bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuropeptide depletion in the amygdala in sudden unexpected death in epilepsy: A postmortem study
Authors: Somani Alyma , Perry Charlotte , Patodia Smriti , Michalak Zuzanna , Ellis Matthew , Sisodiya Sanjay M. , Thom Maria
Published: January 2020

Objective

Sudden unexpected death in epilepsy (SUDEP) is typically unwitnessed but can be preceded by seizures in the period prior to death. Peri‐ictal respiratory dysfunction is a likely mechanism for some SUDEP, and central apnea has been shown following amygdala stimulation. The amygdala is enriched in neuropeptides that modulate neuronal activity and can be transiently depleted following seizures. In a postmortem SUDEP series, we sought to investigate alterations of neuropeptidergic networks in the amygdala, including cases with recent poor seizure control.

Methods

In 15 SUDEP cases, 12 epilepsy controls, and 10 nonepilepsy controls, we quantified the labeling index (LI) for galanin, neuropeptide Y (NPY), and somatostatin (SST) in the lateral, basal, and accessory basal nuclei and periamygdala cortex with whole slide scanning image analysis. Within the SUDEP group, seven had recent generalized seizures with recovery 24 hours prior to death (SUDEP‐R).

Results

Galanin, NPY, and SST LIs were significantly lower in all amygdala regions in SUDEP cases compared to epilepsy controls (P < .05 to P < .0005), and galanin LI was lower in the lateral nucleus compared to nonepilepsy controls (P < .05). There was no difference in the LI in the SUDEP‐R group compared to other SUDEP. Higher LI was noted in epilepsy controls than nonepilepsy controls; this was significant for NPY in lateral and basal nuclei (P < .005 and P < .05).

Significance

A reduction in galanin in the lateral nucleus in SUDEP could represent acute depletion, relevant to postictal amygdala dysfunction. In addition, increased amygdala neuropeptides in epilepsy controls support their seizure‐induced modulation, which is relatively deficient in SUDEP; this could represent a vulnerability factor for amygdala dysfunction in the postictal period.
Human land uses reduce climate connectivity across North America
Authors: Parks Sean A. , Carroll Carlos , Dobrowski Solomon Z. , Allred Brady W.
Published: January 2020

Climate connectivity, the ability of a landscape to promote or hinder the movement of organisms in response to a changing climate, is contingent on multiple factors including the distance organisms need to move to track suitable climate over time (i.e. climate velocity) and the resistance they experience along such routes. An additional consideration which has received less attention is that human land uses increase resistance to movement or alter movement routes and thus influence climate connectivity. Here we evaluate the influence of human land uses on climate connectivity across North America by comparing two climate connectivity scenarios, one considering climate change in isolation and the other considering climate change and human land uses. In doing so, we introduce a novel metric of climate connectivity, ‘human exposure’, that quantifies the cumulative exposure to human activities that organisms may encounter as they shift their ranges in response to climate change. We also delineate potential movement routes and evaluate whether the protected area network supports movement corridors better than non‐protected lands. We found that when incorporating human land uses, climate connectivity decreased; climate velocity increased on average by 0.3 km/year and cumulative climatic resistance increased for ~83% of the continent. Moreover, ~96% of movement routes in North America must contend with human land uses to some degree. In the scenario that evaluated climate change in isolation, we found that protected areas do not support climate corridors at a higher rate than non‐protected lands across North America. However, variability is evident, as many ecoregions contain protected areas that exhibit both more and less representation of climate corridors compared to non‐protected lands. Overall, our study indicates that previous evaluations of climate connectivity underestimate climate change exposure because they do not account for human impacts.
Mapping the spectrum of psychological and behavioural responses to low‐dose CT lung cancer screening offered within a Lung Health Check
Authors: Kummer Sonja , Waller Jo , Ruparel Mamta , Cass Judith , Janes Samuel M. , Quaife Samantha L.
Published: January 2020

Background

Research on the psychological impact of low‐dose computed tomography (LDCT) lung cancer screening has typically been narrow in scope and restricted to the trial setting.

Objective

To explore the range of psychological and behavioural responses to LDCT screening offered as part of a Lung Heath Check (LHC), including lung cancer risk assessment, spirometry testing, a carbon monoxide reading and smoking cessation advice.

Methods

Semi‐structured interviews were carried out with 28 current and former smokers (aged 60‐75), who had undergone LDCT screening as part of a LHC appointment and mostly received an incidental or indeterminate result (n = 23). Framework analysis was used to map the spectrum of responses participants had across the LHC appointment and screening pathway, to their LDCT results and to surveillance.

Results

Interviewees reported a diverse range of both positive and negative psychological responses, beginning at invitation and spanning the entire LHC appointment (including spirometry) and LDCT screening pathway. Similarly, positive behavioural responses extended beyond smoking cessation to include anticipated implications for other cancer prevention and early detection behaviours, such as symptom presentation. Individual differences in responses appeared to be influenced by smoking status and LDCT result, as well as modifiable factors including perceived risk and health status, social support, competing priorities, fatalism and perceived stigma.

