bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous detection of multiple bacterial and viral aquatic pathogens using a fluorogenic loop‐mediated isothermal amplification‐based dual‐sample microfluidic chip
Authors: Zhou Qian‐Jin , Lu Jian‐Fei , Su Xiu‐Rong , Jin Jing‐Lei , Li Shang‐Yang , Zhou Yan , Wang Lei , Shao Xin‐Bin , Wang Yao‐Hua , Yan Mao‐Cang , Li Ming‐Yun , Chen Jiong
Published: December 2020

Rapid and user‐friendly diagnostic tests are necessary for early diagnosis and immediate detection of diseases, particularly for on‐site screening of pathogenic microorganisms in aquaculture. In this study, we developed a dual‐sample microfluidic chip integrated with a real‐time fluorogenic loop‐mediated isothermal amplification assay (dual‐sample on‐chip LAMP) to simultaneously detect 10 pathogenic microorganisms, that is Aeromonas hydrophila, Edwardsiella tarda, Vibrio harveyi, V. alginolyticus, V. anguillarum, V. parahaemolyticus, V. vulnificus, infectious hypodermal and haematopoietic necrosis virus, infectious spleen and kidney necrosis virus, and white spot syndrome virus. This on‐chip LAMP provided a nearly automated protocol that can analyse two samples simultaneously, and the tests achieved limits of detection (LOD) ranging from 100 to 10–1 pg/μl for genomic DNA of tested bacteria and 10–4 to 10–5 pg/μl for recombinant plasmid DNA of tested viruses, with run times averaging less than 30 min. The coefficient of variation for the time‐to‐positive value was less than 10%, reflecting a robust reproducibility. The clinical sensitivity and specificity were 93.52% and 85.53%, respectively, compared to conventional microbiological or clinical methods. The on‐chip LAMP assay provides an effective dual‐sample and multiple pathogen analysis, and thus would be applicable to on‐site detection and routine monitoring of multiple pathogens in aquaculture.
Blue light protection, part II—Ingredients and performance testing methods
Authors: Coats Jahnna G. , Maktabi Briana , Abou‐Dahech Mariam S. , Baki Gabriella
Published: December 2020

Background

There are numerous cosmetic ingredients that have been identified to have blue light protection benefits. The urge to learn more about blue light protection claims has led to several substantiation test methods that can be utilized by companies to prove product efficacy.

Aims

Part II of this article provides up‐to‐date information on cosmetic ingredients that can provide protection from blue light, and methods companies can use to substantiate blue light protection claims.

Methods

An Internet search was completed using the Google Scholar database and a cosmetic ingredient supplier database (UL Prospector) for ingredients and relevant literature.

Results

Multiple ingredient categories, for example, algae‐derived ingredients, UV filters, botanical extracts, antioxidants, and vitamins, are available on the market to fight against blue light‐induced skin damage. There is not a formal standardized method to test for blue light protection; however, spectrophotometers, imaging devices, measuring oxidative stress, and visual evaluations are some of the methods being used today.

Conclusions

The number of ingredients launched for blue light protection and new methods developed to test products for blue light protection claims is expected to increase in the near future as we are learning more about the mechanism of damage that occurs in the skin upon blue light exposure.
Microneedle systems as medical devices for esthetical treatments: A risk assessment approach
Authors: del Rio Luis Alberto , Baeza David , Salazar Nuria
Published: December 2020

Background

Microneedling devices are being used as a surgical technique without a clear regulatory category. They can become dangerous considering that these kind of devices can easily be bought and used by nonqualified people.

Aims

Our aim has been to demonstrate that microneedling devices used in dermatological surgery are Medical Devices according to the current regulations.

Patients/Methods

After a thorough review in the European Union and USA medical device classification, we consider microneedling systems as Class II (US) or IIa (EU).

Results

Therefore, they must follow the regulations established for medical devices. A risk assessment has also been made, in which the technical and scientific deficiencies in their design and manufacturing have been recognized in addition to including compulsory information for the regulatory agencies and most importantly for the final user.

Conclusion

It can be concluded that microneedling is an interesting tool in dermatology although more information related to its safety needs to be submitted. In addition, its use by nonprofessional people does not guarantee the safety of the user.
The anti‐tumor effects of imidazolium salts on oral squamous cell carcinoma
Authors: de Campos Paloma Santos , Menti Luiza Deitos , Pazutti Luise , Bortoli Natália Ângela , Ferreira Leonildo Alves , van Wyk Juanita Lizele , Darkwa James , Schrekker Henri Stephan , Lamers Marcelo Lazzaron
Published: December 2020

Background

Imidazolium salts (IS), ionic derivatives of neutral imidazoles, have properties that can be adjusted by structural modifications to their cations and anions, which makes this particular class of compounds a promising option for developing biologically active compounds. The anti‐tumor effects of the IS 1‐n‐butyl‐3‐methylimidazolium chloride (C4MImCl), 1‐n‐decyl‐3‐methylimidazolium chloride (C10MImCl), 1‐n‐hexadecyl‐3‐methylimidazolium chloride (C16MImCl), 1‐n‐hexadecyl‐2,3‐dimethylimidazolium chloride (C16M2ImCl), 1‐n‐octadecyl‐3‐methylimidazolium chloride (C18MImCl), 1‐n‐hexadecyl‐3‐methylimidazolium methanesulfonate (C16MImMeS), and 1‐n‐hexadecyl‐2,3‐ dimethylimidazolium methanesulfonate (C16M2ImMeS) on oral squamous cell carcinoma (OSCC) have been studied here.

