bluuebunny/crossref_metadata_2025 huggingface dataset:
How does emersion time affect embryos of coastal marine invertebrate species? Biochemical responses of three porcelain crabs from the Southeastern Pacific
Authors: Viña‐Trillos Natalia , Guzmán‐Rivas Fabián , Urzúa Ángel
Published: August 2021

Porcelain crabs that inhabit contrasting environments along the Southeastern Pacific coast have developed physiological adaptive responses to the harsh environmental conditions. However, it is not yet known if these responses are already present in early life stages, in embryos, for example, which are more vulnerable to environmental fluctuations than adults. In this study, we subjected ovigerous female crabs of three crab species (Allopetrolisthes punctatus,Petrolisthes laevigatus, andPetrolisthes violaceus) to different periods of emersion (0, 1, 3, and 5 hr) to measure the weight and biochemical parameters (i.e., glucose and lactate) in their embryos after a period of stress induction through emersion. The results indicate that after five hours of emersion,P. laevigatus' embryos had the highest dry weight. This same trend was observed in the embryos ofP. violaceus.Allopetrolisthes punctatus' embryos had the lowest weight. The embryos' glucose content inP. laevigatusandP. violaceuswas consumed during the emersion time, while in embryos ofA. punctatusit remained relatively constant. The highest glucose content was reported inP. laevigatus, followed byP. violaceusandA. punctatus. The lactate content showed an opposite trend and was gradually accumulated with increasing emersion time.Petrolisthes laevigatushad the highest lactate content. This study reveals that the early ontogeny of these porcelain crabs is well adapted to long periods of emersion, showing biochemical adaptive responses linked to aerobic metabolism. These adaptations could reflect a distinctive physiological trait, explaining why porcelain crabs are able to survive in contrasting conditions.
Responses of pea plants to multiple antagonists are mediated by order of attack and phytohormone crosstalk
Authors: Basu Saumik , Clark Robert E. , Bera Sayanta , Casteel Clare L. , Crowder David W.
Published: August 2021

Plants are often attacked by multiple antagonists and traits of the attacking organisms and their order of arrival onto hosts may affect plant defences. However, few studies have assessed how multiple antagonists, and varying attack order, affect plant defence or nutrition. To address this, we assessed defensive and nutritional responses of Pisum sativum plants after attack by a vector herbivore (Acrythosiphon pisum), a nonvector herbivore (Sitona lineatus), and a pathogen (Pea enation mosaic virus, PEMV). We show viruliferous A. pisum induced several antipathogen plant defence signals, but these defences were inhibited by S. lineatus feeding on peas infected with PEMV. In contrast, S. lineatus feeding induced antiherbivore defence signals, and these plant defences were enhanced by PEMV. Sitona lineatus also increased abundance of plant amino acids, but only when they attacked after viruliferous A. pisum. Our results suggest that diverse communities of biotic antagonists alter defence and nutritional traits of plants through complex pathways that depend on the identity of attackers and their order of arrival onto hosts. Moreover, we show interactions among a group of biotic stressors can vary along a spectrum from antagonism to enhancement/synergism based on the identity and order of attackers, and these interactions are mediated by a multitude of phytohormone pathways.
Disagreement unhinged, constitutivism style
Authors: Coliva Annalisa , Palmira Michele
Published: August 2021

Hinge epistemology has to dispel the worry that disagreeing over hinges is rationally inert. Building on a companion piece (Coliva and Palmira 2020), this paper offers a constitutivist solution to the problem of rational inertia by maintaining that a Humean sceptic and a hinge epistemologist disagree over the correct explication of the concept of epistemic rationality. The paper explores the implications of such a solution. First, it clarifies in what sense a disagreement over hinges would be a conceptual disagreement. Secondly, it uses considerations about the (alleged) rational inertia of hinge disagreement to offer a test whereby to demarcate genuine hinges from merely entrenched beliefs. Thirdly, it offers a response to the challenge of explaining why we have reason to engage in the epistemic practices that hinges are constitutive of in the first place. Fourthly, it argues that the constitutivist approach to hinge disagreement does not result in a relativist view.
Hue discrimination in jewellery appraisers exceeds normal performance
Authors: Lovell Julie A , Rabin Jeff C
Published: August 2021

Purpose

The FM‐100 Hue test is used for vocational purposes where hue discrimination is of the upmost importance, such as in jewellery appraisals where small errors in hue discrimination can lead to significant differences in gemstone valuation. The purpose of this study was to determine if the cone contrast test (CCT) could predict performance on the FM‐100 Hue, providing a potential alternative test for screening of jewellery appraisers.

Methods

Members of the National Association of Jewelry Appraisers (NAJA; n = 18, ages 34 to 76 years) requiring colour vision certification with the FM‐100 Hue were invited to participate in a study to assess performance on the Ishihara test, FM‐100 Hue, Lanthony Desaturated D‐15 and the CCT. The FM‐100 Hue test was administered to award or renew NAJA certification, while the CCT was included as a possible alternative certification test.

