bluuebunny/crossref_metadata_2025 huggingface dataset:
Health literacy in action: Kaupapa Māori evaluation of a cardiovascular disease medications health literacy intervention
Authors: Carlson Teah , Moewaka Barnes Helen , McCreanor Tim
Published: February 2019

The healthcare system is complex and challenging to virtually everyone but more so to those who are marginalised, impoverished, and isolated—all factors that exacerbate health literacy barriers. This article reports on an analysis of qualitative data collected for a kaupapa Māori evaluation of a Cardiovascular Disease Medications Health Literacy Intervention. The evaluation study involved a kaupapa Māori evaluation of the effectiveness of the intervention and the discussion of wider learnings in relation to health literacy interventions with Māori and other Indigenous communities. Findings are grouped into three key themes: Whakaaro, tūrangatira, and whanaungatanga. Whakaaro—fluidity of understanding—refers to the importance of maintaining patient medication knowledge and nurturing relationships between patients and health professionals. Tūrangatira—presence—refers to changes in participation practices between patients and health professionals, as well as the limitations and outcomes of the intervention approach. Whanaungatanga—building relationships—covers the intervention structure and design and the role of the research nurse. This study highlighted that the responsibility for improving health literacy lies with everybody in making substantial systemic change. In this intervention, the focus of responsibility for building health literacy skills in patients and whānau (family) sat with front-line health professionals.
Predictors of Theory of Mind performance in bilingual and monolingual children
Authors: Buac Milijana , Kaushanskaya Margarita
Published: February 2019

Aims and objectives/purpose/research questions:

The goal of the current study was to examine whether language and Executive Function (EF) skills predict Theory of Mind (ToM) performance in bilingual and monolingual children.

Design/methodology/approach:

Participants included 44 monolingual English-speaking children ( MAge = 7.03, SD = 1.23), 44 simultaneous English-Spanish bilingual children ( MAge = 7.36, SD = 1.18), and 27 English first language (L1) bilinguals (native English speakers learning Spanish through dual immersion programs; MAge = 7.58, SD = 1.24). In the second-order false belief task, children were asked to reason about one character’s thoughts about another character’s thoughts. Three components of EF were measured: inhibition (via a flanker task); updating of working memory (via a Corsi blocks task); and shifting (via a card sort task). The Clinical Evaluation of Language Fundamentals 4th Edition indexed omnibus English language skills.

Data and analysis:

Separate logistic regression models were constructed to analyze the predictors of ToM performance for each group controlling for age, socioeconomic status, and non-verbal IQ.

Findings/conclusions:

Language ability, but not EF skills, predicted ToM performance in simultaneous bilinguals. In contrast, EF skills but not language predicted ToM performance in monolinguals and in English L1 bilinguals.

Originality:

This is the first study to show that children with distinct language acquisition histories approach verbal ToM problems differently.

Significance/implications:

It appears that the linguistic demands of the ToM task take priority for children with lower levels of target-language ability, while the cognitive demands of the task take priority for children with higher levels of target-language ability.
Numerical predictions of wind-induced buffeting vibration for structures by a developed pseudo-excitation method
Authors: Bai Yuguang , Zhang Youwei , Liu Tingting , Kennedy David , Williams Fred
Published: February 2019

A numerical analysis method for wind-induced response of structures is presented which is based on the pseudo-excitation method to significantly reduce the computational complexity while preserving accuracy. Original pseudo-excitation method was developed suitable for adoption by combining an effective computational fluid dynamic method which can be used to replace wind tunnel tests when finding important aerodynamic parameters. Two problems investigated are gust responses of a composite wing and buffeting vibration responses of the Tsing Ma Bridge. Atmospheric turbulence effects are modeled by either k–ω shear stress transport or detached eddy simulation. The power spectral responses and variances of the wing are computed by employing the Dryden atmospheric turbulence spectrum and the computed values of the local stress standard deviation of the Tsing Ma Bridge are compared with experimental values. The simulation results demonstrate that the proposed method can provide highly efficient numerical analysis of two kinds of wind-induced responses of structures and hence has significant benefits for wind-induced vibration engineering.
Secondary Endovascular Aneurysm (EVAS) Sealing in Combination With Chimney Grafts to Treat Failed Chimney EVAS
Authors: van de Velde Lennart , Zoethout Aleksandra C. , Lardenoije Jan-Willem H. P. , Reijnen Michel M. P. J.
Published: February 2019

Purpose: To describe a proximal extension of a failed chimney endovascular aneurysm sealing repair (chEVAS) using a chEVAS-in-chEVAS procedure in 2 cases with successful treatment outcome at 2-year follow-up. Case Report: Two patients with an infrarenal abdominal aortic aneurysm were treated with an elective chEVAS procedure with 1 chimney stent for a unilateral renal artery. At 18 and 24 months, respectively, both patients showed aneurysm growth with an associated decrease in proximal seal. Both patients were treated with a secondary chEVAS procedure, consisting of chimney stent-graft placement in the contralateral renal and the superior mesenteric arteries combined with proximal extension of the in situ chimney stent-graft and the Nellix stents. Two-year follow-up demonstrated successful aneurysm exclusion with a patent stent configuration. Conclusion: A type Ia endoleak after chEVAS can be successfully repaired with a chEVAS-in-chEVAS procedure.
Doing Justice to Intersectionality in Research
Authors: Rice Carla , Harrison Elisabeth , Friedman May
Published: February 2019