Methods

Oral squamous cell carcinoma cells (CAL27) were incubated with increasing IS doses and then submitted to proliferation (2D), cell death (2D) and spheroid assay (3D).

Results

The IS anti‐tumor effect was dependent on both its N‐alkyl chain length and anion, whereby C16MImCl proved to be more effective in combination for inhibiting cell proliferation and cell‐cell adhesion, outperforming the methylated C16M2ImCl derivative and, most importantly, the gold standard—cisplatin. In addition, C16MImCl had little effect on keratinocytes and more pronounced effects on more aggressive tumor cells. It also exhibited similar effects on inducing cell death when compared to Cisplatin. This compound spread to a greater area of the tumor sphere and produced an enhanced number of apoptotic and necrotic cells in the tumor cell line, demonstrating only a small rise in the healthy cells.

Conclusion

These data indicate that the effect of C16MlmCl on OSCC is promising, as it is selective for cancer cells.
Adherence rates and risk factors for suboptimal adherence to secondary prophylaxis for rheumatic fever
Authors: Kevat Priya M , Gunnarsson Ronny , Reeves Benjamin M , Ruben Alan R
Published: December 2020

Aim

Secondary prophylaxis with 3–4 weekly benzathine penicillin G injections is necessary to prevent disease morbidity and cardiac mortality in patients with acute rheumatic fever (ARF) and rheumatic heart disease (RHD). This study aimed to determine secondary prophylaxis adherence rates in the Far North Queensland paediatric population and to identify factors contributing to suboptimal adherence.

Methods

A retrospective analysis of data recorded in the online RHD register for Queensland, Australia, was performed for a 10‐year study period. The proportion of benzathine penicillin G injections delivered within intervals of ≤28 days and ≤35 days was measured. A multi‐level mixed model logistic regression assessed the influence of age, gender, ethnicity, suburb, Accessibility and Remoteness Index of Australia class, number of people per dwelling, Index of Relative Socio‐economic Advantage and Disadvantage, Index of Education and Occupation, year of inclusion on an ARF/RHD register and individual effect.

Results

The study included 277 children and analysis of 7374 injections. No children received ≥80% of recommended injections within a 28‐day interval. Four percent received ≥50% of injections within ≤28 days and 46% received ≥50% of injections at an extended interval of ≤35 days. Increasing age was associated with reduced delivery of injections within 35 days. Increasing year of inclusion was associated with improved delivery within 28 days. The random effect of individual patients was significantly associated with adherence.

Conclusions

Improved timely delivery of secondary prophylaxis for ARF and RHD is needed as current adherence is very low. Interventions should focus on factors specific to each individual child or family unit.
Bacteria cultured from the gut ofMeccus pallidipennis(Hemiptera: Reduviidae), a triatomine species endemic to Mexico
Authors: Jiménez‐Cortés J. G. , García‐Contreras R. , Bucio‐Torres M. I. , Cabrera‐Bravo M. , López‐Jácome L. E. , Franco‐Cendejas R. , Vences‐Blanco M. O. , Salazar‐Schettino P. M.
Published: December 2020

The study of intestinal microbiota in vector insects like triatomines is paramount in parasitology because many parasitic species inhabit the vector's gut. Although knowledge on the gut microbiota in various vectors of the parasitic flagellateTrypanosoma cruzihas grown, research efforts have focused on South American triatomines. This study reports the isolation of bacterial microbiota in the anterior and posterior gut ofMeccus pallidipennis(a triatomine species endemic to Mexico) by culture, as well as its identification by phenotypic and biochemical tests and its quantification by counting colony‐forming units. The study was performed on fifth‐instar nymph and adult specimens ofM. pallidipennis, either laboratory‐bred or collected in the field and either infected or not withT. cruzi. Overall, 17 bacterial species were identified, with the generaBacillusandStaphylococcusbeing the most prevalent regardless of the origin of the insects. No differences were observed in the number of bacterial species in the gut of laboratory‐bred and field‐collected insects, neither with respect to life stage or infection status. In general, the Shannon‐Weaver diversity index was higher in non‐infected insects than in infected ones. Further studies using non‐culture methods are required to determine whether bacterial species diversity is modified by laboratory breeding.
Racialization in nursing: Rediscovering Antonio Gramsci’s concepts of hegemony and subalternity
Authors: Racine Louise
Published: December 2020

Although Gramsci's notions of hegemony and subalternity may seem outdated in this 21st century, a critical examination of the literature shows that these concepts apply in this global pandemic and political context. Racialization is a form of structural violence. In this paper, I also explore Gramsci's’ notion of engaged intellectuals to support the idea of social and political activism in nursing. Nurse scholars call for the decolonization of the discipline. Gramsci's philosophical approach to hegemony can be extended to racialization in nursing. Gramsci's notions of civil society and state can help nurses to see the structures that create racism in nursing and society.
Deciduous and evergreen oaks show contrasting adaptive responses in leaf mass per area across environments
Authors: Sancho‐Knapik Domingo , Escudero Alfonso , Mediavilla Sonia , Scoffoni Christine , Zailaa Joseph , Cavender‐Bares Jeannine , Álvarez‐Arenas Tomás Gómez , Molins Arántzazu , Alonso‐Forn David , Ferrio Juan Pedro , Peguero‐Pina José Javier , Gil‐Pelegrín Eustaquio
Published: December 2020

Increases in leaf mass per area (LMA) are commonly observed in response to environmental stresses and are achieved through increases in leaf thickness and/or leaf density. Here, we investigated how the two underlying components of LMA differ in relation to species native climates and phylogeny, across deciduous and evergreen species.