Results

Average CCT M and S cone scores were predictive of FM‐100 Hue total error score (TES: F1,16 = 7.77, p < 0.02; r2 = 0.33). The regression equation indicates that a CCT score of <60 is 3SD below the mean TES in our cohort of jewellery appraisers. Seventeen of 18 jewellery appraisers had FM‐100 Hue TES scores significantly below the lower limit for age‐matched normal values, indicating exceptional performance (p < 0.001).

Conclusions

Results indicate the CCT may be an effective substitute for the FM‐100 Hue to provide certification of jewellery appraisers, but the small sample size warrants additional comparative validation to support sole utilisation of the CCT. It is of interest that this sample of jewellery appraisers showed lower (i.e., better) than normal TES scores despite mitigating senescence factors. It is conceivable that the enhanced jewellery appraisers' hue discrimination reflects perceptual learning, wherein reward‐based repetition on specific tasks can improve performance, even in adulthood beyond critical periods.
Usability of transparency portals: Examination of perceptions of journalists as information seekers
Authors: Crepaz Michele , Kneafsey Liam
Published: August 2021

Transparency in public institutions is relevant only in so far as the disclosed information is useful for the stakeholders who access it. Hence, we ask: what do users do with the information they obtain through transparency laws? Despite the growing interest in transparency research, the ways transparency portals are used to gather information remain strikingly understudied. We study the use of proactively and reactively disclosed information under four different transparency laws. Data are collected in the Republic of Ireland through a survey of what is generally considered to be the main category of users, benefiters, and guardians of transparency, namely journalists. This is one of the first surveys of the media's use of resources intended to ensure greater transparency in politics and offers a standard approach to the study of open government as a means to improve democratic governance.
Widespread and interrelated gray matter reductions in child sexual offenders with and without pedophilia: Evidence from a multivariate structural MRI study
Authors: Klöckner Mona S. , Jordan Kirsten , Kiehl Kent A. , Nyalakanti Prashanth K. , Harenski Carla L. , Müller Jürgen L.
Published: August 2021

Aim

To further investigate the neuroanatomical correlates of child sexual offending and disentangle them from the neural correlates of pedophilia, using a multivariate analytical approach in order to minimize loss of statistical power.

Methods

This study presents structural MRI data on gray matter in an incarcerated, male population of 22 pedophilic and 21 non‐pedophilic child sexual offenders, and 20 violent non‐sexual offender controls, based on a multivariate whole‐brain approach using source‐based morphometry.

Results

We identify a network of several neuroanatomical regions exhibiting interrelated reduced gray matter in both child sexual offender groups relative to controls, comprising extensive clusters in the bilateral cerebellum and frontal lobe, as well as smaller clusters in the bilateral parietal, temporal, and occipital lobes, the bilateral basal ganglia, the medial cingulate and the hippocampus.

Conclusion

Our results speak to the interpretation that there are inter‐ and possibly connectivity‐related brain structural abnormalities in child sexual offenders that are not (only) pertaining to pedophilia per se. Interpretations and limitations of the present data are discussed and recommendations for future works are given.
Photolysis of 3‐Azido‐3‐phenyl‐3H‐isobenzofuran‐1‐one at Ambient and Cryogenic Temperatures†
Authors: Thenna‐Hewa Kosala , Sebastien William , Lemen Elaine M. , Karney William L. , Abe Manabu , Gudmundsdottir Anna D.
Published: August 2021

Although alkyl azides are known to typically form imines under direct irradiation, the product formation mechanism remains ambiguous as some alkyl azides also yield the corresponding triplet alkylnitrenes at cryogenic temperatures. The photoreactivity of 3‐azido‐3‐phenyl‐3H‐isobenzofuran‐1‐one (1) was investigated in solution and in cryogenic matrices. Irradiation (λ = 254 nm) of azide 1 in acetonitrile yielded a mixture of imines 2 and 3. Monitoring of the reaction progress using UV‐Vis absorption spectroscopy revealed an isosbestic point at 210 nm, indicating that the reaction proceeded cleanly. Similar results were observed for the photoreactivity of azide 1 in a frozen 2‐methyltetrahydrofuran (mTHF) matrix. Irradiation of azide 1 in an argon matrix at 6 K resulted in the disappearance of its IR bands with the concurrent appearance of IR bands corresponding to imines 2 and 3. Thus, it was theorized that azide 1 forms imines 2 and 3 via a concerted mechanism from its singlet excited state or through singlet alkylnitrene 11N, which does not intersystem cross to its triplet configuration. This proposal was supported by CASPT2 calculations on a model system, which suggested that the energy gap between the singlet and triplet configurations of alkylnitrene 1N is 33 kcal/mol, thus making intersystem crossing inefficient.
Antileishmanial potential of immunomodulator gallic acid against experimental murine visceral leishmaniasis
Authors: Keshav Poonam , Goyal Deepak Kumar , Kaur Sukhbir
Published: August 2021

