bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance gradient distribution of (Ti,W)C cermet by skin effects of high‐frequency spark plasma sintering
Authors: Yi Mingdong , Wang Zhiyong , Song Yingjie , Meng Zheng , Chen Zhaoqiang , Xiao Guangchun , Xu Chonghai
Published: September 2022

A (Ti,W)C cermet with graded properties was prepared using high‐frequency spark plasma sintering (HF‐SPS). The effects of the sintering process on the microstructure and mechanical properties of the prepared cermet material were studied, and the densification behavior of the material was analyzed using scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Owing to the skin effect and pulse current discharge in HF‐SPS, the experimental results showed different sintering effects, as indicated by the current density difference between the surface layer and bulk. On one hand, the surface‐layer grains were larger, the metal phase was concentrated, and the hardness was high; however, the bulk grains were smaller, the metal phase was uniformly distributed, and the strength and toughness were high, causing the material to account for the higher hardness of the surface layer and the bulk strength and toughness. The skin effect of pulse direct current was key for the performance gradient distribution, whereas increases in the current density and sintering temperature decreased the skin effect. In general, the Joule heat effect was more significant, leading to abnormal grain growth.
Disentangling empowerment: Considering the role of employee perceptions in adaptive selling
Authors: Rigolizzo Michele , Johnson Kevin J. , Harvey Jean‐François
Published: September 2022

As more jobs require employees to continually learn and adapt, empowering employees to adopt learning goals becomes a competitive advantage. Although research has identified key leadership behaviors that empower employees, the relationship between managers and empowered employees is ongoing and dynamic. Therefore, it is important to understand how key leadership behaviors interact with employees in their current state of empowerment to influence learning and performance. In this paper, we draw from self‐determination theory to argue that the way employees perceive a given leadership behavior will differ by dimension of empowerment, and these perceptions impact their intrinsic motivation to learn. Specifically, employees who are high in competence and impact will perceive the leadership behavior of goal clarity as controlling, and be less likely to set learning goals, while those who are high in autonomy and meaning will perceive the same behavior as supportive, and be more likely to set learning goals. In a time‐lagged study of 349 salespeople, we find that goal clarity acts as a boundary condition by weakening the relationship between empowerment and learning goal orientation (LGO) for those high on the competence and impact dimensions. As hypothesized, we find that the same behavior of goal clarity actually strengthens the relationship for those high on the autonomy and meaning dimensions. Further, we provide theoretical and empirical evidence that LGO mediates the relationship between empowerment and adaptive selling.
Gross anatomical description of the extrinsic and intrinsic scapular and brachial muscles of Sapajus apella (Linnaeus, 1758)
Authors: Monroy‐Cendales María José , Vélez‐García Juan Fernando , Castañeda‐Serrano Román David , Miglino Maria Angélica
Published: September 2022

Background

The robust brown capuchin monkey (Sapajus apella) is a South American primate with preferences for arboreal locomotion, which requires specific thoracic limb muscle adaptations. The present investigation studied the gross anatomy of the extrinsic and intrinsic scapular and brachial muscles.

Methods

Gross dissections were performed in both thoracic limbs of four formaldehyde‐fixed specimens.

Results

Three rhomboideus muscles were present (capitis, cervicis, and thoracis). The trapezius muscle was divided into two parts (cervicis and thoracis). The pectoralis abdominalis and omotransversarius muscles were present. The anconeus muscle was found as an individual muscle or fused to the caput mediale of the triceps brachii muscle. The brachialis muscle had among one and two heads. The anconeus epitrochlearis was absent.

Conclusion

These muscles of Sapajus apella are adapted for arboreal locomotion and some terrestrial habits, since these have many similarities with other primates with a similar locomotor patterns.
CCN6improves hepatic steatosis, inflammation, and fibrosis in non‐alcoholic steatohepatitis
Authors: Song Yiran , Li Chenyang , Luo Yuxin , Guo Jinbo , Kang Yaxing , Yin Fengrong , Ye Lihong , Sun Donglei , Yu Jun , Zhang Xiaolan
Published: September 2022

Background and Aims

CCN6 is a secretory protein with functions of maintaining mitochondrial homeostasis and anti‐oxidative stress; and yet, whether it is involved in the pathogenesis of non‐alcoholic steatohepatitis (NASH) is still obscure. We investigated the role and mechanism of CCN6 in the development of NASH.

Methods

Human liver tissue samples were collected to detect the expression profile of CCN6. High‐fat‐high‐cholesterol (HFHC) and methionine choline‐deficient (MCD) diet were applied to mice to establish NASH animal models. Liver‐specific overexpression of CCN6 was induced in mice by tail vein injection of adeno‐associated virus (AAV), and then the effect of CCN6 on the course of NASH was observed. Free fatty acid (FFA) was applied to HepG2 cells to construct the cell model of steatosis, and the effect of CCN6 was investigated by knocking down the expression of CCN6 through small interfering RNA (siRNA) transfection.

Results

We found that CCN6 expression was significantly downregulated in the liver of NASH. We confirmed that liver‐specific overexpression of CCN6 significantly attenuated hepatic steatosis, inflammation response and fibrosis in NASH mice. Based on RNA‐seq analysis, we revealed that CCN6 significantly affected the MAPK pathway. Then, by interfering with apoptosis signal‐regulating kinase 1 (ASK1), we identified the ASK1/MAPK pathway pairs as the targets of CCN6 action.