Using a phylogenetic approach, we quantified anatomical, compositional and climatic variables from 40 deciduous and 45 evergreen Quercus species from across the Northern Hemisphere growing in a common garden.

Deciduous species from shorter growing seasons tended to have leaves with lower LMA and leaf thickness than those from longer growing seasons, while the opposite pattern was found for evergreens. For both habits, LMA and thickness increased in arid environments. However, this shift was associated with increased leaf density in evergreens but reduced density in deciduous species.

Deciduous and evergreen oaks showed fundamental leaf morphological differences that revealed a diverse adaptive response. While LMA in deciduous species may have diversified in tight coordination with thickness mainly modulated by aridity, diversification of LMA within evergreens appears to be dependent on the infrageneric group, with diversification in leaf thickness modulated by both aridity and cold, while diversification in leaf density is only modulated by aridity.
The Zenga Equality Curve: A New Approach to Measuring Tax Redistribution and Progressivity
Authors: Greselin Francesca , Pellegrino Simone , Vernizzi Achille
Published: December 2020

We adopt and extend the new Zenga inequality curve to study the degree of progressivity as well as the redistributive and re‐ranking effects of a personal income tax system. Moreover, we also establish the social welfare implications of these new inequality measures and compare them with the classical approach based on the Lorenz curve and the Gini coefficient. The Zenga methodology is based on comparing the mean income of the poorest income earners with the mean income of the remaining richest part of the population. To the best of our knowledge, this approach has never been applied to study the effects produced by a personal income tax. To fill this gap in the literature, we prove that the elasticity of the Zenga uniformity curve with respect to the Lorenz curve is always greater than 1, thus recasting—within the new paradigm—the most important curves and the corresponding tax indices, such as the Reynolds–Smolensky, the Kakwani, and the Atkinson–Plotnick–Kakwani indices. We then derive three important inequalities for the newly developed measures, inspired by the well‐known properties of the classical approach. Finally, we show how some information, which could remain unnoticed by the cumulative approach inherent to the Lorenz curve, is instead highlighted by the new methodology. The advantages of complementing the classic indices with the new ones are discussed through an application to the Italian tax system.
Three novel HLA alleles detected in Spanish donors, HLA‐A*03:01:93, ‐C*07:18:08, and ‐C*03:03:01:41
Authors: Marin Rubio Luis Alberto , Rada Ramon , Ontañon Jesús
Published: December 2020

Three novel HLA class I alleles, HLA‐A*03:01:93, ‐C*07:18:08, and ‐C*03:03:01:41, detected in Spanish individuals.
Encephalitis and meningitis in Western Africa: a scoping review of pathogens
Authors: Rezaei Shawheen J. , Mateen Farrah J.
Published: December 2020

Objective

To give an overview of the recently reported literature on the aetiologies of meningitis and encephalitis in western sub‐Saharan Africa.

Methods

We conducted a scoping review following PRISMA guidance on published meningitis and encephalitis cases in the 16 countries of the United Nations‐defined western sub‐Saharan African region as identified in cohort studies, case series, and case reports, published 01/01/2000–08/01/2020, and available in four databases in August 2020 with an abstract in English, French or Italian.

Results

There were 38 distinct pathogens identified from 91 cohort studies’ data and 48 case reports or case series’ data. In cohort‐level data, the majority of cases were caused by Neisseria meningitidis (71.5%), Streptococcus pneumoniae (17.6%) and Haemophilus influenzae (7.3%). In case report‐ and case series‐level data, 40.5% of patients were <18 years old, 28.6% were female, and 28.6% were known to be immunocompromised. The case fatality rate was 39.3%. The most commonly reported pathogens among immunocompetent patients were Salmonella species (13 cases) and Ebola virus (9 cases), and the most commonly reported pathogen among immunocompromised patients was Cryptococcus neoformans (18 cases). Most cohort cases (52.3%) derived from Niger followed by Burkina Faso (28.6%). Most cases from single reports or series were reported from Nigeria (21.4%), Mali (20.2%) and Burkina Faso (19.0%).

