bluuebunny/crossref_metadata_2025 huggingface dataset:
The epistemic and pragmatic function of dichotomous claims based on statistical hypothesis tests
Authors: Uygun Tunç Duygu , Tunç Mehmet Necip , Lakens Daniël
Published: March 2023

Researchers commonly make dichotomous claims based on continuous test statistics. Many have branded the practice as a misuse of statistics and criticize scientists for the widespread application of hypothesis tests to tentatively reject a hypothesis (or not) depending on whether a p-value is below or above an alpha level. Although dichotomous claims are rarely explicitly defended, we argue they play an important epistemological and pragmatic role in science. The epistemological function of dichotomous claims consists in transforming data into quasibasic statements, which are tentatively accepted singular facts that can corroborate or falsify theoretical claims. This transformation requires a prespecified methodological decision procedure such as Neyman-Pearson hypothesis tests. From the perspective of methodological falsificationism these decision procedures are necessary, as probabilistic statements (e.g., continuous test statistics) cannot function as falsifiers of substantive hypotheses. The pragmatic function of dichotomous claims is to facilitate scrutiny and criticism among peers by generating contestable claims, a process referred to by Popper as “conjectures and refutations.” We speculate about how the surprisingly widespread use of a 5% alpha level might have facilitated this pragmatic function. Abandoning dichotomous claims, for example because researchers commonly misuse p-values, would sacrifice their crucial epistemic and pragmatic functions.
Estimating individualized treatment rules in longitudinal studies with covariate-driven observation times
Authors: Coulombe Janie , Moodie Erica EM , Shortreed Susan M , Renoux Christel
Published: March 2023

The sequential treatment decisions made by physicians to treat chronic diseases are formalized in the statistical literature as dynamic treatment regimes. To date, methods for dynamic treatment regimes have been developed under the assumption that observation times, that is, treatment and outcome monitoring times, are determined by study investigators. That assumption is often not satisfied in electronic health records data in which the outcome, the observation times, and the treatment mechanism are associated with patients’ characteristics. The treatment and observation processes can lead to spurious associations between the treatment of interest and the outcome to be optimized under the dynamic treatment regime if not adequately considered in the analysis. We address these associations by incorporating two inverse weights that are functions of a patient’s covariates into dynamic weighted ordinary least squares to develop optimal single stage dynamic treatment regimes, known as individualized treatment rules. We show empirically that our methodology yields consistent, multiply robust estimators. In a cohort of new users of antidepressant drugs from the United Kingdom’s Clinical Practice Research Datalink, the proposed method is used to develop an optimal treatment rule that chooses between two antidepressants to optimize a utility function related to the change in body mass index.
Modeling unmeasured baseline information in observational time-to-event data subject to delayed study entry
Authors: Stegherr Regina , Beyersmann Jan , Bramlage Peter , Bluhmki Tobias
Published: March 2023

Unmeasured baseline information in left-truncated data situations frequently occurs in observational time-to-event analyses. For instance, a typical timescale in trials of antidiabetic treatment is “time since treatment initiation”, but individuals may have initiated treatment before the start of longitudinal data collection. When the focus is on baseline effects, one widespread approach is to fit a Cox proportional hazards model incorporating the measurements at delayed study entry. This has been criticized because of the potential time dependency of covariates. We tackle this problem by using a Bayesian joint model that combines a mixed-effects model for the longitudinal trajectory with a proportional hazards model for the event of interest incorporating the baseline covariate, possibly unmeasured in the presence of left truncation. The novelty is that our procedure is not used to account for non-continuously monitored longitudinal covariates in right-censored time-to-event studies, but to utilize these trajectories to make inferences about missing baseline measurements in left-truncated data. Simulating times-to-event depending on baseline covariates we also compared our proposal to a simpler two-stage approach which performed favorably. Our approach is illustrated by investigating the impact of baseline blood glucose levels on antidiabetic treatment failure using data from a German diabetes register.
Mechanical properties of starch bio-composite and molded pulp samples manufactured using pine and eucalyptus fibers
Authors: Alptekin Artunç , Çallioğlu Hasan
Published: March 2023