Intersectionality involves the study of the ways that race, gender, disability, sexuality, class, age, and other social categories are mutually shaped and interrelated through forces such as colonialism, neoliberalism, geopolitics, and cultural configurations to produce shifting relations of power and oppression. The concept does not always offer a clear set of tools for conducting social research. Instead, it offers varied strands of thought, pointing to different methodologies and methods for doing intersectional research. In this article, we trace the genealogy of intersectionality as theory and methodology to identify challenges in translating the concept into research methods, and we review debates about what we identify as three “critical movements” in the intersectionality literature, comprising contestations regarding the theory’s aims, scope, and axioms, in scholarship and research. Finally, we consider how these critical movements can offer researchers some guiding ethical principles for doing intersectionality justice in social research.
Optimizing Surgical Skills in Cardiac Surgery Residents with Cardiac Transplant in the High-Fidelity Porcine Model
Authors: Spooner Aaron J. , Faulkner Christina M. , Novick Richard J. , Kent William D. T.
Published: February 2019

Objectives

Simulation is a pivotal tool within cardiac surgery to facilitate learner growth and skill acquisition. There are many methods of simulation and it is possible to develop and implement new curricula incorporating these modalities. The objective of this paper is to describe the feasibility of a high-fidelity cardiac transplant simulation curriculum for surgical residents.

Methods

Our simulation setting was the Animal Resource Center at the University of Calgary. It was set up with 4 separate operating rooms, 2 for donor heart retrievals and 2 for heart implantations. This was done to allow 2 learners to participate with each animal, replicating the true intraoperative environment. Our teaching sessions were facilitated by 2 surgeons experienced in cardiac transplantation. In addition, we had support staff including multiple perfusionists, nurses, and anesthesia technologists.

Results

The curriculum was evaluated from many perspectives in real time throughout the simulation as well as afterward in posttest qualitative interviews with all participants. The residents readily identified the acquisition of and increased proficiency in specifically targeted surgical skills. In addition, the residents were able to practice communication, collaboration, and management. Furthermore, the simulation session and our debriefings contributed significantly to fostering a team approach.

Conclusions

The pig is an excellent preclinical model for acquiring and developing the skills necessary for human cardiac transplantation. The residents partaking in the curriculum were satisfied with the learning they received and saw value in the swine transplant curriculum. The overall curriculum was cost-effective, due to the low overall operating costs associated with it.
Income and Marital Status Interact on Obesity Among Black and White Men
Authors: Bell Caryn N. , Thorpe Roland J.
Published: February 2019

Racial disparities in obesity among men are accompanied by positive associations between income and obesity among Black men only. Race also moderates the positive association between marital status and obesity. This study sought to determine how race, income, and marital status interact on obesity among men. Using data from the 2007 to 2014 National Health and Nutrition Examination Survey, obesity was measured as body mass index ≥30 kg/m2 among 6,145 Black and White men. Income was measured by percentage of the federal poverty line and marital status was categorized as currently, formerly, or never married. Using logistic regression and interaction terms, the associations between income and obesity were assessed by race and marital status categories adjusted for covariates. Black compared to White (OR = 1.19, 95% CI [1.03, 1.38]), currently married compared to never married (OR = 1.45, 95% CI [1.24, 1.69]), and high-income men compared to low income men (OR = 1.26, 95% CI [1.06, 1.50]) had higher odds of obesity. A three-way interaction was significant and analyses identified that income was positively associated with obesity among currently married Black men and never married White men with the highest and lowest probabilities of obesity, respectively. High-income, currently married Black men had higher obesity rates and may be at increased risk for obesity-related morbidities.
Lifestyle Medicine Interventions in Patients With Advanced Disease Receiving Palliative or Hospice Care
Authors: Anandarajah Gowri , Mennillo Haran Asher , Rachu Gregory , Harder Tyler , Ghosh Jyotsna
Published: February 2019