Conclusions

Given the small number of pathogens reported, our findings underscore the need to better screen, diagnose and monitor populations in western sub‐Saharan Africa for additional CNS pathogens, including those posing significant outbreak risks.
Computed tomography with Hounsfield unit assessment is useful in the diagnosis of liver lobe torsion in pet rabbits (Oryctolagus cuniculus)
Authors: Daggett Alexis , Loeber Samantha , Le Roux Alexandre B. , Beaufrere Hugues , Doss Grayson
Published: December 2020

Clinical signs of liver lobe torsion in rabbits are often nonspecific and mimic those that are also generally detected with gastrointestinal stasis. Nonspecific clinical signs may result in pursuit of full‐body imaging such as computed tomography (CT). The aim of this multicenter, retrospective, case series study was to describe CT findings of liver lobe torsion in a group of rabbits. Computed tomography studies of six rabbits with confirmed liver lobe torsion by surgery or necropsy were evaluated. The caudate liver lobe was affected in six out of six rabbits and was enlarged, rounded, hypoattenuating, heterogeneous, and minimally to noncontrast enhancing, with scant regional peritoneal effusion. Precontrast, mean Hounsfield units (HU) of the torsed liver lobe (39.3 HU [range, 24.4‐48.1 HU]) were lower than mean HU of normal liver (55.1 HU [range, 49.6‐60.8 HU]), with a mean torsed:normal HU ratio of 0.71 (range, 0.49‐0.91). Postcontrast, mean HU of the torsed liver lobe (38.4 HU [range, 19.7‐48.9 HU]) were also lower than mean HU of normal liver (108.4 HU [range, 84.5‐142.0 HU]), with a lower postcontrast mean torsed:normal HU ratio of 0.35 (range, 0.14‐0.48) compared to precontrast. Mean HU of torsed liver lobes had little difference pre‐ and postcontrast (postcontrast HU 1.0 times the average precontrast HU [range, 0.81‐1.1]), and contrast enhancement of the torsed liver lobes was on average 50% lower than in normal liver. Liver lobe torsion should be considered in rabbits with an enlarged, hypoattenuating, heterogeneous, minimally to noncontrast enhancing liver lobe, particularly the caudate lobe, and scant regional peritoneal effusion.
Sedimentary Dynamic and Composition of a Tidal Channel in a Tropical Hot Semi-Arid Environment, NE Brazil
Authors: Souza Ian Cerdeira de Oliveira , Maia Guilherme Augusto Mendonça , Almeida Narelle Maia de , Abreu Neto João Capistrano , Freire George Satander Sá
Published: December 2020

Tidal channels comprise a peculiar and dynamic environment. This paper aims to recognize the sedimentary distribution and composition of a tidal channel located in a semi-arid climate area in order to understand the sedimentary dynamics of the region. This region has economic and environmental importance considering that several activities are developed in the area such as; salt industry and aquaculture with shrimp farming. The results and discussion presented here on the Barra Grande Port tidal channel are based on 43 superficial samples distributed in the area, in which we analyzed the grain-size distribution and the calcium carbonate and organic matter contents. The data enabled the characterization and compartmentalization of the tidal channel on five sections and the interpretation of the sedimentary dynamics of the area. The sections present an important variation in the composition and selection. The section 1 is located in supratidal zone while sections 02, 03, 04 and 05 are in intertidal zone. The grain-size mean has a tendency to decrease toward the end of the channel as well as the gravel percentage, and the carbonate and organic matter contents. Differently, the mud content and the sorting increase toward the end of the channel and the skewness becomes more positive. In a general way, the carbonate content is high throughout the tidal channel ranging from 20 to 98% while the organic matter content is low ranging from 0 to 3%. This sedimentary distribution occurs due to the development of a hydraulic dam on section 3, causing a morphological growth of this sand bar, which acts as a natural hydraulic dam, hampering the access of the tide and consequently reducing the effectiveness of the transport, resulting in the deposition of fine sediments in the sheltered areas of the channel (sections 04 and 05). The high temperatures and low rainfall of the tropical hot semi-arid climate allowed the development of carbonate sedimentation as well as the development of anthropic activities such as salt extraction in artificial salt pans which may have influenced the low levels of organic matter.
Direct Radiative Forcing Due to Aerosol Properties at the Peruvian Antarctic Station and Metropolitan Huancayo Area
Authors: Angeles Suazo Julio Miguel , Suarez Salas Luis , Huaman De La Cruz Alex Rubén , Angeles Vasquez Roberto , Rosales Aylas Georgynio , Rocha Condor Alicia , Requena Rojas Edilson , Muñoz Ccuro Felipa , Flores Rojas Jose Luis , Abi Karam Hugo
Published: December 2020

Descrevemos os resultados do estudo da profundidade ótica do aerossol (POA) e do Forçamento Radiativo Direto (FRD) no topo da atmosfera (TOA), obtidos durante a campanha de medição e monitoramento, XXI Expedição Antártica do Peru, entre os meses de janeiro e fevereiro de 2013, e na área metropolitana de Huancayo (AMH) entre os meses de junho e julho de 2019. Na Estação Antártica Peruana Machu Picchu utilizou-se um fotômetro solar SP02-L. Tal instrumento possui 4 canais: 412 nm, 500 nm, 675 nm e 862 nm, permitindo realizar medições diretas do espectro de radiação visível. Na AMH usamos o sensor BF5, que mede a radiação direta, difusa e global em comprimento de onda curta. Os cálculos de AOD em latitudes polares variaram entre 0,0646 e 0,1061. Na AMH apresenta valor máximo de 0,58 (11 de junho) e mínimo de 0,19 (12 de junho). Determinou-se o coeficiente de Angstrom variando de 0 a 0,07, esses valores indicam a presença de partículas grandes. Na AMH varia de 0 a 1,8, que indica a presença de  aerossóis de fonte de queima de biomassa e industrial. As propriedades óticas observadas foram usadas para estimar a forçante radiativa direta por aerossóis (FRDA) no topo da atmosfera. Os resultados indicam que no King George Island, o FRDA, está entre -2 e 4 W/m2; já para a AMH a forçante radiativa direta de aerossol está entre 0 e 20 W/m2.
Maintenance Factors Affecting Increased Lutetium-177 Production
Authors: Danielsson Niklas
Published: December 2020