Conclusions

CCN6 protects against hepatic steatosis, inflammation response and fibrosis by inhibiting the activation of ASK1 along with its downstream MAPK signalling. CCN6 may be a potential therapeutic target for the treatment of NASH.
Discordant population structure among rhizobium divided genomes and their legume hosts
Authors: Riley Alex B. , Grillo Michael A. , Epstein Brendan , Tiffin Peter , Heath Katy D.
Published: September 2022

Symbiosis often occurs between partners with distinct life history characteristics and dispersal mechanisms. Many bacterial symbionts have genomes comprising multiple replicons with distinct rates of evolution and horizontal transmission. Such differences might drive differences in population structure between hosts and symbionts and among the elements of the divided genomes of bacterial symbionts. These differences might, in turn, shape the evolution of symbiotic interactions and bacterial evolution. Here we use whole genome resequencing of a hierarchically structured sample of 191 strains of Sinorhizobium meliloti collected from 21 locations in southern Europe to characterize population structures of this bacterial symbiont, which forms a root nodule symbiosis with the host plant Medicago truncatula. S. meliloti genomes showed high local (within‐site) variation and little isolation by distance. This was particularly true for the two symbiosis elements, pSymA and pSymB, which have population structures that are similar to each other, but distinct from both the bacterial chromosome and the host plant. Given limited recombination on the chromosome, compared to the symbiosis elements, distinct population structures may result from differences in effective gene flow. Alternatively, positive or purifying selection, with little recombination, may explain distinct geographical patterns at the chromosome. Discordant population structure between hosts and symbionts indicates that geographically and genetically distinct host populations in different parts of the range might interact with genetically similar symbionts, potentially minimizing local specialization.
Temperature dependence of O2 respiration in mangrove leaves and roots: implications for seedling dispersal phenology
Authors: Inoue Tomomi , Akaji Yasuaki , Baba Shigeyuki , Noguchi Ko
Published: September 2022

Seasonal differences in diaspore dispersal of three mangrove species, Kandelia obovata, Bruguiera gymnorrhiza and Rhizophora stylosa, suggest that respiratory energy production and demand may differ as a result of interspecific differences in temperature dependence of growth and maintenance processes during seedling establishment.

We analyzed growth, temperature dependencies of respiratory O2 consumption and amounts of respiratory chain enzymes in seedlings of these species grown at various temperatures.

Respiration rates measured at the low reference temperature, RREF, were highest in leaves of 15°C‐grown K. obovata, whose dispersal occurs in the cold season, while root RREF of 15°C‐grown R. stylosa was 60% those of the other species, possibly because of warm conditions during its establishment phase. In leaves and roots of K. obovata and leaves of R. stylosa, the overall activation energy, Eo, changed with growth temperature associated with changes in the ratios of the amount of protein in the two respiratory pathways. However, Eo of seedlings of B. gymnorrhiza, which has a long dispersal phase, were constant and independent of growth temperature.

The different temperature responses of seedling respiration and growth among these three species may reflect the seasonal temperature range of seedling dispersal and establishment in each species.
Childhood asthma and type 1 diabetes mellitus: A meta‐analysis and bidirectional Mendelian randomization study
Authors: Xie Junyang , Chen Gui , Liang Tianhao , Li Ang , Liu Weixing , Wang Yiyan , Wang Xiaofen , Kuang Xiaoxuan , Han DeMin , Liao Wenjing , Song Lijuan , Zhang Xiaowen
Published: September 2022

Background

Worldwide incidence and prevalence of both asthma and type 1 diabetes mellitus (T1DM) in children have been increasing in past decades. Association between the two diseases has been found in some but not in other studies.

Objective

We conducted a meta‐analysis to verify such an association, and bidirectional Mendelian randomization analysis to examine the potential cause‐effect relationships.

Methods

Three databases (PubMed, Embase, and Web of Science) were searched from their inception to February 1, 2021. Pooled hazard ratios (HR) or odds ratios (OR), and 95% confidence intervals, were calculated. Associations between single‐nucleotide polymorphisms with childhood asthma and T1DM were selected based on genome‐wide association studies. The outcome datasets were obtained from FinnGen study. We used the inverse‐variance‐weighted (IVW), weighted median and MR‐Egger methods to estimate causal effects. To assess robustness and horizontal pleiotropy, MR‐Egger regression and MR pleiotropy residual sum and outlier test were conducted.

Results

In meta‐analysis, childhood asthma was associated with an increased risk of T1DM (HR = 1.30, 95% CI 1.05–1.61, P = .014), whereas T1DM was not associated with the risk of asthma (HR = 0.98, 95% CI 0.64–1.51, P = .941; OR = 0.84, 95% CI 0.65–1.08, P = .168). MR analysis indicated increased genetic risk of T1DM in children with asthma (OR = 1.308; 95% CI 1.030–1.661; P = .028). Analysis using the IVW method indicated no association between T1DM and genetic risk of asthma (OR = 1.027, 95%CI 0.970–1.089, P = .358).