Conclusions

The diverse ways in which participants responded to screening, both psychologically and behaviourally, should direct a broader research agenda to ensure all stages of screening delivery and communication are designed to promote well‐being, motivate positive behaviour change and maximize patient benefit.
Use of bibliometric analysis of Greek hospital personnel publications
Authors: Pylarinou Stamatoula , Kapidakis Sarantos
Published: January 2020

In this paper, Stamatoula Pylarinou with her supervisor Prof. Sarantos Kapidakis reports on an analysis of bibliographic data of the publications of Greek hospital personnel, conducted as part of Stamatoula’s doctoral research in the Department of Archive, Library and Museum Sciences at the Ionian University in Corfu, Greece. Using freely available data, they demonstrate the questions posed and the insights gained from the analysis of the scientific publications of personnel of public hospitals in Greece, in particular amid the years of austerity in Greece. With regard to impact on practice, they suggest that these procedures for the processing of medline/PubMed bibliographic data can improve communication among hospital librarians and administration or patients, adding value to their duties and enhancing the information and services they can provide. F.J.
Promotion of wound healing by acetate in murine colonic epithelial cell via c‐Jun N‐terminal kinase activation
Authors: Nakano Takahiro , Uchiyama Kazuhiko , Ushiroda Chihiro , Kashiwagi Saori , Toyokawa Yuki , Mizushima Katsura , Inoue Ken , Dohi Osamu , Okayama Tetsuya , Yoshida Naohisa , Katada Kazuhiro , Kamada Kazuhiro , Handa Osamu , Ishikawa Takeshi , Takagi Tomohisa , Konishi Hideyuki , Naito Yuji , Itoh Yoshito
Published: January 2020

Background and Aim

Mucosal healing is an important clinical goal in patients with inflammatory bowel disease. Recently, short‐chain fatty acids (SCFAs) have been reported to have multifaceted effects to host. However, the effects of SCFAs on wound healing in intestinal epithelial cells are unclear. In the present study, we investigated the effects of acetate, one of the major SCFAs, on the wound healing of murine colonic epithelial cells.

Methods

Young adult mouse colonic epithelial cells were used to determine the effect of acetate using wound healing assay. Mitogen‐activated protein kinase and Rho kinase inhibitor were used to elucidate intracellular signal of wound healing treated with acetate. Meanwhile, Rho activation assays were utilized to measure Rho activation levels. To assess in vivo effects, C57B6 mice with dextran sodium sulfate for 7 days were treated with enema administration of acetate for 7 days. Body weight, disease activity index, colon length, and mucosal break ratio in histology were examined.

Results

Acetate enhanced wound healing and fluorescence intensity of actin stress fiber compared with control. These effects were canceled with pretreatment of c‐Jun N‐terminal kinase (JNK) inhibitor or Rho kinase inhibitor. Furthermore, JNK inhibitor reduced the activation of Rho induced by acetate. In the dextran sodium sulfate‐induced colitis model, the mice with enema treatment of acetate significantly exhibited recovery.

Conclusions

In this study, we demonstrated that acetate promoted murine colonic epithelial cell wound healing via activation of JNK and Rho signaling pathways. These findings suggested that acetate could have applications as a therapeutic agent for patients with intestinal mucosal damage, such as inflammatory bowel disease.
Treatment and outcomes of ureter injuries due to ovariohysterectomy complications in cats and dogs
Authors: Plater B. L. , Lipscomb V. J.
Published: January 2020

Objectives

To describe the presentation, treatment and outcome of unilateral and bilateral ureter injuries resulting from ovariohysterectomy complications in cats and dogs.

Materials and Methods

Retrospective case series of cats and dogs with ureteric injuries resulting from an ovariohysterectomy complication. Patient signalment, history, presenting clinical signs, clinical pathology, imaging, diagnosis, treatment and outcome were obtained from the medical records and telephone contact with the owners.

Results

Fourteen female cats and five female dogs were included. Eleven (58%) exhibited clinical signs immediately after recovery from ovariohysterectomy, six (32%) had a median onset of clinical signs of 3 days (range 1 to 16 days), and two (10%) were referred immediately because of a known complication during surgery. Five of seven animals with bilateral ureter injury presented with anuria. Three animals died or were euthanased without definitive surgery. Surgical repair included ureteroneocystostomy (eight cats, one dog), ureteronephrectomy (four cats, two dogs), subcutaneous ureteral bypass placement (three cats) and ureteral stent (one cat). Of the 16 operated animals, seven (44%) that were discharged from the hospital experienced major complications requiring one or more additional surgeries. Overall outcome was excellent in 13 (68%), good in one (5%), fair in one (5%) and poor in four (22%) animals.