With lutetium (Lu-177) demand forecasted to increase following the conclusion of clinical trials and product registration in key jurisdictions, manufacturers are seeking to improve their production outputs. Naturally, the question falls to operation and maintenance of these production centers to ensure reliable supply to market. Maintenance in the radiopharmaceutical industry is a complex environment with many competing interactions between radiation safety and good manufacturing practice (GMP) requirements. With the view of doubling lutetium production by the end of 2020 and plans for continued increases over the coming years, a key question was whether the plant reliability could accommodate this increase sustainably. As plant use increases the potential frequency of failure as well as the impact of outages increases, it results in a general increase in risk. Since its development by the aviation industry in 1960s, the reliability centered maintenance (RCM) concept has seen adoption by many industries. The International Atomic Energy Agency (IAEA) developed a technical document on RCM applications in nuclear industry in May 2007 while the International Society of Pharmaceutical Engineers (ISPE) refers to the concept in their own baseline guides as well as other risk-based methods in line with international standards. Blame for reliability issues often falls at the feet of the equipment design with suggestions that wholesale redesign of equipment will solve reliability issues. Careful review of existing strategies against these baseline guidelines tells a different story with clear gaps between existing maintenance strategies and current best practice. This document details the results of that investigation, providing information on the gaps found and the systems implemented to bring maintenance strategies back in alignment with current best practice. The article also offers commentary on situations requiring compromises between those best practices defined by IAEA and ISPE.
Impact of the Stabilized Finite Element Method on Acoustic and Vortical Perturbations in Thermoacoustic Systems
Authors: Hofmeister Thomas , Hummel Tobias , Sattelmayer Thomas
Published: December 2020

This paper seeks to advance linear stability analyses of thermoacoustic systems conducted with the stabilized finite element method (sFEM). Specifically, this work analyzes and quantifies the impact of the streamline-upwind-Petrov–Galerkin (SUPG) artificial diffusion scheme on (eigen)mode shapes and damping rates of the isentropic linearized Euler equations (LEEs) in frequency space. The LEE (eigen)mode shapes are separated into acoustic and vortical perturbation components via a Helmholtz decomposition and their sensitivity on the employed stabilization scheme is investigated separately. The regions where numerical stabilization mainly acts on the perturbation types are identified and explanations for the observations are provided. A methodology is established, which allows the quantification of the impact of artificial diffusion on the acoustic field in terms of a damping rate. This nonphysical damping rate is used to determine the physically meaningful, acoustic LEE damping rate, which is corrected by the contribution of artificial diffusion. Hence, the presented method eliminates a main shortcoming of LEE eigenfrequency analyses with the sFEM and, as a result, provides more accurate information on the stability of thermoacoustic systems.
A High-Fidelity Modeling Tool to Support the Design of Oxy-Combustors for Direct-Fired Supercritical CO2 Cycles
Authors: Zambon Andrea C. , Hosangadi Ashvin , Weathers Tim , Winquist Mark , Mays Jeff , Miyata Shinjiro , Subbaraman Ganesan
Published: December 2020

The challenge in the design of oxy-combustors for direct-fired supercritical CO2 (sCO2) cycles is in addressing disparate performance metrics and objectives. Key design parameters to consider include, among others, injector design for mixing and flame stability, split of recycled CO2 diluent between injectors and cooling films, target flame temperatures to control noncondensable products, and strategies to inject the diluent CO2 for film cooling and thermal control. In order to support novel oxy-combustor designs, a high-fidelity yet numerically efficient modeling framework based on the CRUNCH CFD® flow solver is presented, featuring key physics-based submodels relevant in this regime. For computational efficiency in modeling large kinetic sets, a flamelet/progress variable (FPV) based tabulated-chemistry approach is utilized featuring a three-stream extension to allow for the simulation of the CO2 film cooling stream in addition to the fuel and oxidizer streams. Finite rate chemistry effects are modeled in terms of multiple progress variables for the primary flame as well as for slower-evolving chemical species such as NOx and SOx contaminants. Real fluid effects are modeled using advanced equations of states. The predictive capabilities of this computationally tractable design support tool are demonstrated on a conceptual injector design for an oxy-combustor operating near 30 MPa. Simulations results provide quantitative feedback on the effectiveness of the film cooling as well as the level of contaminants (CO, NO, and N) in the exhaust due to impurities entering from the injectors. These results indicate that this framework would be a useful tool for refining and optimizing the oxy-combustor designs as well as risk mitigation analyses.
The Impact of Exceptional Points on the Reliability of Thermoacoustic Stability Analysis
Authors: Schaefer Felicitas , Guo Shuai , Polifke Wolfgang
Published: December 2020