Conclusion

Both meta‐analysis and MR study suggested that childhood asthma was a risk factor for T1DM. No epidemiological or genetic evidence was found for an association of T1DM with asthma incidence. Further studies could be carried out to leverage this newfound insight into better clinical and experimental research in asthma and T1DM.
Network‐based biostratigraphy for the late Permian to mid‐Triassic Beaufort Group (Karoo Supergroup) in South Africa enhances biozone applicability and stratigraphic correlation
Authors: Viglietti Pia A. , Rojas Alexis , Rosvall Martin , Klimes Brady , Angielczyk Kenneth D.
Published: September 2022

The Permo‐Triassic vertebrate assemblage zones (AZs) of South Africa's Karoo Basin are a standard for local and global correlations. However, temporal, geographical and methodological limitations challenge the AZs reliability. We analyse a unique fossil dataset comprising 1408 occurrences of 115 species grouped into 19 stratigraphic bin intervals from theCistecephalus,Daptocephalus,Lystrosaurus declivisandCynognathusAZs. Using network science tools we compare six frameworks: Broom, Rubidge, Viglietti, Member, Formation, and one suggesting diachroneity of theDaptocephalus/LystrosaurusAZ boundary (Gastaldo). Our results demonstrate that historical frameworks (Broom, Rubidge) still identify the Karoo AZs. No scheme supports theCistecephalusAZ, and it probably comprises two discrete communities. TheLystrosaurus declivisAZ is traced across all frameworks, despite many shared species with the underlyingDaptocephalusAZ, suggesting that the extinction event across this interval is not a statistical artefact. A community shift at the upper Katberg to lower Burgersdorp formations may indicate a depositional hiatus which has important implications for regional correlations, and Mesozoic ecosystem evolution. The Gastaldo model still identifies aLystrosaurusandDaptocephalusAZ community shift, does not significantly improve recent AZ models (Viglietti), and highlights important issues with some AZ studies. Localized bed‐scale lithostratigraphy (sandstone datums), and singleton fossils cannot be used to reject the patterns shown by hundreds of fossils, and regional chronostratigraphic markers of the Karoo foreland basin. Metre‐level occurrence data suggests that 20–50 m sampling intervals capture Karoo AZs, unifying the use of metre‐level placements of singleton fossils to delineate biozone boundaries and make regional correlations.
The relationship between shame, perfectionism and Anorexia Nervosa: A grounded theory study
Authors: Howard Tina L. M. , Williams Marc O. , Woodward Debbie , Fox John R. E.
Published: September 2022

Objectives

The aim of this study was to explore the potential relationship between shame, perfectionism and Anorexia Nervosa (AN) and their impact on recovery from AN.

Method

Semi‐structured interviews were conducted with 11 people currently accessing services for AN. Interviews were transcribed and analysed using constructivist‐grounded theory methodology.

Results

A model was developed which found a vicious cycle between shame and perfectionism. Participants tried to alleviate their feelings of shame by striving for perfectionism, however failing caused them more shame.

Participants who disclosed childhood trauma believed their shame preceded their perfectionism. Participants who did not disclose trauma either believed their perfectionism preceded shame or they were unsure of which occurred first.

Participants' responses suggested the following pathways from perfectionism to AN: needing goals; the need for a perfect life including a perfect body and AN being something they could be perfect at. The pathways identified between shame and AN entailed mechanisms via which AN could be used to escape shame, either by seeking pride through AN, seeking to numb shame through AN, seeking to escape body shame and punishing the self. AN was found to feed back into shame in two ways: when people had AN they felt ashamed when they broke their dietary rules, and also simultaneously people felt ashamed of their AN as they were not able to recover.

Shame and perfectionism influenced one another in a cyclical pattern, in which shame drove perfectionism and not attaining high standards led to shame. Shame and perfectionism also impacted on recovery in several ways. AN functioned to numb participants' emotions, becoming part of their identity over time. AN also brought respite from a constant striving towards perfectionism. The need for a perfect recovery also influenced their motivation to engage in treatment, and fear of a return of strong emotions was another deterrent to recovery.

Conclusion

The findings of this paper show perfectionism and shame to both be important in the aetiology and maintenance of AN and to have an impact on recovery from AN.
Mechanisms of development and progression of pancreatic neoplasms
Authors: Furukawa Toru
Published: September 2022

Pancreatic ductal adenocarcinoma (PDAC) develops via dysplastic changes in the epithelia graded as low‐ and high‐grade with accumulation of molecular alterations. Constitutive activation of mitogen‐activated protein kinase (MAPK) contributed by attenuation of DUSP6 plays a key role in sustaining PDAC. Active MAPK induces various molecules that function as effectors to sustain PDAC. AURKA and SON are downstream effectors that contribute substantially to the proliferation and survival of PDAC cells and are potentially useful as therapeutic targets. Active MAPK also promote microRNAs that modulate the proliferation of PDAC cells and are useful as diagnostic markers. Familial pancreatic cancer kindreds in Japan show various germline mutations supposed to increase a pancreatic cancer risk. Intraductal papillary mucinous neoplasms (IPMNs) consist of dilated ducts lined by papillary neoplastic epithelia of various shapes and varying grades of atypia. Various papillae of IPMNs are classified into four subtypes that are associated with clinicopathological features, including patient prognosis. GNAS is a specific driver gene for the development of IPMN through gain‐of‐function mutations. Tracing of molecular alterations has elucidated the mechanism of progression of IPMN from dysplasia to carcinoma, as well as one type of papillae. Intraductal tubulopapillary neoplasms belong to a distinct class of pancreatic neoplasms.
Metabolic signature of spent culture media shows lipid metabolism as a determinant of pregnancy outcomes
Authors: de Oliveira Fernandes Gabriela , de Lima Camila Bruna , Fidelis Andrei Antonioni Guedes , Milazzotto Marcella Pecora , Dode Margot Alves Nunes
Published: September 2022