Clinical Significance

A key indicator of a ureteric injury is an animal failing to recover normally or becoming unwell shortly after ovariohysterectomy. Anuria is likely in animals with bilateral ureter injury. Excellent outcomes are possible following surgical treatment.
Short‐term kinetics of rRNA degradation in Escherichia coli upon starvation for carbon, amino acid or phosphate
Authors: Fessler Mathias , Gummesson Bertil , Charbon Godefroid , Svenningsen Sine Lo , Sørensen Michael A.
Published: January 2020

Ribosomes are absolutely essential for growth but are, moreover, energetically costly to produce. Therefore, it is important to adjust the cellular ribosome levels according to the environmental conditions in order to obtain the highest possible growth rate while avoiding energy wastage on excess ribosome biosynthesis. Here we show, by three different methods, that the ribosomal RNA content of Escherichia coli is downregulated within minutes of the removal of an essential nutrient from the growth medium, or after transcription initiation is inhibited. The kinetics of the ribosomal RNA reduction vary depending on which nutrient the cells are starved for. The number of ribosomes per OD unit of cells is roughly halved after 80 min of starvation for isoleucine or phosphate, while the ribosome reduction is less extensive when the cells are starved for glucose. Collectively, the results presented here support the simple model proposed previously, which identifies the inactive ribosomal subunits as the substrates for degradation, since the most substantial rRNA degradation is observed under the starvation conditions that most directly affect the protein synthesis.
A link between mitochondrial gene expression and life stage morphologies in Trypanosoma cruzi
Authors: Ramirez‐Barrios Roger , Susa Emily K. , Smoniewski Clara M. , Faacks Sean P. , Liggett Charles K. , Zimmer Sara L.
Published: January 2020

The protozoan Trypanosoma cruzi has a complicated dual‐host life cycle, and starvation can trigger transition from the replicating insect stage to the mammalian‐infectious nonreplicating insect stage (epimastigote to trypomastigote differentiation). Abundance of some mature RNAs derived from its mitochondrial genome increase during culture starvation of T. cruzi for unknown reasons. Here, we examine T. cruzi mitochondrial gene expression in the mammalian intracellular replicating life stage (amastigote), and uncover implications of starvation‐induced changes in gene expression. Mitochondrial RNA levels in general were found to be lowest in actively replicating amastigotes. We discovered that mitochondrial respiration decreases during starvation in insect stage cells, despite the previously observed increases in mitochondrial mRNAs encoding electron transport chain (ETC) components. Surprisingly, T. cruzi epimastigotes in replete medium grow at normal rates when we genetically compromised their ability to perform insertion/deletion editing and thereby generate mature forms of some mitochondrial mRNAs. However, these cells, when starved, were impeded in the epimastigote to trypomastigote transition. Further, they experience a short‐flagella phenotype that may also be linked to differentiation. We hypothesize a scenario where levels of mature RNA species or editing in the single T. cruzi mitochondrion are linked to differentiation by a yet‐unknown signaling mechanism.
The constitution of space in intensive care: Power, knowledge and the othering of people experiencing mental illness
Authors: Corfee Flora , Cox Leonie , Windsor Carol
Published: January 2020

A sociological conceptualisation of space moves beyond the material to the relational, to consider space as a social process. This paper draws on research that explored the reproduction of legitimated knowledge and power structures in intensive care units during encounters, between patients, who were experiencing mental illness, and their nurses. Semi‐structured telephone interviews with 17 intensive care nurses from eight Australian intensive care units were conducted in 2017. Data were analysed through iterative cycling between participants' responses, the literature and the theoretical framework. The material and relational aspects of space in this context constitute a dynamic process that is concerned with the reproduction of everyday life, the preservation of the biomedical authority of intensive care, and the social othering of people experiencing mental illness. The work of theorists such as Löw, Harvey and Foucault underpins the exploration of space as a multi‐dimensional, malleable social process that both produces and is the product of social interaction and the social world. In this paper, we argue that the performative work of knowledge and power production and reproduction, considered here in relation to intensive care spaces, enables ongoing othering and disenfranchisement of people experiencing mental illness.
Comparison of Total Hip Arthroplasty after Two Types of Failed Hip Preserving Procedures with Primary Total Hip Arthroplasty
Authors: Zuo Wei , Ma Jin‐hui , Cui Wei , Guo Wan‐shou , Sun Wei
Published: January 2020

Objective

Porous tantalum implantation (PTI) and bone impaction grafting (BIG) through a window at the femoral head neck junction are known as two types of joint‐preserving procedures. They provide an alternative option in the treatment of osteonecrosis of the femoral head by providing strong structural support to the subchondral plate. However, when earlier joint‐preserving treatments fail, conversion to a total hip arthroplasty seems to be the final treatment of choice. This emphasizes the importance of joint‐preserving procedures that do not hinder the clinical results of a subsequent total hip arthroplasty. The results of conversion total hip arthroplasty after failed PTI and BIG are still controversial. The purpose of this study was to compare the clinical and radiological outcomes of total hip arthroplasty after failed PTI or BIG surgery with primary total hip arthroplasty.