Exceptional points can be found for specific sets of parameters in thermoacoustic systems. At an exceptional point, two eigenvalues and their corresponding eigenfunctions coalesce. Given that the sensitivity of these eigenvalues to parameter changes becomes infinite at the exceptional point, their occurrence may greatly affect the outcome and reliability of numerical stability analysis. We propose a new method to identify exceptional points in thermoacoustic systems. By iteratively updating the system parameters, two initially selected eigenvalues are shifted toward each other, ultimately colliding and generating the exceptional point. Using this algorithm, we were able to identify for the first time a physically meaningful exceptional point with positive growth rate in a thermoacoustic model. Furthermore, our analysis goes beyond previous studies inasmuch as we employ a more realistic flame transfer function to model flame dynamics. Building on these results, we analyze the effect of exceptional points on the reliability of thermoacoustic stability analysis. In the context of uncertainty quantification, we show that surrogate modeling is not reliable in the vicinity of an exceptional point, even when large sets of training samples are provided. The impact of exceptional points on the propagation of input uncertainties is demonstrated via Monte Carlo computations. The increased sensitivity associated with the exceptional point results in large variances for eigenvalue predictions, which needs to be taken into account for reliable stability analysis.
A Model Reduction Method for Bladed Disks With Large Geometric Mistuning Using a Partially Reduced Intermediate System Model
Authors: Schwerdt Lukas , Panning-von Scheidt Lars , Wallaschek Jörg
Published: December 2020

Reduced order models (ROMs) are widely used to enable efficient simulation of mistuned bladed disks. ROMs based on projecting the system dynamics into a subspace spanned by the modes of the tuned structure work well for small amounts of mistuning. When presented with large mistuning, including changes of geometry and number of finite element mesh nodes, advanced methods such as the pristine-rogue-interface modal expansion (PRIME) are necessary. PRIME builds a reduced model from two full cyclic symmetric analyses, one for the nominal and one for the modified type of sector. In this paper, a new reduced order model suitable for large mistuning with arbitrary mesh modifications is presented. It achieves higher accuracy than PRIME, while saving approximately 25% computational effort during the reduction process, when using the same number of cyclic modes. The new method gains its efficiency by recognizing that large modifications from damage or repair are unlikely to be exactly the same for multiple blades. It works by building a partially reduced intermediate model: All nominal sectors are reduced using cyclic modes of the tuned structure. The single modified sector is kept as the full model. For this reason, the new reduction method is called partially reduced intermediate system model (PRISM) method. The accuracy of the PRISM method is demonstrated on an axial compressor blisk and an academic blisk geometry.
Generation of Surfaces With Isotropic and Anisotropic Wetting Properties by Curved Water Jet-Guided Laser Micromachining
Authors: Shi Yi , Cao Jian , Ehmann Kornel F.
Published: December 2020

This experimental work utilizes a newly developed method, curved water jet-guided laser micromachining, to generate microfeatures on metallic surfaces. During the process, material is removed by a high-power nanosecond laser beam, which is transmitted through a high-pressure microwater jet via total internal reflection. To achieve intricate texturing patterns, a secondary motion component is superimposed on the XY motion of the workpiece provided by the motion stage. The secondary motion is generated by deflecting the water jet trajectory by a controllable dielectrophoretic force. The induced secondary motion of the water jet cuts the processing time to one half when generating texture patterns for isotropic wetting as compared to processes with only XY motion. The ability to alter the water jet's trajectory by tens of microns at high frequencies, which is beyond the capability of conventional CNC machines, allows a wide range of different micropatterns to be generated, profoundly increasing the flexibility and efficiency of the process as compared to conventional approaches. As a demonstration, surface textures for isotropic and anisotropic behaviors are generated on stainless steel surfaces. The influence of feature spacing, motion speed (frequency), and texturing patterns on surface wettability is studied.
Energy Consideration in the Microextrusion of Aluminum Alloy 6063
Authors: Sucharitpwatskul Sedthawatt , Mahayotsanun Numpon , Bureerat Sujin , Dohda Kuniaki
Published: December 2020

This paper investigated key factors influencing energy consumption in the microextrusion process. The considered factors were: extrusion ratio (ER), die angle (α), billet length (BL), bearing length (LB), coefficient of friction (COF), and die shift (DS). The finite element simulation was carried out to determine the extrusion energy required to complete one extrusion cycle. The simulation results showed that the increased values of all the considered factors (except the die shift) led to increased extrusion energy. The results also provided percentages of energy variation in steps, which helped evaluate the energy savings with regards to the crucial other production considerations. The percentage increase in energy consumption in the lower ER values was considered higher than those of, the higher ER values. Increasing die angle (α) from 60 to 90 deg barely affected the consumed energy. The highest increase percentage of extrusion energy was found while increasing billet lengths (BL) from 3.00 mm to 4.00 mm. The lower bearing length (LB) values offered lower consumed energy. The consumed extrusion energy linearly increased with COF. The die shift (DS) did not affect the extrusion energy, but the final part geometry (curved pins). The results and analysis from this study could be used to potential energy savings and overall production costs of the microextrusion process.
A Study on Micromilling Process of Multidirectional Carbon Fiber Reinforced Plastic Composite Using Nano-Solid Dry Lubrication
Authors: Kim Jin Woo , Nam Jungsoo , Lee Sang Won
Published: December 2020

