopi Pramod Chandra
Published: September 2022

Highly compact and efficient design makes inward flow radial (IFR) turbine a preferred choice for kilowatt scale supercritical CO2 (sCO2) power blocks. The influence of geometric design parameters on sCO2 turbine performance differs from gas turbines because of their small size, high rotational speeds, and lower viscous losses. The paper presents a computational fluid dynamics (CFD) study for a 100 kW IFR turbine to arrive at optimal geometric design parameters—axial length, outlet-to-inlet radius ratio, number of rotor blades, and velocity ratio, and understand their influence on the turbine's performance. The results are compared with well-established gas turbine correlations in the specific speed range of 0.2 to 0.8 to understand the implications on sCO2 IFR turbines. The analysis shows significant variations in the optimal values of design parameters when compared with gas turbines. It is found that sCO2 turbines require fewer blades and higher velocity ratios for optimal performance. The maximum turbine efficiency (∼82%) is achieved at a lower specific speed of ∼0.4 compared to a gas turbine with specific speed varying between 0.55 and 0.65. Additionally, higher negative incidence angles in the range of −50 deg to −55 deg are required at high specific speeds to counter the Coriolis effect in the rotor passage. The paper presents the variation of stator, rotor, and exit kinetic energy losses with specific speeds. The cumulative losses are found to be minimum at the specific speed of ∼0.4.
Unit-Based Design of Cross-Flow Heat Exchangers for LPBF Additive Manufacturing
Authors: Liang Xuan , White Lisha , Cagan Jonathan , Rollett Anthony D. , Zhang Yongjie Jessica
Published: September 2022

The structural design and additive manufacturing (AM) of cross-flow heat exchangers (HXs) are studied. A unit-based design framework is proposed to optimize the channel configuration in order to improve the heat exchange performance (HXP) and meanwhile control the pressure drop (PD) between the fluid inlet and outlet. A gradient-based optimization methodology is employed to drive the design process. Both shape and topology changes are observed during the channel configuration evolution. Moreover, AM printability evaluation is considered and some re-design work is proposed to improve the printability of the designs with respect to the metal laser powder bed fusion (LPBF) process. For an optimized structure from the unit-based design, corner rounding operation is adopted first, specifically to avoid sharp features. Then the building process of the entire HX containing top, bottom caps, side walls, and the optimized thin-walled channels is simulated, and residual deformation is predicted through sequential layer-by-layer analysis. Based on the residual deformation profile, geometrical compensation is implemented to reduce geometrical inaccuracy of the printed HX. In addition, build orientation selection is also studied to avoid overhang issues in some specific unit-based design results. Finally, a mature design scheme for the cross-flow HX can be achieved as the solution that leads to largely improved HXP (e.g., nearly 200% increase), well controlled PD, and enhanced printability with respect to the LPBF AM process.
Realization of a Gear-Spring Balancer With Variable Payloads and Its Application to Serial Robots
Authors: Nguyen Vu Linh
Published: September 2022

This paper presents a method for realizing a gear-spring balancer (GSB) that can cope with variable payloads and its application to serial robots. The GSB is constructed with a three-gear train articulating a nonzero-free-length spring to a rotating link with a mass to be statically balanced. In the proposed method, the parameters of the GSB are derived from solving the identity problem of perfect static balancing. The significance of this method is that it enables the GSB to handle variable payloads via energy-free adjustment and allows the selection of spring stiffness. The effectiveness of the proposed method was demonstrated through a numerical example and experimental tests. The analytical results showed that the GSB theoretically achieved perfect static balancing even when the payload varied. The peak actuator torque of the GSB was practically reduced by more than 90% with different payloads. In this work, the application of the GSB to serial robots is described to underline the significance of the payload variability of the GSB in pick-and-place operations. A theoretical model illustrated that the peak actuator torques of a serial robot were reduced by an average of 93.4% during operation.
Sensitivity Analysis and Accuracy Synthesis of a Deployable Antenna Considering Clearances and Link Tolerances
Authors: Ding Jianzhong , Dong Yang , Liu Xueao , Wang Chunjie
Published: September 2022

Antenna panels of a satellite are usually deployed and supported by a deployable mechanism. The accuracy of the deployable mechanism is important because it directly affects the performance of the satellite. This article focuses on the accuracy analysis of a deployable antenna considering the coupled effects of joint clearances and link tolerances, and based on which, two accuracy synthesis methods are further discussed. A novel geometric error modeling method is proposed to estimate the error space of the outer panel of the antenna. The advantages of the proposed method are that it can handle the overconstrained constraints efficiently and decouple the positioning error and orientation error. Moreover, the error space is visualized using a sampling method. Based on the proposed error modeling method, the maximum orientation and positioning errors are computed, and following which, sensitives of the antenna accuracy to tolerances considering various sizes of clearances are analyzed. Finally, two optimization methods for accuracy synthesis are discussed, and instructive conclusions are drawn.
A Multi-Objective Comprehensive Evaluation of Heat Transfer Performance of a Direct-Contact Heat Exchanger
Authors: Li Biao , Yang Puyi , Li Zexi , Xu Jianxin , Wang Hua
Published: September 2022