The menace of the enfeebling disease leishmaniasis prevails due to the inaccessibility of effective vaccine and chemotherapy. Hence in the pursuit of finding novel alternative options with reasonable efficacy, immunomodulation, leishmanicidal activity and fewer side effects, screening of compounds from natural sources is needed. This study was focused on in vitro and in vivo antileishmanial screening of gallic acid (GA) against Leishmania donovani infection in BALB/c mice. GA showed in vitro parasiticidal activity and IC50 value of 19.59 ± 0.74 µg/ml and is able to arrest cell cycle at the sub‐G0/G1 phase. The therapeutic potential of gallic acid was assessed in the L. donovani‐infected BALB/c mice. GA reported a reduction in parasite burden and augmentation of CD4+ and CD8+ T lymphocytes. Also, the polarization of mouse immune status to protective Th1 response was evidenced by increased delayed‐type hypersensitivity response and levels of IgG2a, reactive oxygen species and nitric oxide. GA was reported to be safe and non‐toxic to human cell line THP‐1 and also to the liver and kidney of mice. Hence, the findings of the present study indicate the possible role of GA in the strengthening of host immune system and thus facilitating the clearance of leishmanial infection and conferring protection.
Emerging indicators of fish welfare in aquaculture
Authors: Barreto Michelle Orietta , Rey Planellas Sonia , Yang Yifei , Phillips Clive , Descovich Kris
Published: August 2021

As aquaculture continues to grow and intensify, there is an increasing public concern over the welfare of farmed fish. Stress and production‐related pathologies and repressed growth are examples of the challenges facing aquaculture, and their impacts could be minimised by effective identification of the early signs of impaired welfare. Many welfare monitoring methods have been recommended; however, continuous and reliable welfare monitoring in aquaculture is not yet widespread and commonplace. The aim of this scoping review was to present an overview of the most recent developments in fish welfare assessments with a specific focus on practical translation to the aquaculture industry. A keyword‐based search was undertaken to identify peer‐reviewed papers published between 2014 and 2020 in which a novel method with the potential to be used for the assessment of fish welfare in aquaculture was introduced. The results were sorted into two categories: non‐invasive and invasive methods. All methods were assessed for their advantages and disadvantages, potential applicability to aquaculture. Invasive methods were also ranked on their degree of impact. It is concluded that increased interest into fish welfare, in combination with more intelligent modern technology, has resulted in the development of newer and more refined alternatives to traditional methods of welfare assessment such as behaviour monitoring by 2D cameras and plasma cortisol evaluation. Although, in many cases, more research is needed before these methods are suitable for widespread industry use, studies that focus on increasing the precision, automation and practical applicability of these methods are a promising avenue for future research.
Covariate Powered Cross-Weighted Multiple Testing
Authors: Ignatiadis Nikolaos , Huber Wolfgang
Published: August 2021

A fundamental task in the analysis of data sets with many variables is screening for associations. This can be cast as a multiple testing task, where the objective is achieving high detection power while controlling type I error. We consider m hypothesis tests represented by pairs ((Pi,Xi))1≤i≤m of p-values Pi and covariates Xi, such that Pi⊥Xi if Hi is null. Here, we show how to use information potentially available in the covariates about heterogeneities among hypotheses to increase power compared to conventional procedures that only use the Pi. To this end, we upgrade existing weighted multiple testing procedures through the independent hypothesis weighting (IHW) framework to use data-driven weights that are calculated as a function of the covariates. Finite sample guarantees, for example false discovery rate control, are derived from cross-weighting, a data-splitting approach that enables learning the weight-covariate function without overfitting as long as the hypotheses can be partitioned into independent folds, with arbitrary within-fold dependence. IHW has increased power compared to methods that do not use covariate information. A key implication of IHW is that hypothesis rejection in common multiple testing setups should not proceed according to the ranking of the p-values, but by an alternative ranking implied by the covariate-weighted p-values.
Leveraging the Fisher Randomization Test using Confidence Distributions: Inference, Combination and Fusion Learning
Authors: Luo Xiaokang , Dasgupta Tirthankar , Xie Minge , Liu Regina Y.
Published: August 2021

The flexibility and wide applicability of the Fisher randomization test (FRT) make it an attractive tool for assessment of causal effects of interventions from modern-day randomized experiments that are increasing in size and complexity. This paper provides a theoretical inferential framework for FRT by establishing its connection with confidence distributions. Such a connection leads to development’s of (i) an unambiguous procedure for inversion of FRTs to generate confidence intervals with guaranteed coverage, (ii) new insights on the effect of size of the Monte Carlo sample on the estimation of a p-value curve and (iii) generic and specific methods to combine FRTs from multiple independent experiments with theoretical guarantees. Our developments pertain to finite sample settings but have direct extensions to large samples. Simulations and a case example demonstrate the benefit of these new developments.
The Confidence Interval Method for Selecting Valid Instrumental Variables
Authors: Windmeijer Frank , Liang Xiaoran , Hartwig Fernando P. , Bowden Jack
Published: August 2021