In this research, the micromilling process using nano-solid dry lubrication is studied for machining multidirectional carbon fiber reinforced plastic (MD-CFRP). For this lubrication, two kinds of graphene nanoplatelets and multiwall carbon nanotubes are used as nanoparticles. The workpiece is an MD-CFRP composite in which 10 plies of prepreg are laminated, and it consists of four carbon fiber orientations—0 deg, 45 deg, 90 deg, and 135 deg. The micromilling experiments are conducted, and the workpiece surface quality and tool wear are investigated. As a result, it is confirmed that the nano-solid dry lubrication can improve the surface quality and reduce the tool wear. In particular, larger graphene nanoplatelets (xGnP H-5) are more advantageous than smaller graphene nanoplatelets (xGnP C-750). In addition, multiwall carbon nanotubes having a tube-shape structure are less effective than graphene nanoplatelets having a two-dimensional thin sheet shape for enhancing the micromilling performances, which may be due to better lubrication effect with the graphene nanoplatelets' sliding phenomenon at the cutting region.
Guaranteeing String Stability of Multiple Interconnected Vehicles Using Heterogeneous Controllers
Authors: Farnam A. , Crevecoeur G.
Published: December 2020

In this paper, the issue of string stability for acceleration-controlled vehicles interconnected in a chain is studied. String stability is concerned with having bounded displacements between vehicles in such a way that displacements should not grow unboundedly with respect to the perturbation. Different definitions can be given to string stability: one that relates to the amplification of a local disturbance acting on one vehicle toward the whole vehicle chain, more strict definition that is related to the boundedness of vector norm of displacements with respect to the bounded vector norm of disturbance inputs acting on all vehicles; and, most practical definition that considers the boundedness of signal norm of each individual displacement with respect to the bounded signal norm of disturbance inputs acting on all vehicles, independently from the number of vehicles. It has been proven that these definitions are all impossible to be achieved using any linear homogeneous unidirectional distributed controllers with constant spacing policy. This paper proposes linear heterogeneous controllers where each vehicle behaves differently from others in a vehicle chain. We prove that three different definitions of string stability can be attained using the proposed heterogeneous controller. We propose sufficient conditions to guarantee string stability and boundedness of acceleration of each vehicle. Finally, simulation results are given to illustrate the effectiveness of proposed heterogeneous control synthesis.
Description of Unsteady Flow Characteristics in a Side Channel Pump With a Convex Blade
Authors: Zhang Fan , Chen Ke , Appiah Desmond , Yuan Shouqi , Adu-Poku Kofi Asamoah , Hong Feng
Published: December 2020

To investigate the unsteady flow characteristics in side channel pumps, the vortex structures and their evolutions in the impeller and side channel flow passages have been comprehensively studied. Systematically, three impeller schemes were designed with different ratios of convex blade height h to impeller blade length l (h/l = 0.2, 0.5, and 0.8) for detailed analysis. The findings indicated that the convex blade broadens the high-efficiency range and improves the efficiency at the best efficiency point (BEP) for scheme h/l = 0.2. Impeller scheme h/l = 0.2 records the highest vortex concentration region, scheme h/l = 0.5 displays as scattered spots, while scheme h/l = 0.8 exhibits significant flow pattern changes in the impeller. The vortex distribution area and vortex intensity in the lengthways between the impeller and side channel of h/I = 0.2 are almost analogous, but the other two impeller schemes have obvious separation and very chaotic. Although the shrinkages of axial vortexes in the impeller did not reflect on hydraulic performance, impeller schemes h/l = 0.5 and 0.8 provided an outstanding performance in reducing the pressure fluctuations. The objective of this study is to provide a theoretical basis for optimal design and analysis of strong vortex flows in side channel pumps.
Numerical Study of Supersonic Mixed Compression Air Intake With an Array of Air Jets
Authors: Gahlot N. K. , Singh N. K.
Published: December 2020

Computational study of flow physics inside the mixed compression air intake has been carried out with and without air jets (AJs) at design Mach number of 2.2. Reynolds-averaged Navier–Stokes (RANS) equations were solved with k–ω turbulence model by using commercially available software ansys. The scope of this research is to improve the flow field inside the air intake and efficiency of supersonic air intake by implementing AJs on the ramp surface. An array of AJs containing two, four, and five AJ holes, respectively, of 1 mm each has been made on the ramp surface perpendicular to the flow with equal spacing between them. The injection pressure through AJ has been kept constant for all the cases. Flow distortion (FD) and total pressure recovery (TPR) were selected to measure the performance of air intake. All the simulations have been performed at a back-pressure ratio of 6. The results obtained suggest that implementation of proper spacing between AJs can improve the performance of air intake due to the mixing of vortices generated by AJs with freestream flow. It is revealed that an array of AJs containing four holes on ramp surface works best and helps in controlling the shock-induced separation.
Effect of Cross-Flow Swirl on the Trajectory of Spray in an Annular Passage
Authors: Sikroria Tushar , Kushari Abhijit
Published: December 2020

This paper presents the experimental analysis of the impact of swirl number of cross-flowing air stream on liquid jet spray trajectory at a fixed air flow velocity of 42 m/s with the corresponding Mach number of 0.12. The experiments were conducted for 4 different swirl numbers (0, 0.2, 0.42, and 0.73) using swirl vanes at air inlet having angles of 0 deg, 15 deg, 30 deg, and 45 deg, respectively. Liquid to air momentum flux ratio (q) was varied from 5 to 25. High-speed (at 500 fps) images of the spray were captured, and those images were processed using matlab to obtain the path of the spray at various momentum flux ratios. The results show interesting trends for the spray trajectory in swirling air flow. High swirling flows not only lead to spray with lower radial penetration due to sharp bending and disintegration of liquid jet but also result in spray with large spread and spray area. Based on the results, correlations for the spray path have been proposed, which incorporates the effects of the swirl number of the air flow.
Heat Transfer in Fully Developed, Laminar Flows of Dissipative Pseudoplastic and Dilatant Fluids in Circular Conduits
Authors: Capobianchi Massimo , Cangelosi Richard , McGah Patrick M.
Published: December 2020