In the present study, we investigated the spent culture media of in vitro produced (IVP) bovine embryos which did (group Pregnant) or did not (group Non‐pregnant) establish pregnancy after transfer. For that purpose, IVP embryos on D5 were transferred to individual droplets for the last 48 h of culture. Embryos at the blastocyst stage were then transferred to synchronized recipients, while respective culture media drops were collected and evaluated individually. The list of metabolites present in spent culture media was obtained by electrospray ionization mass spectrometry (ESI‐MS) and analysed with Metaboanalyst® to characterize the metabolic profile of each group. The spectrometric analysis showed that pathways related to lipid metabolism, particularly fatty acids degradation via beta‐oxidation, were more present in the Pregnant group whereas no significant pathway was identified in the group Non‐pregnant. By using this method, we were able to identify a metabolic signature in culture media that allows for a better comprehension of preferential metabolic routes taken by the most viable embryos. These findings offer great insights into the biochemistry of embryo development and reveal a potential target for the development of better‐quality IVP systems, as well as tools to identify bovine embryos with greater chances to establish and maintain pregnancy.
A Bayesian Model for Estimating Sustainable Development Goal Indicator 4.1.2: School Completion Rates
Authors: Dharamshi Ameer , Barakat Bilal , Alkema Leontine , Antoninis Manos
Published: September 2022

Estimating school completion is crucial for monitoring Sustainable Development Goal (SDG) 4 on education. The recently introduced SDG indicator 4.1.2, defined as the percentage of children aged 3–5 years above the expected completion age of a given level of education that have completed the respective level, differs from enrolment indicators in that it relies primarily on household surveys. This introduces a number of challenges including gaps between survey waves, conflicting estimates, age misreporting and delayed completion. We introduce the Adjusted Bayesian Completion Rates (ABCR) model to address these challenges and produce the first complete and consistent time series for SDG indicator 4.1.2, by school level and sex, for 164 countries. Validation exercises indicate that the model appears well-calibrated and offers a meaningful improvement over simpler approaches in predictive performance. The ABCR model is now used by the United Nations to monitor completion rates for all countries with available survey data.
South Africa's titanium industrial policy: A product space perspective
Authors: De Bruyne Karolien , Bam Wouter , Engelbrecht Denis
Published: September 2022

South Africa is a globally significant player in the titanium raw mineral production industry but does not play a large role in its downstream mineral processing. Since downstream activities generate much higher value added, the government has sought to support the end‐to‐end titanium value chain to capture more value from raw titanium before export through ‘beneficiation’‐related policies. This paper applies the input–output product space methodology to generate an overview of those sub‐sectors within the titanium value chain that are likely to support long‐term economic growth in South Africa. We then evaluate whether the selected global value chain activities are supported by the current industrial policy and/or whether a focus on currently excluded global value chain activities is recommended. Our results confirm that although beneficiation appears to make sense in the titanium industry in South Africa, it should (from a product space perspective) be applied neither automatically nor sequentially moving down the value chain. The paper concludes with the shortcomings of the approach and various avenues for future research.
Orofacial myofunctional assessment and quality of life of individuals with Parkinson's disease
Authors: de Araújo Sílvia Regina Siqueira , Castelo Paula Midori , Said Angélica de Veiga , Fernandes João Paulo Santos , Neves Carolina Ribeiro , Diaféria Giovana Lúcia Azevedo , Bommarito Silvana
Published: September 2022

Objectives

To characterize orofacial myofunctional structures of elders with Parkinson's disease (PD) and examine the relationship with the stages of PD, pharmacotherapy, and quality of life.

Methods

PD Group with 45 elders and a control group (CG) of 10 healthy elders of both sexes were included (60–86 years). Structured interviews, medical records, and clinical examination gathered information on health aspects such as the use of drugs, Hoehn & Yahr stages 1–4, and oral health status. The Mini‐Mental State Examination, Parkinson's Disease Questionnaire, and Orofacial Myofunctional Evaluation with Scores for Elders were applied.

Results

Better oral health status was found in participants diagnosed as Hoehn & Yahr stage 1 compared to the later stages. OMES‐Elders scores for appearance/posture, mobility, breathing, and speech functions were different between groups, and decreased overall OMES‐Elders was observed across the Hoehn & Yahr stages. A higher number of masticatory cycles was required for chewing and ingestion of the test food in the PD group compared to CG (p < .05). Significant differences were found in the mobility and daily living activities domains and an overall score of QoL between the Hoehn & Yahr stages 1 and 4, and worst orofacial functioning was accompanied by the worst self‐perception of QoL in the communication domain (rho = −0.32; p = .034). The use of xerogenic drugs did not affect the OMES‐Elders swallowing domain.