Methods

Patients at our institution between 2010 and 2014 who underwent total hip arthroplasty after failed PTI or BIG surgery compared to primary total hip arthroplasty were retrospectively reviewed. A total of 27 patients (30 hips) who underwent total hip arthroplasty after failed PTI surgery (group I) were matched according to age, gender and BMI index with 28 patients (30 hips) who underwent total hip arthroplasty after failed BIG surgery (group II) and 30 patients (30 hips) who underwent primary total hip arthroplasty (group III). The clinical results included preoperative and postoperative Harris Hip score, surgery duration, blood loss volume and clinical complications. Radiological follow‐up results included abduction angle and anteversion angle of the acetabular cup, periprosthetic osteolysis, and prosthesis subsidence.

Results

There was no significant difference in the preoperative and postoperative Harris Hip score among the three groups at the latest follow‐up (P = 0.247). The surgery duration was longer and intra‐operative blood loss volume was higher in group I than in group II and group III (P < 0.05, respectively). There was no difference in surgery duration and blood loss volume between group II and group III (P > 0.05). There was no significant difference in radiological follow‐up results among the three groups (P > 0.05). Varying degrees of residual tantalum debris were seen on postoperative radiographs of all group I patients. There was no difference in the incidence of complications among the three groups (P > 0.05).

Conclusions

PTI group had higher blood loss volume and surgery duration than BIG group and primary total hip arthroplasty group. BIG group had no significant differences with primary total hip arthroplasty group in clinical and radiological follow‐up results. There were no significant differences between the three groups in the Harris Hip score and radiological follow‐up results.
Knowledge, reasoning, and deliberation
Authors: Kim Brian
Published: January 2020

Epistemologists have become increasingly interested in the practical role of knowledge. One prominent principle, which I call PREMISE, states that if you know that p, then you are justified in using p as a premise in your reasoning. In response, a number of critics have proposed a variety of counter‐examples. In order to evaluate these problem cases, we need to consider the broader context in which this principle is situated by specifying in greater detail the types of activity that the principle governs. I argue that if PREMISE is interpreted as governing deductive reasoning, then the examples lose their force. In addition, I consider the cases, discussed by Keith DeRose, where the subject is in more than one practical context at the same time. In order to account for these latter cases, we need to further specify the scope of PREMISE. I distinguish two ways of understanding PREMISE, as a knowledge‐action principle and as a knowledge‐deliberation principle. I conclude by arguing for the knowledge‐deliberation version of the principle and by exploring what this principle says about the practical role of knowledge.
Race Differences in Motivations for Joining Unions: The Role of Prosocial Beliefs
Authors: Gumber Clayton , Padavic Irene
Published: January 2020

Objective

This article investigates whether a prosocial orientation—which stresses unions’ concern for all working people—might differentially influence whites’ and African Americans’ decisions to join unions.

Methods

Logistic regression using data from the 2005 AFL‐CIO Union Message Survey.

Results

African Americans’ odds of voting “yes” in a hypothetical union election are nearly two times greater than whites’ odds, and prosocial beliefs partially mediate this effect.

Conclusion

A model of unionism that seeks political goals beyond narrow workplace ones (i.e., that capitalizes on the prosocial orientation documented here) may increase unions’ success in attracting African‐American members, thereby improving African Americans' labor market experience and revitalizing the labor movement.
Use of pre‐ART laboratory screening to identify renal, hepatic and haematological abnormalities in Côte d'Ivoire
Authors: Minchella P. A. , Adjé‐Touré C. , Zhang G. , Tehe A. , Hedje J. , Rottinghaus E. R. , Natacha K. , Diallo K. , Ouedraogo G. L. , Nkengasong J. N.
Published: January 2020

Background

High demand for HIV‐services and extensive clinical guidelines force health systems in low‐resource settings to dedicate resources to service delivery at the expense of other priorities. Simplifying services may reduce the burden on health systems and pre‐antiretroviral therapy (ART) laboratory screening is among the services under consideration for simplification.

Methods

We assessed the frequencies of conditions linked to ART toxicities among 34,994 adult, ART‐naïve patients with specimens referred to the RETRO‐CI laboratory in Abidjan, Côte d’Ivoire between 1998 and 2017. Screening included tests for serum creatinine, alanine aminotransferase (ALT) and haemoglobin (Hb) to identify renal dysfunction (estimated glomerular filtration rate < 50 mL/min), hepatic abnormalities (ALT > 5× upper limit of normal) and severe anaemia (Hb < 6.5 g/dL), respectively. We considered screening results across four eras and identified factors associated with the conditions in question.

Results

The prevalence of renal dysfunction, hepatic abnormalities and severe anaemia were largely unchanged over time and just 8.4% of patients had any of the three conditions. Key factors associated with renal dysfunction and severe anaemia were age > 50 years (adjusted odds ratio (aOR): 2.53; 95% confidence interval (CI): 2.19–2.92; P < 0.001) and CD4 < 100 cells/µl (aOR: 2.57; 95% CI: 2.30–2.88; P < 0.001).