This paper reports the results of a numerical study that determined the Nusselt number for hydrodynamically and thermally fully developed, laminar, dissipative flows of pseudoplastic and dilatant fluids through circular conduits. Two boundary conditions were considered, constant heat flux and constant temperature. Constitutive equations were used that describe the entire flow curve, from the zero-shear rate through the infinite shear rate Newtonian regions, so that computed Nusselt numbers are valid for whatever shear rates may exist in the flow field. Nusselt numbers are reported as a function of a dimensionless shear rate parameter that establishes the region of the flow curve where the system is operating and are shown to be bound by the Newtonian and power law values. The conditions required for the system to perform at these asymptotic limits are quantified.
Pool Boiling Heat Transfer Augmentation in a Novel Aqueous Binary Mixture of Surfactants
Authors: Pawar Prashant , Najim Abdul , Acharya Anil , Pise Ashok
Published: December 2020

This paper investigates the augmentation of heat transfer during pool boiling of a novel aqueous binary mixture of surfactants. The surfactants used were sodium dodecyl sulfate (SDS) (anionic), centrimonium bromide (CTAB) (cationic), and nicotine (nonionic). The aqueous binary mixtures SDS–CTAB, CTAB–nicotine, and SDS–nicotine were prepared on the volume percentage basis. A reduction in surface tension was attained by SDS–CTAB, CTAB–nicotine, and SDS–nicotine aqueous mixtures compared to its individual aqueous surfactant solutions at their optimum concentrations. The most significant surface tension result was obtained by the novel SDS–nicotine aqueous binary system at 25:75 volume percentages. The heat transfer augmentation was investigated by studying the single bubble dynamic in the aqueous SDS–nicotine mixture. The investigation was conducted at two values of heat fluxes to probe the effect of heat flux on bubble dynamics. A significant decrement in the bubble departure diameter and a substantial increment in the release frequency was observed for the SDS–nicotine aqueous mixture at both heat fluxes. The heat transfer coefficient was found to be increased by 36.32% and 58.67% compared to saturated water at low and high heat flux, respectively.
A Practical Approach to the Design and Development of Tele-Operated Surgical Robots for Resource Constrained Environments—A Case Study
Authors: Chandrasekaran Karthik , Parameswaran Suraj , Annamraju Srikar , Chandra Sourav , Manickam Ramalingam , Thondiyath Asokan
Published: December 2020

Tele-operation has brought about a paradigm shift in the way minimally invasive surgeries are carried out. Several tele-operated robotic systems have been developed in the last three decades. In this research work, we present a practical approach for the complete design of a six degree-of-freedom (DoF) master–slave tele-operated robotic system with limited resources. This research work elaborates on the methodology followed by us for the complete system design, methods for simplifying the surgical tool design with decoupled DoF wrist utilizing stationary wire guides instead of pulleys, and method of reducing the number of balancing masses required for gravity compensation of master manipulator arms. We also demonstrate the avenues for utilizing compliant mechanism for several mechanisms of the system to reduce complexity and to mitigate the issue of biofouling. The concepts and design methodology described in this paper would serve as a starting point and design guideline for future designers of such systems in resource-constrained environments.
The Multisplit Ventilator System: Design and Function of a Regulated, Shared Ventilator System
Authors: Gaucher Donald J. , Trimble A. Zachary , Yamamoto Brennan E. , Miller Scott F. , Vossler John D. , Mahoney Reid C. , Bellomy Ryan L. , Heilbron William R. , Harvey Scott A. , Johnson Sidney M. , Puapong Devin P. , Woo Russell K.
Published: December 2020

The objective of this paper is to describe the design and function of the multisplit ventilator system (MSVS); an airflow apparatus that enables physicians to provide individualized, isolated ventilation to up to four patients using a single ventilator. Method: The study design is laboratory assessment of the ability of the MSVS to decouple the pressures and resulting tidal volumes between patient limbs in response to adverse extubation (disconnection) or endotracheal tube occlusion of one of the patients in the system. We compare the airflow decoupling of the MSVS against an existing unregulated split ventilator system (USVS) design over eight prototypical patient pairs. Simulated patient prototypes of varying size, minute ventilation requirement, and positive end-expiratory pressure (PEEP) requirement were employed. Result: Respiratory support was developed for varying simulated patient pairs using the MSVS and a USVS. The results demonstrate that patients supported with the MSVS showed significantly smaller changes to tidal volume and PEEP after extubation events, and tidal volume after occlusion events. Conclusion: It was found that the MSVS as a regulated, shared ventilator system effectively buffered simulated patients from clinical changes occurring to another patient connected to the split ventilator. This decoupling ability resulted in significantly smaller changes in delivered support when compared to existing USVS designs, which is an important patient safety consideration if deciding to support multiple patients with a single ventilator.