Conclusion

Worse dental condition and performance of orofacial functions was observed in the elders with PD as the disease progresses, and poorer orofacial performance negatively affects their perception of communication skills.
Transfusión de plaquetas en trombocitopenia inmune: revisión del estado del arte
Authors: Frías Ordóñez Juan Sebastián
Published: September 2022

La trombocitopenia inmune es un trastorno autoinmunitario que lleva a la destrucción de las plaquetas y a recuentos plaquetarios bajos. Las trasfusiones de plaquetas son necesarias para prevenir las complicaciones hemorrágicas, y la falla en la obtención de una cantidad adecuada de plaquetas circulantes afecta la supervivencia. Mediante la transfusión de plaquetas se puede limitar el sangrado, pero de modo transitorio (por algunas horas), al punto de llegar a requerirse trasfusiones a repetición. Cada vez se ha escrito más acerca del uso de trasfusión de plaquetas en pacientes hospitalizados con trombocitopenia inmune; pero sigue siendo controversial, y se cree que su beneficio clínico podría estar limitado por la supervivencia más corta de las plaquetas transfundidas. No obstante, se resalta que su uso, en la mayoría de las ocasiones, está fuera de las indicaciones, por lo que se planteó como objetivo revisar el estado del arte de las transfusiones plaquetarias en trombocitopenia inmune en población adulta, haciendo hincapié en los desenlaces intrahospitalarios.
Enfoque clínico y terapéutico de la encefalitis autoinmune
Authors: Martínez Reyes Andrea , García Cifuentes Elkin Román , Torres Camacho Isabel , Peralta Uribe Jose Luis , Santana Porras Julian , Millán Pérez Sonia Patricia
Published: September 2022

Introducción: La encefalitis autoinmune es una condición inflamatoria del cerebro cuya incidencia aumentó notoriamente durante 2010-2020, y sus manifestaciones psiquiátricas requieren un abordaje interdisciplinario entre el psiquiatra y el neurólogo. Objetivo: Presentar una revisión narrativa acerca del abordaje diagnóstico y terapéutico en la encefalitis autoinmune. Métodos: Revisión narrativa de los artículos más relevantes en el área en las bases de datos Medline, Scopus y Embase. Resultados: La encefalitis autoinmune comprende un amplio espectro de síntomas neurológicos y psiquiátricos: psicosis, cambios comportamentales, déficits cognitivos y disminución del nivel de conciencia. En el análisis diagnóstico es fundamental considerar una patología autoinmune subyacente y descartar condiciones infecciosas, metabólicas y vasculares. Actualmente, los criterios diagnósticos apoyan el reconocimiento de esta patología e incluyen el estudio con electroencefalograma, resonancia magnética, análisis del líquido cefalorraquídeo y pruebas de autoanticuerpos antineuronales, ya disponibles en Colombia. El tratamiento inmunosupresor debe iniciarse lo antes posible para evitar la aparición de complicaciones graves y se asocia con un mejor pronóstico. Conclusiones: Un óptimo abordaje clínico basado en los criterios diagnósticos definidos es fundamental para administrar tempranamente un manejo inmunoterapéutico, ya que ha demostrado mejorar significativamente las tasas de supervivencia en esta enfermedad.
Exploring a Variant of PTC 4-2013 for Real-Time Performance Monitoring of Fossil Fuel Power Plants
Authors: Staller Joseph M. , Craven Robert P.M. , Idem Stephen , Munukutla Sastry , Kirkpatrick Keith , Benton Dudley , Eisenstadt Susan , Kopperstad Karsten , Leedy Seth , McHale Joe , Licata Anthony , Andrei Dan
Published: September 2022

This paper describes a real-time performance-monitoring method based on PTC 4-2013 that was developed for determining and reporting the annual heat rate for fossil fuel power plants. Unlike for the PTC 4 test, the coal composition is typically not known in real-time, so the procedure uses a modified output-loss approach applied to a control volume that closely conforms to the boiler. A calibration approach utilizes an ultimate analysis to describe the coal being burned during the calibration, while holding the plant load and other factors steady. This permits the calculation of correction factors used during real-time performance monitoring. Based on several assumptions that are justified within, a real-time estimate of coal composition is obtained. The losses are calculated in a similar manner to PTC 4-2013. However, the losses are expressed on a per-pound of as-fired coal basis, as opposed to a percentage of higher heating value of the coal, which is not known in real-time.
A Novel Generalized Predictive Control Strategy With Improved Time Domain Performance
Authors: He Ning , Li Shang , Hao Wenbin , Xu Gongbo , Liu Liqiang
Published: September 2022

Due to the ability of handling the coupling property of multivariable control system, generalized predictive control (GPC) has been widely employed in process industry. However, the existing GPC method normally utilizes the frequency domain indices in the design procedure, which is not intuitive to the industrial end users. Therefore, a new GPC method with improved time domain performance is proposed for multiple-input-multiple-output system. First, the slope and rate of change of the slope of the system outputs are considered as two new weighting terms in the cost function of GPC such that the dynamic characteristics of the system can be better considered in the optimal control problem of the controller. Second, given the modified cost function, the resultant GPC algorithm is developed to improve the time domain performance of the system. Third, the convergence and stability of the closed-loop system under the proposed method are theoretically proved. Finally, the experimental results based on the variable air volume (VAV) air conditioning system show that the time domain performance indices, including overshoot and settling time, of the proposed method, have been improved by 68.75% and 66.67%, compared with the traditional GPC, showing the advantages of the new GPC method.
Failure Mechanisms Driven Reliability Models for Power Electronics: A Review
Authors: Gabriel Okafor Ekene , Huitink David Ryan
Published: September 2022