Background: Lifestyle medicine interventions have the potential to improve symptom management, daily function, and quality of life (QOL) in patients with advanced or terminal disease receiving palliative or hospice care. The goal of this review is to summarize the current state of the literature on this subject. Methods: The authors used a broad search strategy to identify relevant studies, reviews, and expert opinions, followed by narrative summary of available information. Results: Four main categories of lifestyle interventions feature prominently in the palliative care literature: exercise, nutrition, stress management, and substance use. High-quality studies in this vulnerable population are relatively sparse. Some interventions show promise. However, most show mixed results or inadequate evidence. For some interventions, risks in this generally frail population outweigh the benefits. Clinical decision making involves balancing research findings, including the risks and benefits of interventions, with a clear understanding of patients’ prognosis, goals of care, and current physical, emotional, and spiritual state. Achieving optimum QOL, safety, and ethical care are emphasized. Conclusions: The use of lifestyle interventions in patients receiving palliative or hospice care is a complex undertaking, requiring tailoring recommendations to individual patients. There is potential for considerable benefits; however, more research is needed.
Vessel wall enhancement of a ruptured intra-nidal aneurysm in a brain arteriovenous malformation
Authors: Bhogal Pervinder , Lansley Joseph , Wong Ken , Udani Sundip D , Uff Chris , Wadley John , Kumar Atul , Matouk Charles C , Makalanda Hegoda LD
Published: February 2019

Ruptured arteriovenous malformations are a frequently encountered pathology with significant associated morbidity and mortality. Identifying and securing the rupture point is mandatory; however, this can often be difficult. Black blood vessel wall magnetic resonance imaging is a promising technique for identifying ruptured saccular aneurysms and has been used in cases of multiple aneurysms. Here we describe a case of using this imaging technique to identify the rupture point in a ruptured arteriovenous malformation with histopathological correlation.
The changing shape of hand trauma: an analysis of Hospital Episode Statistics in England
Authors: Manley Oliver W.G. , Wormald Justin C.R. , Furniss Dominic
Published: February 2019

Hospital Episode Statistics (HES) include freely accessible records of all hospital episodes in England. We analysed HES from 1998–1999 to 2014–2015 for diagnoses of hand fractures, tendon injuries, nerve injuries, blood vessel injuries, traumatic amputations and nail bed injuries. Population data were used to calculate the incidence. The overall incidence of the injuries increased from 70 to 110 per 100,000. There were especially large increases in the incidence of fractures in the over 75 years age group and nail bed injuries in the 0–14 years age group. The incidence of nerve injuries also increased. We conclude from this study that HES is a useful tool. The information from HES may help plan service provision and also highlight important clinical problems that may benefit from further research.
A Comparison of Amphibian and Reptile Diversity Between Disturbed and Undisturbed Environments of Salvatierra, Guanajuato, Mexico
Authors: Leyte-Manrique Adrian , Abel Antonio Buelna-Chontal , Miguel Alejandro Torres-Díaz , Berriozabal-Islas Christian , Maciel-Mata Carlos Alberto
Published: February 2019

Amphibians and reptiles are two groups of vertebrates that are sensitive to changes in their environment. These changes are mostly caused by human activities, which affect the abundance, composition, and distribution of these vertebrates. In this study, we compare the richness and taxonomic diversity of herpetofauna between undisturbed environments (tropical deciduous forest = TDF) and disturbed environments (corn fields = CF) near the towns of Urireo (URI) and San Nicolas de los Agustinos (SNA) in Salvatierra, Guanajuato. We recorded a total of 19 species in the two locations (4 amphibian and 15 reptile species). At the URI locality, 12 species were recorded in CF and 10 in TDF. At the SNA locality, eight species were recorded in CF and seven species in TDF. In addition, we found that overall taxonomic distinctness was greater at URI than SNA across both types of vegetation, with the highest diversity found in TDF of URI. Seven of the 19 species recorded are current allocated to some protection category of NOM-059-SEMARNAT-2010: Lithobates neovolcanicus, Kinosternon integrum, Sceloporus grammicus, Lampropeltis polyzona, Masticophis mentovarius, Salvadora bairdi, and Thamnophis melanogaster differing from other mechanisms such as the International Union for Conservation of Nature and Environmental Vulnerability Score. Our results suggest that carrying out long-term studies that include diversity and taxonomic distinctness in environments with different levels of disturbance, in addition to including characteristics of natural history, might enhance the development of more efficient conservation strategies for these vertebrates.
Analysis of the Effect of Dopamine Transporter Scan on the Diagnosis and Management in a Tertiary Neurology Center
Authors: Bhattacharjee Shakya , Paramanandam Vijayashankar , Bhattacharya Atrayee
Published: February 2019

Background and Purpose:

The dopamine transporter scan or DaT scan is abnormal in presynaptic parkinsonism but normal in nondegenerative or postsynaptic parkinsonism. In this study, we tried to ascertain the impact of DaT scan on the diagnosis and clinical management and if the semiquantitative analysis of the DaT scans has any correlation with the clinical symptoms.

Methods:

The electronic and nonelectronic records of patients of Plymouth Hospital NHS Trust, United Kingdom, from 2011 to 2015 were studied to find the indication, outcome, and the impact of the scan on the management of patients. The DaT scan results were assessed visually and semiquantitatively by the Department of Nuclear Medicine. The available data were statistically analyzed with the help of Microsoft XL2010 and GraphPad software.