Conclusion

The relative infrequency of conditions linked to toxicity in Côte d’Ivoire supports the notion that simplification of pre‐ART laboratory screening may be undertaken with limited negative impact on identification of adverse events. Targeted screening may be a feasible strategy to balance detection of conditions associated with ART toxicities with simplification of services.
The Reflection of the Ethnic Ethos in the Shaping of Mizrahi Female Characters, in the Light of the Literary Criticism of Yaakov Churgin’s Books – Sipurim (1928), Alumot (1957), and Yalkut Sipurim (1981)
Authors: Dori Nitsa
Published: January 2020

This article suggests taking a close look at the stories of Eretz-Israel author Yaakov Churgin (1899 – 1990) as a hybrid system of identities, that is ambivalent and unclassified, that can also fit stories about Jews of Ashkenazic origin as they were portrayed in the stories of the Jewish shtetls by authors such as Shalom Aleichem, Dvora Baron, Isaac Bashevis Singer, and Shay Agnon, while identifying the similarity between secular or enlightened Orientalism’s attitude to traditional or religious society, and Ashkenazic Orientalism’s attitude to the Mizrahi Jews in Eretz-Israel. The article will also suggest a new diachronic examination of the literary criticism regarding Churgin’s writing in its ethnic context, that will review the primary criticism over the years and address the characteristics of this criticism in light of the changes over the years.
Matching of orbital integrals (transfer) and Roche Hecke algebra isomorphisms
Authors: Lemaire Bertrand , Mishra Manish
Published: January 2020

Let $F$ be a non-Archimedean local field, $G$ a connected reductive group defined and split over $F$, and $T$ a maximal $F$-split torus in $G$. Let $\unicode[STIX]{x1D712}_{0}$ be a depth-zero character of the maximal compact subgroup $T$ of $T(F)$. This gives by inflation a character $\unicode[STIX]{x1D70C}$ of an Iwahori subgroup $\unicode[STIX]{x2110}\subset T$ of $G(F)$. From Roche [Types and Hecke algebras for principal series representations of split reductive$p$-adic groups, Ann. Sci. Éc. Norm. Supér. (4) 31 (1998), 361–413], $\unicode[STIX]{x1D712}_{0}$ defines a reductive $F$-split group $\widetilde{G}^{\prime }$ whose connected component $G^{\prime }$ is an endoscopic group of $G$, and there is an isomorphism of $\mathbb{C}$-algebras $\unicode[STIX]{x210B}(G(F),\unicode[STIX]{x1D70C})\rightarrow \unicode[STIX]{x210B}(\widetilde{G}^{\prime }(F),1_{\unicode[STIX]{x2110}^{\prime }})$ where $\unicode[STIX]{x210B}(G(F),\unicode[STIX]{x1D70C})$ is the Hecke algebra of compactly supported $\unicode[STIX]{x1D70C}^{-1}$-spherical functions on $G(F)$ and $\unicode[STIX]{x2110}^{\prime }$ is an Iwahori subgroup of $G^{\prime }(F)$. This isomorphism gives by restriction an injective morphism $\unicode[STIX]{x1D701}:Z(G(F),\unicode[STIX]{x1D70C})\rightarrow Z(G^{\prime }(F),1_{\unicode[STIX]{x2110}^{\prime }})$ between the centers of the Hecke algebras. We prove here that a certain linear combination of morphisms analogous to $\unicode[STIX]{x1D701}$ realizes the transfer (matching of strongly $G$-regular semi-simple orbital integrals). If $\operatorname{char}(F)=p>0$, our result is unconditional only if $p$ is large enough.
On the Geometry of Stiffness and Compliance Under Concatenation
Authors: Kim Charles J.
Published: January 2020

Eigentwists and eigenwrenches capture the stationary stiffness behavior of compliant mechanisms and can be related to a mechanism’s primary kinematic behavior. The nature of concatenation of multiple mechanism building blocks is not well understood. In this paper, we consider the mechanics of concatenation and develop design rules that capture the geometric nature of concatenation in terms of eigenwrenches and eigentwists. The rules are illustrated through mechanisms from the literature and an example design problem. The design rules have potential to provide intelligent guidance for systematic building block synthesis of compliant mechanisms.
Topology Optimization of Rigid-Body Systems Considering Collision Avoidance
Authors: Stöckli Fritz , Shea Kristina
Published: January 2020

Passive dynamic mechanisms can perform simple robotic tasks without requiring actuators and control. In previous research, a computational design method was introduced that integrates dynamic simulation to evaluate and evolve configurations of such mechanisms. It was shown to find multiple solutions of passive dynamic brachiating robots (Stöckli and Shea, 2017, “Automated Synthesis of Passive Dynamic Brachiating Robots Using a Simulation-Driven Graph Grammar Method,” J. Mech. Des. 139(9), p. 092301). However, these solutions are limited, since bodies are modeled only by their inertia properties and thus lack a shape embodiment. This paper presents a method to generate rigid-body topologies based on given inertia properties. The rule-based topology optimization method presented guarantees that the topology is manifold, meaning that it has no disconnected parts, while still connecting all joints that need to be part of the body. Furthermore, collisions with the environment, as well as with other bodies, during their predefined motion trajectories are avoided. A collision matrix enables efficient collision detection as well as the calculation of the swept area of one body in the design space of another body by only one matrix–vector multiplication. The presented collision avoidance method proves to be computationally efficient and can be adopted for other topology optimization problems. The method is shown to solve different tasks, including a reference problem as well as passive dynamic brachiating mechanisms. Combining the presented methods with the simulation-driven method from Stöckli and Shea (2017, “Automated Synthesis of Passive Dynamic Brachiating Robots Using a Simulation-Driven Graph Grammar Method,” J. Mech. Des. 139(9), p. 092301), the computational design-to-fabrication of passive dynamic systems is now possible and solutions are provided as STL files ready to be 3D-printed directly.
Finite Element Method for Fluid Flow in 3D Domains Containing Moving Interfaces
Authors: Mazumder A. K. M. Monayem H.
Published: January 2020