In recent years, one of the main challenges is to improve the mechanical performance of bio-composites to be used as structural parts for the construction, automotive, and aviation sector. This paper may contribute to developing durable structural bio-composite parts with starch addition. The mechanical properties of bio-composites reinforced by eucalyptus or pine fibers (48 wt %) compound with Cationic Starch (48 wt %) and Carboxymethyl cellulose (CMC) (4 wt %) were determined. The production method was a combination of molded pulp, extrusion, and compression molding production techniques. To see the effect of adding starch to bio-composites and different production methods, the mechanical performance of these natural fibers produced by the conventional molded pulp production method (without any additives) was also found and compared with the composite samples. Composite samples indicate significantly better tensile, flexural, and compressive values, at least four times, compared with the molded pulp samples. On the other hand, the molded pulp samples had more than 2 times better impact characteristics against composites. Using molded pulp technic in composite production (investigated in the study) is a new idea and may give some opportunities with its serial production compatibility and geometry freeness, to the industry.
Clientelism and Subservience in Organizational Behaviour and Professional Practice
Authors: Nekmahmud Md. , Patwary Masum A.
Published: March 2023

The purpose of this qualitative study was to discuss the opinions of diverse employees in a developing country where social inequalities, stratification and behavioural attitudes encourage the type of subservient behaviour and clientelistic attitudes that impact organizational behaviour and a tendency towards corruption. A range of qualitative techniques, such as observation, third-person listening, formal and informal dialogue and an in-depth interview approach was adopted to collect data from selected participants through a non-probability sampling strategy. An extreme lack of professional behaviour was observed. The qualitative study of contributions and motivations to these practices reveals a misunderstanding of professional etiquette, leading to a culture of senior officials and subordinate relationships (corruption), lack of responsibility and accountability and negative impacts on organizational policy implementation. The research revealed that networks may have a layered system that informs the activities of actors involved in organizational management. This study is the first evidence that subservient attitudes and senior-subordinate relationships may cause barriers to the execution of professional attitudes and other official rules and norms.
The Impact of ICT on Financial Sector Development Under Structural Break: An Empirical Analysis of the Turkish Economy
Authors: Shahbaz Muhammad , Çetin Murat , Avcı Pınar , Sarıgül Sevgi Sümerli , Topcu Betül Altay
Published: March 2023

This study is to examine the relationship between information and communication technology (ICT) and financial development in the Turkish economy during the period of 1986–2018. By empirical literature, economic growth, technological innovation, and financial globalization are added to the financial development model as explanatory variables. The autoregressive distributed lag (ARDL) model and Hatemi-J cointegration test with two structural breaks are applied to examine the presence of cointegration between the variables. Dynamic ordinary least squares (DOLS), fully modified least squares (FMOLS), and canonical cointegrating regression (CCR) estimation techniques are applied for long-term estimates. The vector error correction model (VECM) Granger causality approach is used for causality analysis. Our empirical results show that under the structural break, ICT, economic growth, technological innovation, and financial globalization are cointegrated with financial development. In the presence of a structural break, ICT and technological innovation negatively affect financial development, while economic growth and financial globalization have a positive impact on financial development. The causality analysis determines that there is a one-way causality relationship running from ICT and economic growth to financial development. In addition, technological innovation and financial globalization lead to long-term financial development. Empirical findings have important policy recommendations for financial development in the Turkish economy.
Defining the fit and ideal entry site of the fibula rod system––a computed tomography based study in elderly patients with lower limb infections, vascular diseases or tumors
Authors: Cheung Yan Chun , Yee Dennis KH , Fang Christian
Published: March 2023

Objectives

To determine the configuration of the distal fibula anatomy and the fitness of the Fibula Rod System (Acumed®, Hillsboro, Oregon) in a series of fibula models and to determine the optimal entry site of the rod.

Methods

Consecutive series of computed tomography (CT) of tibias and fibulae with no fracture or deformity were converted to stereo-lithograph format, and imported into Meshmixer software (Autodesk, San Rafael, California). A 3.6 × 180 mm fibula rod model was virtually inserted to best fit the intramedullary canal of the fibula model and to a depth of 0 mm proud at the distal fibula. The location of the entry point in relationship to the fibular tip, and the distance between the rod and the lateral fibula cortex were measured.

Results

CT of 41 fibulae (23 male and 18 female patients) contributed to the three-dimensional fibula modeling. The entry point was 3.5 mm (SD 2.0) medial to (in mortise view) and 1.0 mm (SD 2.1) anterior to (in lateral view) the fibular tip. The fibula rod was inserted to a depth of 6.2 mm (SD 2.1) proximal to the fibula tip. The mean shortest distance of the rod to the outer cortex was 1.88 mm (SD 0.87). There was a breach of the posterolateral cortex in one patient.