Results:

A total of 258 people had DaT scan. The scan results suggested an alternate diagnosis in 50.5% of clinically diagnosed patients with Parkinson disease. Similarly, DaT scan changed the diagnosis of 40% of patients with clinical diagnosis of vascular parkinsonism, 25% of clinically diagnosed drug-induced parkinsonism, and 54% of patients with possible Lewy body dementia. Visual assessment of the DaT scan revealed that more than 60% had grade 2 abnormalities. The distribution volume ratio, a semiquantitative tool for tracer uptake, was significantly less in the patients with akinetic-rigid subtype of Parkinson disease in comparison to a tremor predominant subtype.

Conclusions:

Dopamine transporter scan had a significant impact in diagnosis and management.
Experiments with a data-public: Moving digital methods into critical proximity with political practice
Authors: Madsen Anders Koed , Munk Anders Kristian
Published: February 2019

Making publics visible through digital traces has recently generated interest by practitioners of public engagement and scholars within the field of digital methods. This paper presents an experiment in moving such methods into critical proximity with political practice and discusses how digital visualizations of topical debates become appropriated by actors and hardwired into existing ecologies of publics and politics. Through an experiment in rendering a specific data-public visible, it shows how the interplay between diverse conceptions of the public as well as the specific platforms and data invoked, resulted in a situated affordance-space that allowed specific renderings take shape, while disadvantaging others. Furthermore, it argues that several accepted tropes in the literatures of digital methods ended up being problematic guidelines in this space. Among these is the prescription to shown heterogeneity by pushing back at established media logics.
A Retrospective Analysis of Softball-Related Head and Facial Injuries Treated in United States Emergency Departments, 2013-2017
Authors: Strickland John S. , Crandall Marie , Bevill Grant R.
Published: February 2019

Background:

Softball is a popular sport played through both competitive and recreational leagues. While head and facial injuries are a known problem occurring from games, little is known about the frequency or mechanisms by which they occur.

Purpose:

To analyze head/face injury diagnoses and to identify the mechanisms associated with such injuries.

Study Design:

Descriptive epidemiological study.

Methods:

A public database was used to query data related to head/facial injuries sustained in softball. Data including age, sex, race/ethnicity, injury diagnosis, affected body parts, disposition, incident location, and narrative descriptions were collected and analyzed.

Results:

A total of 3324 head and face injuries were documented in the database over the time span of 2013 to 2017, resulting in a nationwide weighted estimate of 121,802 head/face injuries occurring annually. The mean age of the players was 21.5 ± 14.4 years; 72.1% of injured players were female, while 27.9% were male. The most common injury diagnoses were closed head injuries (22.0%), contusions (18.7%), concussions (17.7%), lacerations (17.1%), and fractures (15.1%). The overwhelming majority of injuries involved being struck by a ball (74.3%), followed by colliding with another player (8.3%), colliding with the ground or a fixed object (5.0%), or being struck by a bat (2.8%). For those injuries caused by a struck-by-ball incident, most occurred from defensive play (83.7% were fielders struck by a hit or thrown ball) as opposed to offensive play (12.3% were players hit by a pitch or runners struck by a ball). Although helmet usage was poorly tracked in the database, female players (1.3%) were significantly more likely to have been wearing a helmet at the time of injury than were male players (0.2%) ( P = .002).

Conclusion:

The present study demonstrates that a large number of head and face injuries occur annually within the United States as a result of softball play. A variety of injuries were observed, with the majority involving defensive players being struck by the ball, which highlights the need for more focus on player safety by stronger adherence to protective headgear usage and player health monitoring.
Current Connections: Controversy, Civility, and Relevance in the Executive Business Classroom
Authors: Fukami Cynthia V. , Mayer Don
Published: February 2019

To connect course material to executive MBA student workplace experiences and current events more clearly, we created an online space for students to bring up relevant workplace experiences or to post links to articles on domestic and international developments relevant to the week’s course topics and materials. The activity has brought forth significant student interactions online and in the classroom and paves the way for robust classroom discussion as well. Although we created this activity for executive MBA students, we believe it can also be used in other business courses, both graduate and undergraduate. With the experiences that executive MBA students bring, however, the interactions become especially helpful for modeling civility around difficult and divisive issues in business and society.
Neuroethical issues in cognitive enhancement: Modafinil as the example of a workplace drug?
Authors: Brühl Annette B. , d’Angelo Camilla , Sahakian Barbara J.
Published: February 2019