We propose a new method, the confidence interval (CI) method, to select valid instruments from a larger set of potential instruments for instrumental variable (IV) estimation of the causal effect of an exposure on an outcome. Invalid instruments are such that they fail the exclusion conditions and enter the model as explanatory variables. The CI method is based on the CIs of the per instrument causal effects estimates and selects the largest group with all CIs overlapping with each other as the set of valid instruments. Under a plurality rule, we show that the resulting standard IV, or two-stage least squares (2SLS) estimator has oracle properties. This result is the same as for the hard thresholding with voting (HT) method of Guo et al. (Journal of the Royal Statistical Society : Series B, 2018, 80, 793–815). Unlike the HT method, the number of instruments selected as valid by the CI method is guaranteed to be monotonically decreasing for decreasing values of the tuning parameter. For the CI method, we can therefore use a downward testing procedure based on the Sargan (Econometrica, 1958, 26, 393–415) test for overidentifying restrictions and a main advantage of the CI downward testing method is that it selects the model with the largest number of instruments selected as valid that passes the Sargan test.
Erasing and dehumanizing Natives to protect positive national identity: The Native mascot example
Authors: Dai Juntao Doris , Lopez Julisa J. , Brady Laura M. , Eason Arianne E. , Fryberg Stephanie A.
Published: August 2021

For individuals who view being American as central to their sense of self, the reality of Native oppression (e.g., genocide, police brutality) threatens their ability to maintain a positive national identity. We theorize that long‐standing narratives in American culture erase and dehumanize Natives, enabling non‐Natives to psychological distance and justify Native oppression as a means of protecting positive national identity. We illustrate this protective process using the example of Native mascots. We first demonstrate that Native mascots erase and dehumanize Natives and then illustrate how the use of Native mascots protects national identity. We conclude by calling for individual‐ and institutional‐level changes to create a society free of harmful and toxic narratives and the practices that perpetuate these narratives.
Identifying hyperelastic constitutive parameters with sensitivity‐based virtual fields
Authors: Tayeb Adel , Le Cam Jean Benoît , Grédiac Michel , Toussaint Evelyne , Robin Eric , Balandraud Xavier , Canévet Frédéric
Published: August 2021

This work deals with the identification of hyperelastic constitutive parameters using the virtual fields method. The choice of the virtual displacement fields is a crucial aspect of the method, typically for reducing the sensitivity to the measurement noise. A first and simple option is to generate the virtual displacement fields randomly. Nevertheless, in case of hyperelastic models for which the stress is not a linear function of the constitutive parameters, improving the choice of the virtual displacement fields is not trivial and an alternative strategy has to be found. In the present study, the sensitivity‐based virtual fields approach is applied and compared with the randomly generated virtual displacement fields approach. Two material models were considered: the Mooney model, which describes quite well the behavior of hyperelastic materials for small and moderate strains, and the Ogden model, which accounts for the stress hardening phenomenon observed at higher strains. The full kinematic fields are measured by using the digital image correlation technique during an equibiaxial tensile test performed on a cruciform specimen. Identification results are discussed through their capability to predict the external force measured during the test. The sensitivity‐based virtual fields approach is found to improve significantly the prediction compared with the randomly generated virtual displacement fields approach.
Chalmers and Semantics
Authors: Raatikainen Panu
Published: August 2021

Abstract

David Chalmers' two‐dimensionalism is an ambitious philosophical program that aims to ground or construct Fregean meanings and restore “the golden triangle” of apriority, necessity, and meaning that Kripke seemingly broke. This paper aims to examine critically what Chalmers' theory can in reality achieve. It is argued that the theory faces severe challenges. There are some gaps in the overall arguments, and the reasoning is in some places somewhat circular. Chalmers' theory is effectively founded on certain strong philosophical assumptions. It is concluded that it is unclear whether the theory can deliver all it promises.
Evaluating the cascade of care for hypertension in Sierra Leone
Authors: Geraedts Tessa J. M. , Boateng Daniel , Lindenbergh Karel C. , van Delft Diede , Mathéron Hanna M. , Mönnink Gulia L. E. , Martens Janine P. J. , van Leerdam Daniel , Vas Nunes Jonathan , Bu‐Buakei Jabbi Sonnia‐Magba , Kpaka Mohamed S. , Westendorp Josien , van Duinen Alex J. , Sankoh Osman , Grobusch Martin P. , Bolkan Håkon A. , Klipstein‐Grobusch Kerstin
Published: August 2021

Objective

To assess the care for hypertension in Sierra Leone, by the use of a cascade‐of‐care approach, to identify where the need for healthcare system interventions is greatest.

Methods

Using data from a nationwide household survey on surgical conditions undertaken in 1956 participants ≥18 years from October 2019 to March 2020, a cascade of care for hypertension consisting of four categories – hypertensive population, those diagnosed, those treated and those controlled – was constructed. Hypertension was defined as having a blood pressure ≥140/90 mmHg, or self‐reported use of antihypertensive medication. Logistic regression analysis was used to investigate factors associated with undiagnosed hypertension.

Results

The prevalence of hypertension was 22%. Among those with hypertension, 23% were diagnosed, 11% were treated and 5% had controlled blood pressure. The largest loss to care (77%) was between being hypertensive and receiving a diagnosis. Male sex, age and living in a rural location, were significantly associated with the odds of undiagnosed hypertension. There was no significant difference between men and women in the number of patients with controlled blood pressure. Adults aged 40 or older were observed to be better retained in care compared with those younger than 40 years of age.