Conclusion

The guide pin entry site of fibula rod should be medial and anterior offset with reference to the fibula tip, in contrary to the distal tip as recommended in the manual. There is a chance of breaching the posterolateral cortex with rod entry.
Passion, music, and psychological well-being
Authors: Powell Merrick , Olsen Kirk N. , Vallerand Robert J. , Thompson William Forde
Published: March 2023

Passionate music engagement is a defining feature of music fans worldwide. Although benefits to psychosocial well-being are often experienced by fans of music, some fans experience maladaptive outcomes from their music engagement. The Dualistic Model of Passion proposes that two types of passion—harmonious and obsessive—are associated with positive and negative outcomes of passionate engagement, respectively. This model has been employed in research on passion for a wide range of pursuits including music performers, but not for passionate listeners. The present study employed this model to investigate whether (1) harmonious passion for music is associated with positive music listening experiences and/or psychological well-being and (2) obsessive passion for music is associated with negative music listening experiences and/or psychological ill-being. Passionate fans ( n = 197) of 40 different musical genres were surveyed about their experiences when listening to their favorite music. Measures included the passion scale, affective experiences with music, and psychological well-being and ill-being. Results supported the Dualistic Model of Passion. Structural equation modeling revealed that harmonious passion for music predicted positive affective experiences which, in turn, predicted psychological well-being. Conversely, obsessive passion for music predicted negative affective experiences which, in turn, predicted psychological ill-being. The findings suggest that the nature of passionate engagement with music has an integral role in the psychological impact of music engagement and implications for the well-being of music fans.
Medium- to Long-term Results of Nonanatomic Spring Ligament Reconstruction Using an Allograft Tendon in Progressive Collapsing Foot Deformity With Severe Abduction Deformity
Authors: Kim Jaeyoung , Mizher Rami , Sofka Carolyn M. , Ellis Scott J. , Deland Jonathan T.
Published: March 2023

Background:

Spring ligament reconstruction (SLR) has been suggested as an adjunct to other reconstructive procedures to potentially avoid talonavicular joint fusion in progressive collapsing foot deformity (PCFD) with severe abduction deformity. Most clinical reports present short-term follow-up data and a small number of patients. The purpose of this study was to examine the medium- to long-term outcomes of an SLR using allograft tendon augmentation as part of PCFD surgical reconstruction. This study to our knowledge represents the largest number of patients and the longest follow-up to date.

Methods:

This study retrospectively reviewed 26 patients (27 feet, mean age of 61.4 years) who underwent SLR with allograft tendon as part of PCFD reconstruction. The mean follow-up of the cohort was 8 years (range, 5-13.4). Radiographic evaluation consisted of 5 parameters including talonavicular coverage angle (TNC), with the maintenance of correction being evaluated by comparing parameters from the early postoperative period (mean: 11.6 months, range, 8-17) to final follow-up. Foot and Ankle Outcome Score (FAOS) and patient satisfaction questionnaires were collected at final follow-up. Conversion to talonavicular or subtalar fusion was considered as a failure.

Results:

Final radiographs demonstrated successful abduction correction, with the mean TNC improving from 43.7 degrees preoperatively to 14.1 degrees postoperatively (P < .0001). All other radiographic parameters improved significantly and exhibited maintenance of the correction. All FAOS subscales showed significant improvement. Responses to the satisfaction questionnaire were received from all except 1 patient, of whom 88.5% (23/26) were satisfied with the results, 96.2% (25/26) would undergo the surgery again, and 88.5% (23/26) would recommend the surgery. Eight feet (29.6%) required painful hardware removal and 1 (3.7%) developed nonunion of the lateral column lengthening osteotomy. No patient required conversion to talonavicular or subtalar fusion.

Conclusion:

This study demonstrates favorable medium- to long-term outcomes following PCFD reconstruction including an SLR with allograft tendon augmentation.