The use of cognitive-enhancing drugs by healthy individuals has been a feature for much of recorded history. Cocaine and amphetamine are modern cases of drugs initially enthusiastically acclaimed for enhancing cognition and mood. Today, an increasing number of healthy people are reported to use cognitive-enhancing drugs, as well as other interventions, such as non-invasive brain stimulation, to maintain or improve work performance. Cognitive-enhancing drugs, such as methylphenidate and modafinil, which were developed as treatments, are increasingly being used by healthy people. Modafinil not only affects ‘cold’ cognition, but also improves ‘hot’ cognition, such as emotion recognition and task-related motivation. The lifestyle use of ‘smart drugs’ raises both safety concerns as well as ethical issues, including coercion and increasing disparity in society. As a society, we need to consider which forms of cognitive enhancement (e.g. pharmacological, exercise, lifelong learning) are acceptable and for which groups under what conditions and by what methods we would wish to improve and flourish.
Progression of mycosis fungoides occurs through divergence of tumor immunophenotype by differential expression of HLA-DR
Authors: Murray Duncan , McMurray Jack Luke , Eldershaw Suzy , Pearce Hayden , Davies Nathaniel , Scarisbrick Julia J. , Moss Paul
Published: February 2019

Immunotherapy is a valuable treatment for many cancer patients, and there is considerable interest in understanding the mechanisms of immune evasion to guide appropriate management. Mycosis fungoides (MF) is a malignant disorder of skin-homing CD4+ T cells, and it exhibits a highly variable clinical course during which the tumor-specific immune response may be an important determinant. An unusual feature of MF is that tumor-infiltrating lymphocytes (TILs) must attempt to control a malignant cell from within their own lineage. We obtained skin biopsies and blood from 43 patients with CD4+ MF and undertook a detailed phenotypic and functional analysis of CD4+ and CD8+ T cells. Clonotypic TCRBV staining allowed delineation of malignant and reactive CD4+ subsets. CD4+ and CD8+ TILs displayed a comparable “exhausted” phenotype that was characterized by expression of PD-1 and TIGIT but retained cytotoxic activity and production of interferon-γ and interleukin-17 in early-stage disease. In contrast, tumor cells were much more heterogeneous and were divided into 3 discrete subsets based on differential expression of HLA-DR: “cold” (DR−), “exhausted” (DR+ PD-1+), and “evasive” (DR++ PD-L1+) phenotypes. Disease progression was associated with increasing divergence of the tumor phenotype away from that of TILs and reduced functional activity within TILs. These observations reveal that the phenotype and function of TIL populations are constrained at all stages of disease, whereas the tumor evolves discrete phenotypic profiles of escape during clinical progression. The findings should help to direct appropriate immunotherapeutic interventions for individual patients.
Control Principle of Thermal Spray Process
Authors: Fukumoto Masahiro
Published: February 2019

In general, an essential target in the research and development of material process lies in how to establish the controlling principle on a designated material process. In this article, the current situation in the controlling of an ordinary thermal spray process, which is a representative of a thick coating formation process using particle deposition, is reviewed. Precise observation results were introduced to the ordinary thermal spray process. In the flattening behavior of the sprayed particle onto the substrate surface, critical conditions were recognized in both the substrate temperature and the ambient pressure. A transition temperature, Tt, and a transition pressure, Pt, were defined and introduced, respectively, for these critical conditions. Three-dimensional transition curvature, by combining both the Tt and the Pt dependence, was proposed as a control principle of the thermal spray process. Furthermore, particle melting in the ordinary thermal spray process has been recognized as a negative process. To overcome this problem, a new direction in coating technology development by using non-fusion solid particles has been tried recently, which is typically called the cold spray or the aerosol deposition process. As these processes have common characteristic for all, namely, a thick coating formation by the deposition of several micron-sized particles, the present state of the art, academic/technological issues, and the prospects for the future of these coating formation processes is comprehensively summarized in this article.
Thermal Analysis of Aluminum Alloys
Authors: Larouche Daniel
Published: February 2019

Thermal analysis is applied on aluminum alloys by researchers to investigate mainly phase transformations, while it is regularly used for quality control purposes in industry. Techniques like cooling curve analysis, differential thermal analysis, differential scanning calorimetry, and isothermal calorimetry are amongst those most frequently used by scientists and engineers. These techniques will be described, and a mathematical description of the results will be developed. State-of-the-art quantification methods applied on aluminum alloys will be presented and criticized based on specific examples taken from the literature.
Micromachining of Aluminum Alloys
Authors: Rumsey Ann , Jahan Muhammad
Published: February 2019

This article provides a comprehensive overview of the machining of aluminum alloys, composites, and ceramics at micro scale. All major aspects of the micromachining of aluminum alloys including process descriptions, key research findings, applications, major challenges, and guidelines for future research have been covered in this article. Based on the literature, conventional micromachining processes, such as turning, milling, grinding, and drilling, have been found to be suitable for machining most of the cast and wrought aluminum alloys. On the other hand, nonconventional micromachining processes were approached for the micromachining of aluminum metal matrix composites and alumina ceramics. Some challenges and aspects in the area of micromachining of aluminum alloys that need future considerations are burr formation, tool wear, surface finish, microstructures and properties changes, and process development for advanced and hybrid micromachining.
Electrodeposition of Aluminum in Ionic Liquids
Authors: Wang Qian , Zhang Suojiang , Lu Xingmei , Zhang Xiangping
Published: February 2019