Conclusion

There is a significant loss to care in the care cascade for hypertension in Sierra Leone. Our results suggest that increasing awareness of cardiovascular risk and risk factor screening for early diagnosis might have a large impact on hypertension care.
Outcomes of nine cats with urinary retention after sacrocaudal luxation managed with long‐term urinary diversion
Authors: Garcia Marcos , Dumartinet Caroline , Bernard Fabrice , Bernardé Antoine
Published: August 2021

Objective

To document the outcomes of cats with urinary retention (UR) after sacrocaudal luxation (SCL) and managed with a long‐term cystostomy (LTC).

Study Design

Short case series.

Animals

Nine client‐owned cats with SCL and subsequent UR.

Methods

Nine cats suffering from non‐relievable UR secondary to SCL, between March 2013 and December 2020, had a LTC placed 4.5 days post‐SCL (mean, range 3.5–6.0), until clinical evidence of normal urination recovery. The bladder was emptied at least twice daily. No antimicrobial was given during LTC. Indication for tube removal was voluntary micturition with complete emptying for a minimum of three consecutive days. Recheck examinations were scheduled for post‐SCL days 7 and 14, as well as for LTC tube removal. Minor and major complications and length of LTC use were recorded.

Results

The LTC was removed 11–42 days (mean 26 days) after placement. All cats recovered normal micturition spontaneously within 17–47 days post‐SCL (mean 30.7 days): 1 cat between the 2nd and 3rd weeks, 5 cats between the 3rd and 4th weeks, and 3 cats >30 days after the trauma. Major complications, such tube dislodgement, occurred in two cats, whereas complications resolving after tube removal were recorded in 6 cats.

Conclusion

LTC was effective at managing UR post‐SCL in 9 cats. All cats recovered normal urinary function within 7 weeks.

Clinical Significance

LTC can be an alternative to manual expression or bladder catheterization in cats with temporary UR after SCL.
Exploring the use of simulation to develop leadership skills in undergraduate nursing students: a scoping review protocol
Authors: Huynh Ngoc
Published: August 2021

Objective:

This review will explore the use of simulation to develop leadership skills in nursing students in undergraduate nursing education programs.

Introduction:

Leadership skills are traditionally incorporated into nursing curriculum as a stand-alone course. A demonstrated need for leadership skills in nursing graduates and recent evidence on the effectiveness of simulation in nursing education programs has led to increased use of simulation to develop leadership skills in undergraduate nursing students. Identification, explication, and mapping of the various strategies are required to help advance the use of simulation to develop leadership skills in nursing education.

Inclusion criteria:

Papers that focus on the use of simulation strategies specifically related to the development of nursing leadership skills in undergraduate nursing students will be included. Papers focused on post-registration/licensure nurses, graduate nurses, nurse practitioners, midwives, allied health care professionals, or psychomotor nursing skills will be excluded.

Methods:

This review will be conducted in accordance with JBI methodology for scoping reviews and will consider English-language literature from 2000 to the present. Data will be extracted from the following databases: CINAHL Plus with Full Text (EBSCO); MEDLINE (R) and Epub Ahead of Print (Ovid), In-Process, In-Data-Review and Other Non-Indexed Citations, and Daily and Versions (R); PsycINFO (Ovid); Embase (Ovid); ERIC (EBSCO); and ProQuest Nursing and Allied Health Source. The search will also include unpublished non-peer-reviewed literature.
Contribuição à Geologia da Região de Frades, Município de Teresópolis (Rio de Janeiro)
Authors: Baptista Filho João , Gomes Benedito Souza , Silva Francisco José da
Published: August 2021

A geological mapping at the scale 1:50,000 based on air photographs at the scale 1:20.000 is being held near Frades, a small village between Teresopolis and Nova Friburgo, State of Rio de Janeiro, Brazil. The main rock types are a coarse grained gneiss, migmatites and granites. The pigmatites exibits a dark differentiate (melanosome), sometimes widespread in area, which has been mapped as amphibolite sensu strictu. The latter, until now considered of magmatic origin, seems to have formed through migmatization processes.
Aplicação da Análise de Correlação em Fotometria Astronômica
Authors: Vieira Jorge De Albuquerque
Published: August 2021

An application is made of the computation of autocorrelation functions as indicators of the syntactic content of photometric astronomical signals. A resolution function is designed to evidence, in such signals structures of interest.
Evolução da Hierarquia Urbana Segundo Fluxos Aéreos no Brasil no Período de 1965 a 1973
Authors: Freire Lucy A. R. , Sant'Anna Marina
Published: August 2021

This article presents the results of a study of interurban air travel in Brazil, where the influence of distance on traffic generation is analysed based in one of the must widely known of the hypotheses about the density of intercity travel which suggest that the number of trips occurring between two cities is greater as the populations of the two cities are larger and smaller as the two cities are farther apart. The method used is the comparation of a true hierarchical pattern (based in the number of passengers between the cities with a the oretical one in two different periods of time to ascertain the evolution of this relationship.
Numerical Analysis of SS316L Biaxial Cruciform Specimens Under Proportional Loading Paths
Authors: Mamros Elizabeth M. , Eaton Matthew C. , Ha Jinjin , Kinsey Brad L.
Published: August 2021