Miniaturization as well as manufacturing processes that electronics devices are subjected to often results in to increase in operational parameters such as current density, temperature, mechanical load, and with potential to induce stresses that may be detrimental to device reliability. Past studies have identified some failure mechanisms common to these devices. Examples of these failure mechanisms include fatigue, electromigration, stress induced voiding, corrosion, conduction filament formation, and time-dependent dielectric breakdown. While some review activities related to reliability model development based on these failure mechanisms can be easily found in literature, to the best of our knowledge, a single review paper, which captures the reliability model progresses made over the past four decades across these failure mechanisms in comparison with Standards such as Joint Electron Device Engineering Council (JEDEC) and Institute for Printed Circuits (IPC) is to the best of our knowledge lacking. To fill this gap, a detailed review of failure mechanism driven reliability models, with emphasis on physics of failure (PoF) for power electronics was carried out in this paper. Although, other failure mechanisms exist, our review is only limited to fatigue, electromigration, stress induced voiding, corrosion, conduction filament formation, and time-dependent dielectric breakdown. It was found that most reliability research modeling efforts are yet to be fully integrated into Standards.
On the Effect of Frequency Separation, Mass Ratio, Solidity, and Aerodynamic Resonances in Coupled Mode Flutter of a Linear Compressor Cascade
Authors: Schuff Matthias , Chenaux Virginie Anne
Published: September 2022

At a low mass ratio of structure to air, the work-per-cycle approach, or better known as the energy method, will lead to nonconservative results as aerodynamic coupling of modeshapes acts destabilizing. Using the p–k method to solve the aeroelastic stability equation, the effects of various structural aspects are investigated for a two-dimensional compressor cascade in subsonic and transonic flow conditions. The investigated key parameters are frequency separation, mass ratio, and solidity. Furthermore, the effect of a high frequency dependency of the aerodynamic forces is presented. Such phenomena can happen in case of aerodynamic or acoustic resonances. If the resonance peaks are close to the aeroelastic frequency, a discontinuous behavior of the frequency or damping solution can lead to a rapid destabilization of the system, once the aeroelastic frequency moves from one side to the other of the peak. In these regimes, it is crucial to have a high quality representation of the frequency-dependent generalized aerodynamic forces (GAFs) for an accurate prediction of the flutter onset.
Performance Optimization of Semi-Closed Oxy-Combustion Combined Cycle for Current and Future Blade Materials
Authors: Risimini Gabriele Pio , Martinelli Matteo , Chiesa Paolo , Martelli Emanuele
Published: September 2022

Among the technologies for carbon capture and storage (CCS) from natural gas, oxy-turbine plants are a very promising solution thanks to the high efficiency, absence of stack, and nearly 100% capture rate. This paper investigates the efficiency which can be achieved by the semi-closed oxy-combustion combined cycle (SCOC-CC) with state-of-the-art and future blade materials. In particular, the analysis considers class-H turbine superalloys with a maximum blade wall temperature of 900 °C and ceramic matrix composites with blade wall temperatures of 1300 °C. Sensitivity analyses are performed to determine the optimal pressure ratio and turbine inlet temperature. The results indicate that state-of-the-art superalloys allow the SCOC-CC to achieve 54% net electric efficiency with a 96% carbon capture rate, while ceramic matrix composite (CMC) blades boost the efficiency up to 60%. For both cases, critical factors are the high temperature gradients across the blade coatings (thermal barrier coating (TBC) for superalloy, environmental barrier coating (EBC) for CMC) and the blade thickness caused by the large heat flux exchanged between hot gases and cooling flows.
Boundary Transformation Vectors: A Geometric Method of Quantifying Attractor Deformation for Structural Health Monitoring
Authors: Sloboda Andrew R. , Kong Chin Ting
Published: September 2022

Chaotic signals have long held promise as a means of excitation in structural health monitoring applications, but methods to process the structural response and infer damage are limited in number and effectiveness. Here, an alternative geometric methodology is presented that is based on measuring the boundary deformation of a system attractor as parameters change. This technique involves sampling the boundaries of two system attractors: one with nominal parameters and one with varied parameters, and then computing boundary transformation vectors (BTVs) between them. These vectors encode information about how the system has changed. This method allows damage level as well as type/location to be simultaneously quantified in simulated structures, and represents a major step toward making chaotic excitation a more practical choice for structural health monitoring.
Heat Transfer Effect From Floating Cold Cap Motion in a Waste Glass Melter
Authors: Guillen Donna P. , Abboud Alexander W.
Published: September 2022

In this study, a computational fluid dynamics (CFD) model was developed to model the motion of a solid cold cap in a waste glass melter. Forced convection bubblers at the base of the melter release air into the molten glass, which forms large bubbles that travel upwards to the cold cap and augment heat transfer from the glass to the cold cap. The CFD model employs the Navier-Stokes equations to solve for the fluctuating flowfield using a rigid body motion dynamic fluid body interaction module. This allows for movement of the floating body in response to the bubbling forces calculated at each time step. The heat flux delivered to the cold cap by the convective bubbling is studied as a function of the bubbling rate. Results for the moving cold cap are compared with the computed heat flux trends for a stationary cold cap. The heat flux delivered to the cold cap from the glass is 25% higher for the case with the moving cold cap. The heat flux was found to be proportional to v0.6 as opposed to v0.9 (where v is the normalized bubbling rate) for the stationary cold cap.
Techno-Economic Analysis of Solar PV-Assisted Hydroponic System - A Case Study in Johannesburg, South Africa
Authors: Adedeji Paul A. , Olatunji Obafemi O. , Madushele Nkosinathi , Janse van Rensburg Nickey
Published: September 2022