Compared with the industrial Siemens-Galvano-Aluminum (SIGAL) process, electrodeposition of aluminum (Al) in ionic liquids (ILs) has gained more and more attention due to the excellent characteristics of ILs, such as almost non-volatile, wider electrochemical window, higher conductivity, and so on. Therefore, in this article we give a detailed report on the development of this field. In order to enhance the potential of ILs used as electrolytes for Al electrodeposition, this article also reviews the background and historical development of electrodeposition of Al in ILs. Through summarizing, we find that the chloroaluminate ILs with imidazolium as the cations are still the most prospective electrolytes for large-scale application, and moisture sensitivity is the biggest obstacle restricting its development. Therefore, researchers have been looking for stronger water resistant ILs, but the water insensitive ILs are hard to combine with low viscosity and high electrochemical conductivity, leading to little research work done for the industrial application of electrodeposition of Al in ILs. In addition, the existing problems in basic research and application of electrodeposition of Al in ILs are summarized.
Microstructure of Aluminum Alloys: Effect of Hardening Conditions
Authors: Demirören Hülya
Published: February 2019

In the present article, aluminum and its heat treatments were expressed. Also it was investigated that the influence of quenching type after solutizing heat treatment of cast Al-8.88Si-3.38 Cu on the microstructure has been reported. Alloys were prepared by controlled melting and casting. All the alloys were solutionized at 525°C for 4 h followed by water quenching at 65°C for 1, 15, 30, 60, and 90 min, respectively, and aged at 175°C for 4 h. Then they were cooled at room temperature. It was performed SEM–EDX analysis and X-ray analysis. From the analysis, it was determined Al2Cu and Al7FeCu2 phases. It was determined that those phases reinforce the microstructure. As a result, the type of quenching after solution treatment is very important for aluminum alloys.
Fatigue Endurance under Torsion Testing: 6061-T6 and 6063-T5 Aluminum Alloys
Authors: L. Avila Ambriz Jorge , Correa Gómez Erasmo , Verduzco Juárez Julio C. , Dominguez Almaraz Gonzalo M. , Dominguez Aymeric E.
Published: February 2019

This article deals with torsion fatigue tests carried out on the aluminum alloys: AISI 6061-T6 and 6063-T5, under two load ratios: R = −1 and R = 0, both of them at 10 Hz of frequency. The tests were obtained at room temperature (23°C) and with environmental humidity comprised between 35% and 45%. Results reveal a noticeable fatigue endurance reduction on tests with R = 0 against tests at R = −1 for both aluminum alloys. The load ratio was fixed by imposing the initial angle before the testing starting. A new torsion fatigue machine has been developed by two of the authors (under patent consideration before the Mexican Institute of Industrial Property), which has the versatility of torsion tests at different frequencies and load ratios; a general description of this machine is presented in the article. The torsion fatigue life and the fracture surfaces were analyzed for the two aluminum alloys and both torsion fatigue load ratios, leading to drawing up the conclusions related to this research article.
Microstructure Imaging, Precipitation Formation and Mechanical Properties: Al–Li and Al–Mg–Zn Alloys
Authors: Wunderlich Wilfried , Lendvai Janos , Gudladt Hans-Joachim
Published: February 2019

This article describes concepts of three features of microstructure–properties relationship, first the imaging and formation of nano-particles, then their contribution to hardness, and finally hydrogen embrittlement during fatigue. First, we briefly review the imaging modes in transmission electron microscopy (TEM) for nano-sized precipitates. The next issue is the hardening in Aluminum alloys, which is caused by GP-zones or precipitates, formed at the second step of the annealing process. After homogenization, the peak-hardness can be generally achieved by a few hours of annealing between 120°C and 200°C. Hardness measurements and equal-channel axial pressing (ECAP) showed that even at room temperature the driving force for formation of the particles is so strong that already within one hour of annealing after homogenization a remarkable hardening occurs. The third issue, hydrogen embrittlement, is caused by oxidation of pure Al surfaces produced at the crack tip during fatigue under ambient or wet moisture conditions. The cracks propagate preferentially along the precipitation free zone adjacent to grain boundaries, where hydrogen diffusion is fastest.
Quench Factor Analysis
Authors: Simencio Otero Rosa L. , Kavalco Patricia M. , Canale Lauralice C. F. , Totten George E. , Meekisho Lemmy
Published: February 2019