In this paper, finite element analyses were conducted to investigate the stress and strain states resulting from varying the deformation of stainless steel 316L under biaxial loading. To that end, a biaxial specimen geometry was designed in collaboration with the US National Institute of Standards and Technology (NIST) to achieve large and uniform strain values in the central pocket region. Special care was taken to ensure that the specimen design could be readily manufactured with available resources. Simultaneously, the specimen design criteria required an acceptable strain uniformity in a sufficiently large pocket section to allow for accurate deformation and austenite to martensite phase fraction measurements. This demonstrates the concept of altering the final material properties through stress superposition. Numerical results show that nearly linear curves were observed in the strain path plots. The minimum uniform deformation area for the 4:1 case had a radius of ∼1 mm, which is sufficient for experimental analyses, e.g., digital imaging correlation and electron beam backscatter diffraction. As an application for such heterogeneous materials, patient specific trauma fixation hardware, which are surgically implanted to set broken bones during healing, require high strength in areas where screws are located, i.e., martensite phase, yet low weight elsewhere.
Molecular Dynamics Modeling the Nano-Identation of Titanium
Authors: Yang Peiqiang , Zhang Xueping , Yao Zhenqiang , Shivpuri Rajiv
Published: August 2021

Titanium alloys’ excellent mechanical and physical properties make it the most popular material widely used in aerospace, medical, nuclear and other significant industries. The study of titanium alloys mainly focused on the macroscopic mechanical mechanism. However, very few researches addressed the nanostructure of titanium alloys and its mechanical response in Nano-machining due to the difficulty to perform and characterize nano-machining experiment. Compared with nano-machining, nano-indentation is easier to characterize the microscopic plasticity of titanium alloys. This research presents a nano-indentation molecular dynamics model in titanium to address its microstructure alteration, plastic deformation and other mechanical response at the atomistic scale. Based on the molecular dynamics model, a complete nano-indentation cycle, including the loading and unloading stages, is performed by applying Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). The plastic deformation mechanism of nano-indentation of titanium with a rigid diamond ball tip was studied under different indentation velocities. At the same time, the influence of different environment temperatures on the nano-plastic deformation of titanium is analyzed under the condition of constant indentation velocity. The simulation results show that the Young’s modulus of pure titanium calculated based on nano-indentation is about 110GPa, which is very close to the experimental results. The results also show that the mechanical behavior of titanium can be divided into three stages: elastic stage, yield stage and plastic stage during the nano-indentation process. In addition, indentation speed has influence on phase transitions and nucleation of dislocations in the range of 0.1–1.0 Å/ps.
Synthesis of Nanoporous Gold by Chemical Dealloying of Co-Sputtered Gold-Silver Thin Films and Study of Its Variability
Authors: Niauzorau Stanislau , Sharstniou Aliaksandr , Kublik Natalya , Sampath Venkata Krishnan , Azeredo Bruno
Published: August 2021

In the past two decades, nanoporous metals have attracted wide attention in the areas of energy storage, biomedicine and catalysis. Compared to other metals, nanoporous gold exhibits superior chemical stability, high catalytic activity, and its synthesis is facile and well documented. While many studies elaborate on the dealloying kinetics to understand process-structure relationships, its process variability is known to be large and yet not well documented. In this study, nanoporous gold was synthesized by chemical dealloying of co-sputtered gold-silver thin film. By controlling temperature and time during dealloying, its porosity characteristics, such as ligament diameter and solid area fraction, were controlled. Further, the time evolution of structural and elemental characteristics of nanoporous gold were examined including its correlation to silver residual content. It is found that mean diameters grow as a function of etch time from 25 to 60 nm. The large standard deviation (18.6 nm) of multiple dealloying attempts at any given temperature and dealloying time points to the lack of control in the kinetics of the dealloying reaction and variability in its substrate preparation and processing protocols. A comprehensive analysis of these parameters might provoke a better understanding of nanoporous gold synthesis in terms of the structure evolution kinetics.
A Novel Packing Hollow Dodecahedron Model to Study the Mechanical and Thermal Properties of Stocastic Metallic Foams
Authors: Dai Rui , Kwon Beomjin , Nian Qiong
Published: August 2021