Level of Evidence:

Level IV, case series.
Suppress chatter in milling of thin-walled parts via fixture with active support
Authors: Dong Xingjian , Tu Guowei , Hu Lan , Peng Zhike
Published: March 2023

In this study, we designed an integrated fixture system using eddy current sensors and piezoelectric actuators. With this system, active supporting forces are exerted on thin-walled workpieces to adjust their stiffness in a real-time manner and thus to suppress chatter in milling. When modeling this system, we used a mass–stiffness–damping element to characterize the dynamic behavior of the actuator under high-speed responses, and we considered the electromechanical coupling between the mechanical elements and the drive circuit of the actuator. We then proposed an optimal delayed state feedback controller for the closed-loop system. The delayed state is obtained by introducing the time delay in milling dynamics into the regular state feedback, and the optimal gain is worked out through the differential quadrature and gradient descent, which is a much more computationally efficient method than the classic semi-discretization. Among all similar approaches, our strategy leads to the largest stability region for milling of thin-walled parts and requires the least energy input, which are proved by simulations and experiments.
Transborder Literacies of (In)Visibility
Authors: Gallo Sarah , Adams Corral Melissa
Published: March 2023

Drawing from an ethnography with mixed-status families residing in Mexico, we examine what we term transborder literacies of (in)visibility, or diasporic people's innovative interactions around texts that prepare them to move across incompatible mononational institutions divided by borders. Through close attention to the literacy practices families engaged in as they applied for their children's U.S. passports from Mexico, we demonstrate how these literacies were not just about expanding authentic ways of reading and writing to include both U.S. and Mexican ways, but instead required unique transborder literacies across mutually unintelligible, racializing mononational systems so that children could (re)access their rights on both sides of the border. We argue that recognizing families’ complex transborder literacy practices of (in)visibility could offer a novel anti-oppressive lens to transform how educators make sense of the complexity of immigrant families’ literacies, movements, and educational supports across borders and national schooling systems.
Neocolonial masculinities in Costa Rica: an analytical proposal
Authors: Ochoa Mauricio Menjívar
Published: March 2023

The article explains the concept of neocolonial masculinities. It aims to understand the practice of mestizo and white men in their contact, as agents of the State, with indigenous people. The three levels of analysis of the concept are explained: a) conditioning structures of the practice; b) guiding categories of the practice (class, masculinity and race), and c) intersectional practice. In agreement with other theoretical developments, it is concluded that masculinities must be captured from concrete practices, accounting for the bonds between structures and individuals.
Experience With a Non-Hormonal Centella Asiatica, Hyaluronic Acid and Prebiotic-Based Vaginal Gel in Women With Recurrent Vulvovaginal Candidiasis: Case Studies
Authors: Amorós Manuela , Mora Palma José Carlos , Esteve María , Salado Mercedes , Macatangga Mónica G , Aguarón Benítez Guadalupe , Luque Pablo , Cortés Javier
Published: March 2023

Recurrent vulvovaginal candidiasis (RVVC) affects millions of women worldwide, severely impairing their quality of life. Despite the existence of multiple induction and maintenance therapeutic strategies, mainly based on antifungals, relapse rates are still high. Palomacare® is a vaginal gel containing, among others, hyaluronic acid and Centella asiatica, with repairing and moisturizing properties. A series of 5 clinical cases showed that symptoms improved and even disappeared in women with RVVC receiving Palomacare®. None of the patients experienced recurrence after the treatment, having their vaginal health restored, suggesting that the non-hormonal Centella asiatica, hyaluronic acid and prebiotic-based gel is effective for preventing RVVC relapse in women of reproductive age.
Management of Acne Vulgaris With Trifarotene
Authors: Tan Jerry , Chavda Rajeev , Baldwin Hilary , Dreno Brigitte
Published: March 2023

Topical retinoids have an essential role in treatment of acne. Trifarotene, a topical retinoid selective for retinoic acid receptor (RAR) γ, is the most recent retinoid approved for treatment of acne. RAR-γ is the most common isoform of RARs in skin, and the strong selectivity of trifarotene for RAR-γ translates to efficacy in low concentration. Trifarotene, like other topical retinoids, acts by increasing keratinocyte differentiation and decreasing proliferation, which reduces hyperkeratinization. Retinoids have also been shown to inhibit inflammatory pathways via effects on leukocyte migration, toll-like receptors, and Activator Protein (AP)−1. Large-scale randomized, controlled clinical trials have demonstrated trifarotene to be safe, well tolerated, and efficacious in reducing both comedones and papules/pustules of acne. However, unlike all other retinoids, trifarotene is the first topical retinoid with rigorous clinical data on safety and efficacy in truncal acne. Data supporting use of trifarotene to manage acne are reviewed in this publication.
Being European, the nationalist way: Europe in the discourse of radical right parties
Authors: Beaudonnet Laurie , Hoyo Prohuber Henio
Published: March 2023