One of the steps of the heat treatment process of age-hardenable aluminum alloys is the quenching process in which the alloy is cooled from the solutionizing temperature. The objective is to quench sufficiently fast to avoid undesirable concentration of alloying elements in the defect and grain boundary structure while at the same time not quenching faster than necessary to minimize residual stresses, which may lead to excessive distortion, or cracking. Various studies have been conducted to predict the relative quench rate sensitivity to yield different properties for age-hardenable alloys. Of these different predictive methods, the one that showed the more realistic results is quench factor analysis (QFA) since it involves a correlation of the cooling curve (time–temperature curve) of the cooling process throughout the quenching cycle for the desired cross-section size of interest with a C-curve (Time–Temperature–Property Curve) for the specific alloy of interest. The QFA numerical procedure has evolved since its original introduction. A review of the basic assumptions of the classical QFA model will be provided here, which will include discussion of the various improvements to the classical model that have been proposed over the intervening years since its introduction.
Uphill Quenching of Aluminum Alloys
Authors: da Silva Mattos Wellington , Totten George Edward , Canale Lauralice de Campos Franceschini
Published: February 2019

This article describes the concept of uphill quenching process applied in the heat treatment of aluminum alloys. Uphill quenching is interesting since residual stress reductions of up to 80% has been reported. In addition, substantial improvements in dimensional stability have been achieved for several types of aluminum parts. Often, uphill quenching is applied after quenching and before aging during the heat treatment of aluminum alloys. The uphill quenching process consists of the immersion of the part in a cryogenic environment, and after homogenization of the temperature, the part is transferred to the hot steam chamber to obtain a temperature gradient that will maintain the mechanical properties gained with this process. The results obtained are lower residual stress and better dimensional stability. The aim of this article is to provide a review of this process and to compare it with conventional heat treatment.
Al-Mg-Si: Microstructural Analysis
Authors: Cabibbo Marcello
Published: February 2019

This article presents two case studies referring to the severe plastic deformation applied to Al-Mg-Si alloys. In a first case study, an Al-Mg-Si alloy in a T6 temper is subjected to equal-channel angular pressing (ECAP), and all the microstructure strengthening contributions to the alloy yield stress are determined through specific modeling and then validated. In a second case study, two Al-Mg-Si alloys, one with Zr addition and a second with Sc-Zr addition, are subjected to ECAP after a T6 temper in an overaged status. In the second case, the role of the Zr- and Sc-Zr-containing nanometer dispersoids is described, and the related strengthening effect is modeled according to the models presented in the first case study.
As-Cast Grain Size of Aluminum Alloys Refined by Al-Ti-B Master Alloys
Authors: Easton Mark , St John David , Arvind Prasad
Published: February 2019

Grain refinement is a critical technology for the successful production of cast parts; whether that be preforms such as extrusion billet or rolling slab, or near net-shape castings. A refined microstructure has many advantages with reduced defects and improved mechanical properties. This article describes the approaches to the prediction of grain size in Al-alloys refined by Al-Ti-B master alloys. Included are empirical approaches based on the generation and analysis of grain size data, the development of analytical equations, and the use of finite element approaches to the prediction of grain sizes. It is clear that researchers have a good ability to predict grain size of Al-alloys grain refined by Al-Ti-B master alloys, although there are still some outstanding challenges, particularly in considering more extreme solidification conditions and poisoning of the master alloys.
The Crystallography of Aluminum and Its Alloys
Authors: Nakashima Philip N.H.
Published: February 2019

This article begins with pure aluminum and a discussion of the form of the crystal structure and different unit cells that can be used to describe it. Measurements of the face-centered cubic lattice parameter and thermal expansion coefficient in pure aluminum are reviewed and parametrizations are given which allow the reader to evaluate them across the full range of temperatures where aluminum is a solid. A new concept called the “vacancy triangle” is introduced and demonstrated as an effective means for determining vacancy concentrations near the melting point of aluminum. The Debye–Waller factor, quantifying the thermal vibration of aluminum atoms in pure aluminum, is reviewed and parametrized over the full range of temperatures where aluminum is a solid. The nature of interatomic bonding and the history of its characterization in pure aluminum are reviewed with the unequivocal conclusion that it is purely tetrahedral in nature. The crystallography of aluminum alloys is then discussed in terms of all of the concepts covered for pure aluminum, using prominent alloy examples. The electron density domain theory of solid-state nucleation and precipitate growth is introduced and discussed as a new means of rationalizing phase transformations in alloys from a crystallographic point of view.
Carbothermic Reduction Methods for Alumina
Authors: Balomenos Efthymios , Gerogiorgis Dimitrios
Published: February 2019

The Hall–Héroult process for the electrolytic reduction of alumina was developed at the end of the 19th century and is still currently the only industrial process for the production of primary aluminum. Today, this process is ranked among the most energy- and CO2intensive industrial processes. Direct carbothermic reduction of alumina has been proposed as an alternative process, which can substantially improve the sustainability of primary aluminum production, leading to energy savings of up to 21% and reduction in greenhouse gas emission of up to 52%, while plant capital costs can be reduced up to 50%. However, processes developed so far suffer from low aluminum yields, primarily due to aluminum carbide and oxycarbide formation and aluminum vaporization phenomena. This article presents a thermodynamic study of the Al–C–O system and a review on the alumina carbothermic processes developed so far.
Electrical Conductivity of Aluminum Alloy A2011
Authors: Bakhtiyarov Sayavur , Overfelt Ruel
Published: February 2019