Stochastic foam with hierarchy order pore structure possesses distinguished physical properties such as high strength to weight ratio, super lightweight, and extremely large specific area. These exceptional properties make stochastic foam as a competitive material for versatile applications e.g., heat exchangers, battery electrodes, automotive components, magnetic shielding, catalyst devices and etc. Recently, the more advanced hollow cellular (shellular) architectures with well-developed structure connections are studied and expected to surpass the solid micro/nanolattices. However, in terms of theoretical predicting and studying of the cellular foam architecture, currently no systematic model can be utilized to accurately capture both of its mechanical and thermal properties especially with hollow struts due to complexity induced by its stochastic and highly reticulate nature. Herein, for the first time, a novel packing three-dimensional (3D) hollow dodecahedron (HPD) model is proposed to simulate the cellular architecture. An electrochemical deposition process is utilized to manufacture the metallic foam with hollow struts. Mechanical and thermal testing of the as-manufactured foams are carried out to compare with the HPD model. HPD model is proved to accurately capture both the topology and the physical properties of stochastic foam at the similar relative density. Particularly, the proposed model makes it possible to readily access and track the physical behavior of stochastic foam architecture. Accordingly, this work will also offer inspiration for designing an efficient foam for specific applications.
Time Domain Simulation of Dynamic Corner Milling Process Considering Chatter Vibration With Finite Amplitude
Authors: Suzuki Norikazu , Hayashi Hiroki , Shamoto Eiji , Irino Naruhiro , Imabeppu Yasuhiro
Published: August 2021

A number of analysis methods for the process with chatter vibration have been proposed so far. These methods can be used to improve processes stability resulting in better production efficiency. However, the poor estimation accuracy of the phenomenon severely limits the performance of process optimization using the simulation-assisted approach. One of the causes of accuracy deterioration is the modeling error of the phenomenon accompanied by chatter vibration with finite amplitude. In this study, we developed a model that can consider the non-linear uncut chip thickness fluctuation caused by the influence of finite amplitude and the process damping due to the contact of the tool flank face against the finished workpiece surface. Furthermore, we developed a time domain simulator that implements the proposed model, and estimated the finished surface profile of the workpiece based on the results of the time domain simulation. To verify the proposed method, corner machining experiments with an end mill were conducted. Corner machining is frequently used in industrial, but it is known that chatter vibration is likely to occur. In corner machining, machine tools generate motions that accompany acceleration and deceleration. The motion of this feed drive system strongly depends on the dynamic characteristics of the machine tool and the trajectory generation algorithm, which greatly affects the emersion angle of the cutter. Therefore, we simulated the dynamic corner machining process considering the measured data of the motion trajectory of the feed drive system. The estimation result of chatter vibration in corner machining is in good agreement with the measurement result of the machining process. In addition, high-precision estimation of the machined surface profile with chatter mark has been realized.
Computational Study of Reinforcement Mechanisms of Cuttlefish Bone Inspired Structure for 3D Printing
Authors: Bethers Brandon , Yang Yang
Published: August 2021

Cuttlebone, the internal shell structure of a cuttlefish, presents a unique labyrinthian wall-septa design that promotes high energy absorption, porosity, and damage tolerance. This structure offers us an inspiration for the design of lightweight and strong structures for potential applications in mechanical, aerospace and biomedical engineering. However, the complexity of the cuttlebones structural design makes its fabrication by traditional manufacturing techniques not feasible. The advances in additive manufacturing (3D printing) make highly complex structures like cuttlebone possible to manufacture. In this work, the authors sought to establish comparative data between cuttlebone structures and some common support structures used in additive manufacturing. The structures compared to cuttlebone in this work include the cubic, honeycomb and triangular support structures. This was accomplished by using CAD modeling and simulation software. This study found that the cuttlefish structures had higher average stress values than the others but similar average strain values. This leads to a higher modulus of elasticity for the cuttlebone structures. The data suggests that further research into cuttlebone structures could produce future designs that improve upon the current well-established additive manufacturing support structures. Further study will be performed for the 3D printing of cuttlebone inspired structures by using various types of materials, such as soft and rigid polymers, functional ceramics, composites, and metals.
Magnetic Field Assisted 3D Printing of Limpet Teeth Inspired Polymer Matrix Composite With Compression Reinforcement
Authors: Joralmon Dylan , Amonoo Evangeline , Zhu Yizhen , Li Xiangjia
Published: August 2021

Lightweight and cost-effective polymer matrix composites (PMCs) with extraordinary mechanical performance will be a key to the next generation of diverse industrial applications such as aerospace, electric automobile, and biomedical devices. Limpet teeth made of mineral-polymer composites have been proved as nature’s strongest material due to the unique hierarchical architectures of mineral fiber alignment. Here, we present an approach to build limpet teeth inspired structural materials with precise control of geometric morphologies of microstructures by magnetic field-assisted 3D printing (MF-3DP). α-Iron (III) oxide-hydroxide nanoparticles (α-FeOOHs) are aligned by the magnetic field during 3D printing and aligned α-FeOOHs bundles are further grown to aligned goethite-based bundles (aGBs) by rapid thermal treatment after printing. The mechanical reinforcement of goethite-based fillers in PMCs can be modulated by adjusting the geometric morphology and alignment of mineral particles encapsulated inside the 3D printed PMCs. In order to identify the mechanical enhancement mechanism, physics-based modeling, simulation, and tests were conducted and the results further guided the design of bioinspired goethite-based PMCs. The correlation of the geometric morphology of self-assembled α-FeOOHs, curing characteristics of α-FeOOHs/polymer composite, and process parameters were identified to establish the optimal design of goethite-based PMCs. The 3D-printed PMCs with aGBs show promising mechanical reinforcement. This study opens intriguing perspectives for designing high strength 3D printed PMCs on the basis of bioinspired architectures with customized configurations.
Chipping Reduction Using Thermally-Assisted Friction Element Welding
Authors: Deshpande Amit B. , Grimm Tyler J. , Mears Laine
Published: August 2021

The use of multiple material in the structural components of a vehicle allows for significant weight reduction. Friction element welding (FEW) is a novel method that allows the joining of two or more dissimilar material sheets. A limitation of this process is the chip formation in high strength aluminum alloys, which is observed as the protrusion of thin aluminum segments from under the head of the fastener. Chipping can degrade the joint’s strength over time due to accelerated crevice corrosion.