This study presented a three-dimensional (3D) finite element method (FEM) for the numerical analysis of fluid flow in domains containing moving interfaces. This method falls into the general category of Arbitrary Lagrangian Eulerian (ALE) method; based on a fixed mesh that is locally adapted at the moving interfaces and reverts to its original shape once the moving interfaces go over the elements. The 3D domain occupied by the fluid at any time in the simulation is used as the reference domain and is discretized using a mesh of hexahedral tri-linear isoparametric finite elements. The moving interfaces are defined by sets of marker points so that the global mesh is independent of interface movement and eliminates the possibility of mesh entanglement. The mesh never becomes unsuitable due to its continuous deformation, thus eliminating the need for repeated re-meshing and interpolation. A validation is presented via a problem with an analytical solution for the 3D flow between two planes separating at a prescribed speed that shows second order accuracy. The model’s capabilities are illustrated through application to laminar incompressible flows in different geometrical settings that show the flexibility of the technique.
Analytical and Numerical Modelling of Sheet Plate Cold Expanded Hole Subjected to Reverse Yielding
Authors: Bouzid Abdel-Hakim , Touahri Hacène
Published: January 2020

Predicting and mitigating the effect of expansion induced by cold working on damage fatigue accumulation and life assessment of aluminum alloy is a common process in the aeronautics industry, especially to extend the fatigue lifetime of their structures. This process aims at generating residual stresses and increases thereby the strength of hollow parts including aluminum alloy plate holes that are employed in manufacturing the airplane fuselage.

An analytical model to predict the residual stresses induced during the expansion process due to the cold strain hardening is developed. The proposed model is based on an elasto-plastic behavior, with a power law material behaviour and relies on the theory of autofrettaged thick wall cylinders in plane strain state to which reverse yielding is incorporated. The application of Hencky theory of plastic deformation is used in the analytical calculations of the stresses and strains. Finite-element numerical simulation is used to validate the developed analytical model by comparison of the radial, Hoop, longitudinal and equivalent stresses for both the loading and unloading phases. The obtained results show clearly that the level of residual stresses depends mainly on the interference and strain hardening while reverse yielding reduce the stresses near the hole.
Nonlinear Design of a Passive Vibration Isolator: Influence of Multi-Axial Stiffness
Authors: Kaul Sudhir
Published: January 2020

Passive vibration isolators are widely used in multiple engineering applications to reduce resonance peaks or to mitigate transmissibility in the presence of internal or external sources of dynamic excitation. The design of a linear passive isolator involves multiple trade-offs. In the literature, different design configurations with nonlinearities have been investigated to limit some of these trade-offs. These include designs with quasi-zero stiffness (QZS) or high-static-low-dynamic stiffness (HSLDS) characteristics. This study investigates three viscoelastic models that incorporate stiffness nonlinearity along the non-isolating axes in order to exhibit more control over the dynamic response of the isolated system and possibly mitigate some of the design trade-offs. The dynamic response of these three models is compared to an existing HSLDS model in the literature. The three models investigated in this study are as follows: Kelvin-Voigt (or Voigt), Zener, and Generalized Maxwell (or Maxwell Ladder). These three models have been commonly used in the literature for vibration analysis of passive isolators. Two methods have been used for analysis, namely the Harmonic Balance Method (HBM) and explicit numerical integration. Test results from a previous study have been used for model characterization of all the models. It is observed that the modified Kelvin-Voigt model is analogous to the HSLDS model from the literature. For the isolator parameters used in this study, it is observed that the Kelvin-Voigt model with stiffness nonlinearity is able to exhibit characteristics similar to the HSLDS design, this includes the jump phenomenon as well as the hardening behavior. In general, all three models demonstrate that stiffness nonlinearity results in a reduction in peak transmissibility as well as an enhancement of the isolation bandwidth. The findings of this study could be useful in the design of passive isolation systems for products with significantly different multi-axial requirements with various design constraints.
Near Critical Carbon Dioxide Characteristics of Heat Transfer Processes in Microchannels
Authors: Parahovnik Anatoly , Asadzadeh Mostafa , Peles Yoav
Published: January 2020