Nutrient film technology-based hydroponic systems are hydrophilic. Hence, a constant water supply is essential for the optimal yield and viability of the investment. Though the national grid could power water pumps for a hydroponic system in urban areas, incessant load shedding in South Africa has significantly affected the yield. Hence, the need for an alternative power supply for these systems. This study conducted a techno-economic analysis on a proposed solar photovoltaic (PV) for a hydroponic food garden located in Johannesburg. The case study constitutes one of the Urban Agricultural Initiatives (UAI) in the city. The optimal solar-PV sizing for the hydroponic system was developed. Two scenarios for powering the hydroponic system were investigated vis-à-vis the standalone solar-PV and national grid with solar-PV and battery backup. Among other cost functions, the levelized cost of electricity (LCOE) was used to evaluate the systems. The simulations were performed using HOMER Pro tool for Microgrid Analysis to determine the profitability of the two alternative energy sources on the system. Among the two alternatives, the hybrid system offered a lower net present value (NPV) of 79, 156.74 (ZAR) and an LCOE of 0.47 (ZAR) compared with the standalone system with an NPV of 290,930.73 (ZAR) and an LCOE of 2.57 (ZAR). However, the indirect value chain of the hybrid solution is associated with environmental emissions. The results obtained from the two scenarios could be used as a model for powering other urban hydroponic systems in other geospatial locations. While system effectiveness is highly prioritized, an economical scenario that mitigates the load shedding effects and enhances the productivity of the hydroponic food garden is very vital.
Performance and Emission Characteristics of a Marine Diesel Engine Fueled by Nano-Emulsified Biodiesel Produced From Waste Vegetable Oil
Authors: Ogunkunle Oyetola , Nkosi Nsizwazonke Cedrick , Laseinde Opeyeolu Timothy
Published: September 2022

This study presents an investigation of some performance parameters and emissions characteristics of a six-cylinder submarine diesel engine operated on blends of biodiesel produced from waste vegetable oil (WVO). A heterogeneous catalyst was developed from waste eggshells via calcination 900 oC for 3 hrs. Waste vegetable oil was purified via hydrolysis to degum and reduce the free fatty acid of the oil. Biodiesel was produced from the purified WVO using the heterogeneous catalyst and methanol as alcohol. Nanoparticles were prepared from coconut shells via calcination at 900 °C for 5 hrs. Nanoemulsified fuel samples, B5 (5% biodiesel + 95% diesel), B10 (10% biodiesel + 90% diesel), and B20 (20% biodiesel + 80% diesel) were prepared from the produced biodiesel together with a constant weight of 5g of nanoparticles and 5wt% water. Engine tests were carried out under different load conditions (20%, 40%, 60%, 80%, and 100%) using nano-emulsified biodiesel blend and pure diesel. Performance characteristics such as brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), and exhaust gas temperature (EGT) were determined. The emissions measured include CO, CO2, HC, NOx. The heterogeneous catalyst was found to have 62% CaO composition. An average yield of 90.5% was obtained from biodiesel production. The CO and HC emissions were maximum for pure diesel compared to the biodiesel blends. However, there was an increase in CO2 emissions as biodiesel content increased in the fuel blends. The NOx emissions were maximum for pure diesel, with B5 showing more NOx reduction. The results showed that all the fuel blends demonstrated more suitable qualities as a substitute fuel for a diesel engine. The blended fuels are similar to diesel performance, but B20 showed maximum BTE at full load conditions.
Thermodynamic Analysis of a Self-Sufficient and Nearly Emission Free Wastewater Treatment Plant
Authors: Erguvan Mustafa , MacPhee David W. , Amini Shahriar
Published: September 2022

Effluent standards in wastewater treatment plants have been very strict due to a dramatic increase in the amount of contaminants of household and industrial wastewater. For this reason, wastewater treatment plants consume a significant amount of power in order to treat wastewater throughout the world. Since most of the power in the United States is produced by petroleum products and natural gas, greenhouse gas emission has been a severe problem. In this study, a multigeneration energy system has been developed numerically to create an energetically self-sufficient wastewater treatment plants (WWTP) with zero emission. Since the WWTP part has already been investigated in another study [1], only the oxy-fuel power generation system, which is a combination of an oxy-fuel combustion cycle with a Rankine cycle, has been modeled. In the oxy-fuel combustor, the biogas generated by anaerobic digestion process is combusted with pure oxygen and recycled CO2 to produce hot exhaust gas. The system has been developed and modelled using Engineering Equation Solver and several parameters in the power cycle have been varied so as to investigate their effects on thermodynamic efficiencies and self-sufficiency ratio. The parameters in this sensitivity study are compression ratio, turbine inlet temperature, CO2 return ratio, recycled CO2 temperature, and temperature difference in the regenerator. Energy and exergy efficiencies of the parametric study have been calculated along with the self-sufficiency ratio. The maximum results for energy and exergy efficiencies shown to be 53.7% and 52.2%, and for self-sufficiency ratio to be 130.5%. The results show that this concept has a significant potential for future deployment.
A Proof-of-Concept Study of a Novel Elasto-Hydrodynamic Seal for CO2
Authors: Lyathakula Karthik Reddy , Cesmeci Sevki , Hassan Mohammad Fuad , Xu Hanping , Tang Jing
Published: September 2022