Direct-contact heat exchangers have great potential for waste-heat utilization. This study established a multi-objective evaluation model of the volumetric heat-transfer coefficient, entransy dissipation, and uniformity of the temperature difference field of the direct-contact heat exchanger. The optimal operating parameters for the heat exchanger were obtained by experimentally investigating the relationship between the operating parameters and the volumetric heat-transfer coefficient, entransy dissipation, and uniformity of the temperature difference field. The results indicated that the smaller the entransy, the greater the effectiveness of the heat exchanger in the direct-contact heat exchanger. The results also indicated that the volumetric heat-transfer coefficient increased with the increase in the flowrate ratio and initial temperature difference. The study found that entransy demonstrated the smallest dissipation and the largest effectiveness of the heat exchanger when the initial temperature difference was 120 °C and the flow ratio was 6:1. This study has guiding significance for the optimal design of direct-contact heat exchangers.
Numerical Investigation on the Cooling Effectiveness and Pressure Loss of a Novel Laminated Cooling Configuration With Cellular Partition
Authors: Li Honglin , Xie Feifan , Wang Yaning , Wang Chen , Yan Yan , Cui Jiahuan
Published: September 2022

The laminated cooling is believed to be a promising cooling scheme for the next generation of advanced gas turbines. In order to build a cooling system with high performance, it is necessary to develop a more revolutionary cooling configuration for hot components in gas turbines. In this study, a novel laminated cooling configuration with cellular partition has been proposed. The local/average heat transfer parameters and pressure loss coefficient have been evaluated by comparing with traditional laminated cooling configurations with and without circular pin. Different adiabatic and conjugate cooling configurations are explored numerically to investigate the external film coverage and internal heat transfer. Seven different flow conditions with blowing ratios ranging from 0.2 to 1.4 are investigated for all numerical models. Results indicate that the novel laminated cooling configuration exhibits a higher cooling advantage. With the blowing ratios investigated, the cooling effectiveness of laminated cooling configuration with cellular partition increased by 4.5–13.4% and 10.8–23.4% compared with the cases with and without circular pin, respectively. With higher cooling performance, the pressure loss coefficient only increased by 4.4%. Two mechanisms have been identified for heat transfer enhancement of the novel laminated cooling configuration: (1) the cellular partition increases the transverse diffusion of film cooling outflow resulting in an increased external film cooling effectiveness and (2) the film hole area and partition area have been increased in the new structure, which enhances the internal heat transfer. The proposed structure has the potential for cooling the high-pressure turbines in the future.
Optimizing and Modelling Performance Parameters of IC Engine Fueled With Palm-Castor Biodiesel and Diesel Blends Combination Using RSM, ANN, MOORA and WASPAS Technique
Authors: Samuel Olusegun D. , Pathapalli Venkateshwar R. , Enweremadu Christopher C.
Published: September 2022

Biodiesel fuel properties and engine characteristics can be improved by using hybrid biodiesel and robust optimization tools. This study predicts the performance parameters of diesel engines fueled with castor-palm kernel biodiesel (CPKB) and diesel fuel blend using response surface methodology (RSM) and artificial neural network (ANN). Optimization of the performance parameters was also carried out using multi-criteria decision-making methods (WASPA S and MOORA) for the first time. The RSM and ANN were employed in predicting the performance parameters such as CPKB fuel blends (FB) (0–20 vol.%), engine load (EL) (0–50%), and engine speed (ES) (1000–2000 rpm) on the performance indicators viz. brake torque (BT), brake power (BP), brake specific fuel consumption (BSFC), brake thermal efficiency (BTE). The Box-Behnken design was used for performing the experimental trials. The RSM model predicted the BT of 107.95 Nm, BP of 11.300 kW, BSFC of 0.057 kg/kWh, BTE of 15.147%, at the optimal level of CPKB blends of 20% (B20), engine load of 50%, and an engine speed of 1000 rpm, respectively. Results showed that based on the values of R2and average absolute deviation (AAD) obtained, the predictive capability of both RSM and ANN were within acceptable limits.