Convective heat transfer of CO2 flows near the critical condition in a 300 μm hydraulic diameter microchannel was visualized and measured. Flow patterns of the gas, liquid, and supercritical phases are presented and discussed. An experimental rig and a microfluidic device were designed and constructed to enable precise control and measurements of temperature, pressure, and mass flux. Heaters and resistive temperature detectors (RTDs) were formed on the microchannel wall to provide heating power and to measure local surface temperature. Flow patterns for the near-critical condition of CO2 were visualized, and local heat transfer coefficient (HTC) of 4.5, 6.1, and 150 kW/m2K were measured, for gas supercritical and liquid cases, respectively. It was observed that there is a distinct difference in flow and heat transfer patterns of different phases near the critical point, which leads to the deviation of the HTC. Also, CO2 presents high HTC coefficients for supercritical and boiling conditions that make it a viable option as thermal fluid for different micro scale applications.
Ultrasonic Casting of Off-Eutectic Tin Bismuth Solder Alloy for Mechanical Property Testing
Authors: Smith Laura , Jennings Jeff
Published: January 2020

Knowledge of solder mechanical properties is essential when designing electronic assemblies for use in harsh environments like those that exist in automotive or aerospace applications. However, information on solder mechanical properties is limited because fabricating material samples in a form factor used for typical mechanical testing is difficult. Conventional casting processes are prone to void formation and dross inclusion which can degrade the quality of test results acquired and often produce high degrees of variability.

The current work describes in detail a novel casting process which seeks to address these solder sample fabrication issues. The non-conventional process applies ultrasonic excitation to eliminate voiding by breaking up dross inclusions and other voids, so none can form within the melt upon solidification. Cast ingots are machined then undergo non-destructive screening to ensure material consistency within the regions critical to producing good test results prior to being subjected to destructive mechanical testing. This ultrasonic casting process is applied to the testing of an off-eutectic Tin-Bismuth solder alloy and its ambient tensile and compressive stress versus strain properties are evaluated. The improvement in result repeatability for the various tested properties due to the ultrasonic casting are assessed and sample size considerations discussed.
Borehole Temperature Modelling in High Temperature Drilling Environment Based on Heat Transfer Laws
Authors: Chodankar Abhijeet D. , Lin Cheng-Xian
Published: January 2020

High temperature drilling environment has a drastic effect on drilling fluids, wellbore stability, and drilling system components. It has been observed that drilling fluids displace conventional halide based fluids in High Pressure and High Temperature (HPHT) wells leading to corrosion and environmental hazards, while wellbore strengthens further as a result of an increase in fracture initiation pressure in high temperature environment. However, it seriously damages the downhole tools like sensors, elastomer dynamic seals, lithium batteries, electronic component and boards leading to increases in cost and non-productive time. The main objective of this paper is to present an analytical borehole temperature model based on classical heat transfer laws in a high temperature drilling environment. The borehole is modelled using two approaches: composite wall and concentric cylinders. The composite wall and concentric cylinder approaches consist layers of geological formations, drilling fluids outside the drill string, drill string, and drilling fluid inside the drill string. Temperature, heat transfer coefficient, and heat transfer variations along the borehole layers are determined using the derived analytical solutions and tested for different drilling fluid types, air drilling environment, and different drill string materials. The results of composite wall and concentric cylinder models are obtained by using the input field temperatures data in the geological formation and inner annulus of drill pipe to determine the borehole temperature profile in HPHT wells. Therefore, a thorough borehole heat transfer analysis will help in wellbore stability, drilling fluid selection, corrosion control, and optimal placement and material selection of drilling components in HPHT drilling environments.
Using a Heat Pump Experiment With Automated Data Acquisition to Augment Hands-On Learning
Authors: Anderson Kevin R.
Published: January 2020

This paper presents the results of using laboratory facilities in conjunction with computer aided data acquisition in order to enhance the teaching and learning experiences of the air conditioning and measurements/instrumentation courses in an engineering program. The paper discusses the use of educational technology in the form of a laboratory experiment developed for support of Science Technology Engineering and Math (STEM) education in an engineering curriculum. The experimental apparatus discussed in the paper is a heat pump demonstration unit with LabView data collection and visualization software. The use of modern technology in the classroom is illustrated in this paper by using a heat pump demonstration unit to illustrate the physical principles of air conditioning and heating. Data collection and acquisition/instrumentation, data reduction curriculum is addressed by using an automated data collection system to gather data for the heating and cooling processes. The main objectives of the study were to i) expose STEM students to LabView based data collection, ii) enhance the curriculum of air conditioning and measurements science by using hands-on facilities, iii) develop technical report writing and data reduction skill sets. The experiment is conducted in small teams of 3 to 4 students in order to make the experiential learning a more intimate process. The heat pump hardware is used to illustrate real world working system. The experiment is composed of a compressor, an evaporator, a condenser and throttling valve. The unit allows for operation as both a heat pump and a refrigeration unit. Thus illustrating the concept of Coefficient of Performance (COP) and Energy Efficiency Ratio (ERR) for both the heat pump and the refrigeration mode are enabled. The unit works on R134A and water as the working fluids. The unit is instrumented with a control thermostat allowing the set-point of the device to be changed. Thermocouples, pressure transducers and flow rate meters are used to collect live data which is fed to the LabView based data-acquisition platform. By using such equipment in the teaching of the Air Conditioning curriculum, it allows the students
Mechanical Characterization of Valve Compression Packing at High Temperature
Authors: Legault Xavier , Bouzid Abdel-Hakim , Aweimer Ali Salah Omar
Published: January 2020