This paper deals with numerical studies of a novel Elasto-Hydrodynamic Seal (EHD), which has been developed for supercritical CO2 (sCO2) turbomachinery applications. Current sCO2 turbomachinery suffer from high leakage rates, which is creating a major roadblock for the full realization of sCO2 power technology. The high leakage rates not only penalize the efficiencies but also create environmental concerns due to greenhouse effects caused by increased CO2 discharge to the atmosphere. The proposed novel EHD seal needs to work at elevated pressures (12–35 MPa) and temperatures (350–700 °C) with low leakage and minimal wear. The unique mechanism of such a EHD seal provides a self-regulated constriction effect to restrict the flow without substantial material contact, thereby minimizing the leakage and wear. This work utilizes a physics-based modeling approach. The flow through the gradually narrowing seal clearance is modeled by the well-known Reynolds equation in EHD lubrication theory. Whereas the deformation of the seal is modeled by using the governing equations of three-dimensional solid mechanics. As for the solution methodology, COMSOL’s Thin-Film Flow and Solid Mechanics Modules were employed with their powerful capabilities. The numerical results were presented and discussed. It was observed that the Reynolds equation fully coupled with the surface deformation was able to capture the constriction effect successfully. It was also interesting to observe that the seal leakage followed a quadratic trend with increasing pressure differential, which can become advantageous for high-pressure applications such as sCO2 power generation technology.
The pH Robustness of Bacterial Sensing
Authors: Monteagudo-Cascales Elizabet , Martín-Mora David , Xu Wenhao , Sourjik Victor , Matilla Miguel A. , Ortega Álvaro , Krell Tino
Published: September 2022

Demonstration of the pH robustness of extracytoplasmic sensing reveals a previously undescribed evolutionary mechanism that enables bacteria to monitor environmental changes under changing conditions. This mechanism includes the maintenance of the dimeric state of four-helixbundle ligand-binding domains (LBDs).
Interaction Networks Are Driven by Community-Responsive Phenotypes in a Chitin-Degrading Consortium of Soil Microbes
Authors: McClure Ryan , Farris Yuliya , Danczak Robert , Nelson William , Song Hyun-Seob , Kessell Aimee , Lee Joon-Yong , Couvillion Sneha , Henry Christopher , Jansson Janet K. , Hofmockel Kirsten S.
Published: September 2022

The soil microbiome performs many functions that are key to ecology, agriculture, and nutrient cycling. However, because of the complexity of this ecosystem we do not know the molecular details of the interactions between microbial species that lead to these important functions.
Microbial Interdomain Interactions Delineate the Disruptive Intestinal Homeostasis in Clostridioides difficile Infection
Authors: Herrera Giovanny , Arboleda Juan Camilo , Pérez-Jaramillo Juan E. , Patarroyo Manuel Alfonso , Ramírez Juan David , Muñoz Marina
Published: September 2022

Clostridioides difficile
infection represents a serious public health problem in different countries due to its high morbi-mortality and the high costs it represents for health care systems. Studies have shown the impact of this infection on intestinal microbiome homeostasis, mainly on bacterial populations.
Bacterial Growth of Uropathogenic Escherichia coli in Pooled Urine Is Much Higher than Predicted from the Average Growth in Individual Urine Samples
Authors: Hogins Jacob , Fan Ethan , Seyan Zheyar , Kusin Sam , Christie Alana L. , Zimmern Philippe E. , Reitzer Larry
Published: September 2022

Urinary tract infections (UTIs) will affect most women, can recur especially in postmenopausal women, and can become antibiotic recalcitrant.
Escherichia coli
causes most community-acquired UTIs and recurrent UTIs. Current theories of virulence, based on studies of UTI-associated
E. coli
, propose multiple virulence mechanisms and complex host-pathogen interactions.
Future of clinical trials in the delivery room: time for pragmatism
Authors: O'Donnell Colm Patrick Finbarr , Dekker Janneke , Rüdiger Mario , te Pas Arjan B
Published: September 2022

Despite increased amounts of research, most of the evidence that supports treatment of newborns in the delivery room is rated ‘low’ rather than ‘high’ quality. This assessment stems largely from a lack of evidence from clinical trials. When trials have been performed, the evidence has often been downgraded due to enrolment of small or poorly representative samples, and for lack of blinding of caregivers and outcome assessors. Delivery room trials present particular challenges when obtaining consent, enrolling participants, taking measures to limit bias and identifying appropriate outcome measures. We hope our suggestions as to how future delivery room trials could be more pragmatic will inform the design of large studies that are necessary to allow clinical practice to evolve.
Inherited causes of combined vision and hearing loss: clinical features and molecular genetics
Authors: Guimaraes Thales Antonio Cabral de , Arram Elizabeth , Shakarchi Ahmed F , Georgiou Michalis , Michaelides Michel
Published: September 2022

Combined vision and hearing loss, also known as dual sensory impairment, can occur in several genetic conditions, including ciliopathies such as Usher and Bardet-Biedl syndrome, mitochondrial DNA disorders and systemic diseases, such as CHARGE, Stickler, Waardenburg, Alport and Alstrom syndrome. The retinal phenotype may point to the diagnosis of such disorders. Herein, we aim to provide a comprehensive review of the molecular genetics and clinical features of the most common non-chromosomal inherited disorders to cause dual sensory impairment.