A rotational, contactless inductive measurement technique has been used to determine the effect of pores and metallic insertions on the electrical resistivity of A2011 aluminum alloy at different temperatures. It is shown that the electrical resistivity increases with the total volume of pores and is also dependent on the pores locations and orientation. Additional energy losses were found on the contact surfaces between sample and insertions.
Polyphase Eutectics of Aluminum Alloys: Effect of Phase Composition
Authors: Warmuzek Malgorzata
Published: February 2019

The polyphase eutectics (α-Al+intermetallic+Si) constituting the final aluminum alloy microstructure were characterized by their phase composition, growth mechanism, and morphology of eutectic crystals. The main groups of eutectic phase constituents were presented with a special attention paid to intermetallic phases. Morphology of different types of polyphase eutectics, among those divorced, was characterized and presented (as microscopic images) on microphotographs. The microstructural effects of stable and metastable phases competition in the stage of nucleation and growth of polyphase eutectics as affected by local cooling rate and liquid alloy composition were described. Some examples of the evolution of the phase composition of eutectics in commercial alloys due to modifications of technological procedures were presented.
High-Speed Computer Tomography: Pressure Die Casting
Authors: Heikel Christian , Ambos Eberhard
Published: February 2019

For many years, molders have been trying to figure out the influence of diverse factors on the quality of die castings during molding. In 2010, the rapid computer tomograph became available for the first time. This system is derived from medical technology and offers new testing methods. The measures, which have been in progress for the past 5 years, were focused to point out the correlation between the major influences of pore expression in pressure die castings. These results are suggestive of the future technological and constructive work. Through continuous improvements in testing methods, the technology finally succeeded to work out major influences on pore expressions in pressure die castings. With these new findings, it is possible, and even proven by example, that through the right choice of process parameters strength-influencing pores can be reduced. In case of not preventing the formation of pores, they could be moved out of the areas, which are strength vulnerable. This is an appropriate concept to reduce the weight of components and therefore the implementation of lightweight constructions in the automotive industry.
Homogeneous Modifier-Treated AlSi10Mg Alloy: Microstructure and Mechanical Properties
Authors: Lipiński Tomasz
Published: February 2019

The microstructure of an unmodified hypoeutectic Al–Si alloy comprises large primary alpha phase and eutectic alpha phase dendrites and eutectic beta phase crystals. The mechanical properties of silumins can be improved through chemical modification. This article discusses the modification of an EN AC-AlSi10Mg hypoeutectic alloy with the use of a modifier made of processed alloys and an Al–Si alloy solidified at the velocity of 373, 473, 573, and 673 K/s. The applied alloys were referred to as homogeneous modifiers. The content of modifiers in the silumin alloy reached 0.3%–1.5% by weight. The alloy was subjected to tensile strength, relative elongation, and hardness tests before and after modification. The alloy was cast into a sand mold. The results of the study indicate that alloy microstructure can be modified and its mechanical properties can be improved by incorporating the proposed homogeneous modifiers into a liquid alloy. Mechanical properties were improved when an Al–Si modifier with higher silicon content than the modified alloy was used and when the cooling rate was increased to 573 K/s. A further increase in the cooling rate of the modifier did not lead to a significant improvement in the mechanical properties.
Wrought Aluminum Alloy: Reinforcement, Alloy Addition, and Deformation Effects on Mechanical Responses
Authors: Adeosun Samson Oluropo , Akpan E. I. , Balogun S. A.
Published: February 2019

This article discusses the effects of various modifications on the properties of aluminum alloys for structural applications. The effect of reinforcing particles on the mechanical properties of wrought 6063 aluminum alloy arising from our previous works is extensively discussed to identify the most promising reinforcing particles. It also discusses the improvement in mechanical properties of 1200 aluminum alloy using silicon carbide particulates. The effect of micro-alloy additions on the mechanical properties is also outlined in this article based on the results from our previous experimental works. Effect of combining heat treatment and deformation on the mechanical properties of wrought aluminum alloys is also presented. Results presented show that particle reinforcement, deformation, and microelemental additions to aluminum alloy result in significant improvement in mechanical properties of the alloys considered. Addition of reinforcing particles of barite, silicon carbide, iron fillings, and electric arc furnace dust are found to impart improved tensile strength to aluminum alloy. The most outstanding finding is that synergy between particle addition, deformation, and heat treatment has a good prospect in the production of improved aluminum alloy materials for automotive applications.
Castings: Ten Rules for Good Castings
Authors: Campbell John
Published: February 2019

The Ten Rules are a checklist of the conditions necessary for the production of successful castings, particularly dealing with the metal quality, with a view to achieving a casting with minimal, preferably zero, faults. The first five Rules specify the conditions to avoid entrainment defects, particularly bifilms and bubbles. The remaining Rules deal with the provision of feeding, avoidance of convection, chemical segregation, and residual stress, and the provision of pickup locations for machining.