A novel method is proposed to eliminate chip formation using thermal assistance. A grading scheme is developed to quantify the severity of chip formation. The effect of thermal assistance on chipping is analyzed. An investigation is also carried out to validate that the thermal assistance does not negatively affect the process time, energy, and joint strength. Thermal assistance is proposed to be a novel method of overcoming this limitation to allow more widespread use of the FEW process for higher-strength aluminum alloys. Future work will include the development of feasible, rapid methods of heating and measurement of energy utilization for implementation in the industrial environment.
A Flexible Similarity Based Algorithm for Tool Condition Monitoring
Authors: Stuhr Ben , Liu Rui
Published: August 2021

To realize smart manufacturing in various machining processes, tool condition monitoring (TCM) systems are employed to detect the state of the tool in optimizing tool conditions and preventing catastrophic failures. Common types of TCM systems include part-specific methods and generic methods. However, many developed TCM systems lack flexibility and require extensive set-up. To address these issues, the proposed algorithm takes advantage of repetitive machining operations in manufacturing settings and adopts similarity analysis to realize tool condition monitoring by comparing the signals collected from the tool with known conditions against the signals generated by the tool to be monitored. To validate the effectiveness of the proposed TCM system, a case study was performed in which the power signal was collected and used in the similarity analysis. According to this case study, it has been proven that the proposed TCM algorithm is able to accurately predict the state of the tool, i.e. tool wear, with a very simple and flexible solution. Furthermore, several tool condition induced machining parameters have been evaluated to satisfy various monitoring requirements. Nearly all evaluated machining parameters validated the performance and flexibility of the TCM algorithm.
Swedish Manufacturing Practices Towards a Sustainability Transition in Industry 4.0: A Resilience Perspective
Authors: Chari Arpita , Duberg Johan Vogt , Lindahl Emma , Stahre Johan , Despeisse Mélanie , Sundin Erik , Johansson Björn , Wiktorsson Magnus
Published: August 2021

The Swedish strategic innovation programme, Produktion2030, is a national long-term effort towards global industrial competitiveness addressing Swedish industry’s transition towards climate goals of the European Green Deal while simultaneously realising smart manufacturing and Industry 4.0 (I4.0). This paper investigated the extent of sustainability implementation and implications of I4.0 technologies through a nation-wide quantitative survey in Produktion2030’s 113 collaborative research projects. The analysis showed that 71% of the assessed projects included environmental aspects, 60% social aspects, and 45% Circular Economy (CE) aspects. Further, 65% of the projects implemented I4.0 technologies to increase overall sustainability. The survey results were compared with literature to understand how I4.0 opportunities helped derive sustainability and CE benefits. This detailed mapping of the results along with eight semi-structured interviews revealed that a majority of the projects implemented I4.0 technologies to improve resource efficiency, reduce waste in operations and incorporate CE practices in business models. The results also showed that Swedish manufacturing is progressing in the right direction of sustainability transition by deriving key resilience capabilities from I4.0-based enablers. Industries should actively adopt these capabilities to address the increasingly challenging and unpredictable sustainability issues arising in the world and for a successful transition towards sustainable manufacturing in a digital future.
An Augmented-Reality Based Human-Robot Interface for Robotics Programming in the Complex Environment
Authors: Yang Wenhao , Xiao Qinqin , Zhang Yunbo
Published: August 2021

To solve the problems of complex robot programming tasks, we propose an Augmented Reality (AR) based human-robot interface for planning a collision-free path in a complex environment. Current robot programming methods usually require a high level of experience in robot programming (online programming), the time-consuming 3D modeling of the working environment for collision detection (offline programming), and a tedious and inefficient re-planing to adapt environment or task changes (both online and offline programming). In order to address these problems, an end-to-end AR human-robot interface is proposed, which provides a new affordance to users by enabling them to plan the path in the AR environment. A set of user-interactive tools allow users to define and edit waypoints as the high-level guidance and the direct inputs for the toolpath planning package, Kinematics and Dynamics Library (KDL). With the fast sensing of the workspace and accurate rendering, an in-situ simulation module is utilized for collision check and verification by the users’ perception. Users will repeat the process of 1) waypoints definition and editing, and 2) the collision checking and path feasibility verification, until a satisfactory path is obtained. A preliminary testing is conducted in a use case with complex obstacles to verified the effectiveness and the efficiency of the proposed interface.