Packed stuffing boxes are sealing devices used in valves, compressors and pumps. The compression packing is the most critical element of this assembly. Packing rings are compressed axially to produce lateral contact pressures large enough to confine the processed fluid within the pressurized valve and avoids leakage to the outer boundary. Although popular, this old method of sealing has seen very limited analytical and numerical development. There is no standard design procedure for engineers to follow, and the existing standard test procedures are limited to qualification and quality control tests such as API622, 624, ISO-15848 1 and 2. As a result, structural integrity and leak tightness are rarely verified, and consequently 60 % of pressurized equipment requiring fugitive emissions compliance are valves that use this type of sealing device.

The mechanical properties of compression packing materials are the main factors affecting fluid tightness at room and high temperatures and yet there is little or no data available either in manufacturer’s catalogues or in the literature. Packed stuffing box research is scant and focuses mostly on the distribution of the contact pressure between the stem and packing at room temperature without considering packing mechanical properties such as rigidity, thermal expansion, creep and aging. It is proposed, in this project, to measure the mechanical properties such as pressure transmission ratio, short-term creep deformation and thermal expansion coefficient of two packing materials at high temperature. This initiative will serve as a basis to launch a North American testing program to develop ASTM-like testing procedures for compression packing at high temperature.
Assortment of Hydroforming Fluid for Extreme Pressure and Anti Wear Properties
Authors: Rudraksha S. P. , Gawande S. H.
Published: January 2020

Lubricants play vital role in tube hydroforming (THF) process to reduce friction between tool and die wall interface which helps to enhance the quality of finished product. The process parameters and quality of components is influence by the friction between the tube and inner surface of the die. Excellent lubricant reduces the problem of wrinkling, buckling and premature failure of the component. Extreme pressure, Anti-wear, and frictional properties of fluid influence the performance of tube hydroforming process. In this paper EP (extreme pressure), anti-wear and friction properties of hydroforming lubricating oils as Enklo68, Enklo46, Enklo32 and Enklo100 are investigated. Test method as per ASTM standards is used for the measurement of EP and wear preventive properties of hydroforming fluids by using Ball Tester TR – 30L under atmospheric pressure of lubricating oil at 392 N load and 75°C temperature with constant speed of 1770 rpm. From experimental investigations it is observed that as Enklo68 is more suitable hydroforming fluid as compared to Enklo46, Enklo32 and Enklo100 as its observed coefficient of friction (i.e. 0.10581) is very less.
Numerical and Experimental Analysis of Twisted Tape Insert in Circular Tube
Authors: Chandratre V. S. , Keste A. A. , Sane N. K.
Published: January 2020

Energy is a major area of concern for many industrial and engineering applications. For the development of energy efficient heat exchangers, heat transfer enhancement by passive inserts have growing research potential. The present study gives the numerical and experimental analysis of twisted tape insert in a circular tube for the range of Reynolds number between 5000 to 15000 with heat flux variation from 500W/m2 to 1.5 kW/m2 with air as working medium. A circular tube of 52.5 mm internal diameter, 60 mm outer diameter and 1000 mm length is used as test section with uniform heat flux. Twisted tape used is of Aluminum material having a pitch of 100 mm. Outside surface temperatures are measured at different locations on test section. Two ‘T’ type thermocouples are used to measure air temperature at inlet and outlet of test section. From numerical and experimental analysis it is observed that the Nusselt number increases for twisted tape as compared to smooth bare tube by 2.2–3.1 times. Again the Nusselt numbers obtained for smooth tube is compared with Dittus-Boelter and Gnielinski correlation and it is observed that the error is within acceptable limit of 10% variation. An error of 10% variation is observed in friction factor obtained by experimental analysis and Blasius and Petukov correlations.
Explicit Evaluation of Design Readiness for Student Refinement of Conceptual Design
Authors: Iino Kenji , Nakao Masayuki
Published: January 2020

Students at three graduate schools of mechanical engineering and adult groups in Japan have been taking conceptual design courses the authors teach. Among the three graduate schools, the 24 hour course, at the University of Tokyo, spread over 13 classes during 4 months, takes the students all the way from identifying their design goals, generating ideas, refining their designs, to building prototypes. The adult course students also spend long hours of building prototypes. Despite strong encouragement by the instructors for detail design, the students often leave their design concepts at rough stages without refining their ideas to the detail level needed for prototype building. Building a prototype from a design concept that is not fully expanded often results in efforts that lead to failure and retrial. Such back and forth between concepts and physical trial is unavoidable in design, however, if possible they better be kept at the minimum. The instructors, in their efforts to better motivate students to refine the designs, developed a metric “Level of Readiness (LOR) index” for evaluating how refined a design is. Students are better motivated to reach higher scores and this index that evaluate the quality of their designs, in terms of how detail they are, in numbers serves as a better incentive for the students than words from the instructors.