The best experimental trial from the WASPAS method is the #20 experimental run and the parameter combination are FB-10%, EL-25, and ES-1500 rpm, whereas for the MOORA method, five such experimental trials were observed viz., #1 run: FB-0%, EL-0, and ES-1000 rpm, #2 run: FB-20%, EL-0 and ES-1000 rpm, #5 run: FB-0%, EL-0, and ES-2000 rpm, #6 run: FB-20%, EL-0, and ES-2000 rpm #11 run: FB-10%, EL-0, and ES-1500 rpm.
Comparison of Solar Thermal Collectors and Solar PV Heat Pump Systems
Authors: Mitri Frederick B. , Anderson Kevin R.
Published: September 2022

This paper presents a comparison between traditional flat plate solar thermal collector systems and solar photovoltaic (PV) heat pump systems. The purpose of this analysis was to determine whether or not heat pump technology has matured to the point that a solar PV system paired with a heat pump could outperform a traditional solar thermal flat plate collector system. To this end, two systems with identical panel footprints of 7.6 m2 (82 ft2) were modelled and analyzed at four different locations being Los Angeles CA, Phoenix AZ, Seattle WA, and Denver CO. The expected energy production and Levelized Cost of Energy (LCOE) for both systems at these locations were determined. The solar fraction for the solar thermal collector systems and PV heat pump systems at the four locations studied were found to be f = 0.44 and f = 0.99 in Los Angeles, f = 0.44 and f = 1.00 in Phoenix, f = 0.21 and f = 0.62 in Seattle, and f = 0.34 and f = 0.90 in Denver. As such, it is evident that the solar PV heat pump systems produced more thermal energy than the solar thermal collectors at all locations tested. The LCOE for the solar thermal collector systems and solar PV heat pump systems at each location were found to be 48.42 ¢/kWh and 36.57 ¢/kWh at Los Angeles, 55.37 ¢/kWh and 36.13 ¢/kWh at Phoenix, 81.47 ¢/kWh and 97.29 ¢/kWh at Seattle, and 52.27 ¢/kWh and 67.50 ¢/kWh at Denver. From these values, it can be seen that the solar PV heat pump systems have a lower LCOE in the warmer climates where ground source heat pumps are not needed but have slightly higher LCOE values in cooler climates where they are. As such, this study has found that solar PV heat pump systems have matured enough to outperform solar thermal flat plate collectors in most situations.
A Non-Intrusive Particle Temperature Measurement Methodology Using Thermogram and Visible-Light Image Sets
Authors: Ortega Jesus D. , Anaya Guillermo , Ho Clifford K. , Vorobieff Peter , Mohan Gowtham
Published: September 2022

The direct measurement of the particle egress rate and heat losses from a particle receiver has been a topic of interest for the advancement of CSP technologies. Particle-plumes that egress from the receiver’s cavity have variable size, density, and rate of egress, which can be a challenge for the field of thermometry. In a previous publication, a methodology to estimate the average particle temperature and discharge rate of a particle curtain was developed by the University of New Mexico (UNM)-Sandia team. This work focuses on the application of a novel non-intrusive method using a high-speed IR camera (ImageI8300 from Infratec) and a visible-light camera (Nikon D3500) to achieve the estimation of the particle egress rate as well as the corresponding advective losses of the particle-plume during on-sun tests at Sandia. Data sets were collected for multiple test days with different test conditions throughout the test campaign. To understand which variables impact the particle egress rate of the receiver, a correlation analysis was completed to determine the impact of 6 variables which include: average particle temperature, curtain mass flow rate, input heat flux, wind speed and direction, and receiver flow configuration. From the results, it was determined that the average particle temperature as well wind direction have a positive correlation to increased particle losses from the system.
Study of the Piezoelectric Properties of UV-Selective Optically Transparent Zn(O,S) Based Solar Cells
Authors: Hijazi Iyad , Xie Rui
Published: September 2022

Hybrid photovoltaic and piezoelectric structures can convert photons to electrical energy by using the photovoltaic part and mechanical energy to electrical energy by using the piezoelectric part, in the presence of rain, wind etc, where there is not enough sunlight for photo-conversion. To date, state-of-the art UV-selective solar cells are mainly based on the use of zinc oxide (ZnO) as the absorber material. ZnO presents high absorption coefficient (α(λ) > 104 cm−1 for λ < 390 nm) and a direct energy bandgap of 3.37 e V. By anion alloying ZnO with sulfur (S), it is possible to fabricate Zn(O,S) mixed crystals that present a bandgap energy bowing with a reported minimum value at 2.7 eV, presenting a more optimal spectral match with the UV region. These structures can be used to create UV-selective solar cells with high transparency in the visible region, that can be utilized in many applications including the development of nonintrusive building-integrated photo-voltaic (BIPV) elements as transparent solar windows and glass-based solar façades. In addition, ZnO and Zinc Sulfide (ZnS) have the ability to convert applied mechanical strain energy to harvestable electrical energy in nano/microdevice. The wurtzite ZnO and ZnS materials exhibit excellent piezoelectric property along the [0001] direction because of their non-centrosymmetric structure. Therefore, in this research we conducted molecular dynamic (MD) simulations on a selected UV-TPV Zn(O1–xSx) structures and reported their polarization and the piezoelectric constants and compared them to pure ZnO and ZnS structures.

The MD results show that the polarization and piezoelectric constants values were all intermediate between those obtained for ZnO and ZnS bulk structures, indicating good piezoelectric properties for the Zn(O1–xSx) structures.