European radical right parties (RRPs) have recently experienced strong electoral success and have strengthened their positions within the European Parliament. While their Eurosceptic positions are well documented in the literature, the fact that most RRPs refer not only to their nations but to Europe in general in order to ground their nationalist visions remains understudied. We investigate this issue by analyzing the discourses of MEPs from 24 radical right parties in the 8th legislature of the European Parliament (2014–2019). Relying on a vast corpus (36,413 speeches) and using quantitative text analysis, this research sheds light on the various notions of Europe that are used by radical right MEPs. We find evidence of three visions of Europe: as a civilization; as an ethno-religious community; and as a liberal society. The use and preferences for these visions vary according to ideological positions, strategies and national contexts.
Community peer support among individuals living with spinal cord injury
Authors: McLeod Joy , Davis Christopher G.
Published: March 2023

Peer support is widely assumed to help individuals with spinal cord injury (SCI) adjust, yet the evidence is mixed. We propose that peer support may be more likely to promote adjustment when informal support is lacking. To test this hypothesis, 135 individuals living with SCI receiving peer support (46.7% female; Mage = 42.36, SD = 14.83) completed an online survey assessing aspects of and satisfaction with the peer support and family/friend support that they were receiving as well as measures of adjustment. Although those reporting receiving more peer support were not any better adjusted than those reporting less, individuals who were more satisfied with the peer support they received reported better adjustment. Moreover, the relation of satisfaction with peer support with depressive symptoms was dependent on the level of family/friend support. These findings suggest that peer support is most effective among those lacking support from family and friends.
Association between maternal socioeconomic status and breastfeeding: Results from the Japan environment and children’s study
Authors: Tanaka Rie , Tsuji Mayumi , Shimono Masayuki , Morokuma Seiichi , Morisaki Naho , Kusuhara Koichi , Kawamoto Toshihiro ,   Japan Environment and Children’s Study Group
Published: March 2023

Although breastfeeding has various benefits for mothers and children, there are several barriers to continuing breastfeeding practices. However, little is known about the relationship between breastfeeding in Japan and maternal socioeconomic circumstances. Based on data from the Japan Environment and Children’s Study ( n = 75,742), we evaluated maternal socioeconomic factors associated with breastfeeding 1 year after giving birth. Socioeconomic status (education, employment status, and household income), working hours, and breastfeeding were assessed using a self-administered questionnaire. After descriptive analysis, a logistic regression analysis was conducted with adjustments for age, educational level, employment status, and household income. Mothers with higher education and full-time homemakers were more likely to breastfeed one-year-old children. Mothers working long hours (both part-time and full-time) were less likely to breastfeed their one-year-old children. To improve breastfeeding among working mothers, it may be helpful to promote awareness of breastfeeding for every mother as well as to make the workplace environment conducive for working mothers to breastfeed.
The public-private decision for alcohol retail systems: Examining the economic, health, and social impacts of alternative systems in Finland
Authors: Sherk Adam , Stockwell Tim , Sorge Justin , Churchill Samuel , Angus Colin , Chikritzhs Tanya , Holmes John , Meier Petra , Naimi Timothy S. , Norström Thor , Ramstedt Mats , Simpura Jussi
Published: March 2023

Background: Organising alcohol retail systems with more or less public ownership has implications for health and the economy. The aim of the present study was to estimate the economic, health, and social impacts of alcohol use in Finland in 2018 (baseline), and in two alternative scenarios in which current partial public ownership of alcohol retail sales is either increased or fully privatised. Methods: Baseline alcohol-attributable harms and costs were estimated across five categories of death, disability, and criminal justice. Two alternate alcohol retail systems were defined as privately owned stores selling: (1) only low strength alcoholic beverages (public ownership scenario, similar to Sweden); or (2) all beverages (private ownership scenario). Policy analyses were conducted to estimate changes in alcohol use per capita. Health and economic impacts were modelled using administrative data and epidemiological modelling. Results: In Finland in 2018, alcohol use was estimated to be responsible for €1.51 billion (95% Uncertainty Estimates: €1.43 billion, €1.58 billion) in social cost, 3,846 deaths, and 270,652 criminal justice events. In the public ownership scenario, it was estimated that alcohol use would decline by 15.8% (11.8%, 19.7%) and social cost by €384.3 million (€189.5 million, €559.2 million). Full privatisation was associated with an increase in alcohol use of 9.0% (6.2%, 11.8%) and an increase in social cost of €289.7 million (€140.8 million, €439.5 million). Conclusion: The outcome from applying a novel analytical approach suggests that more public ownership of the alcohol retail system may lead to significant decreases in alcohol-caused death, disability, crime, and social costs. Conversely, full privatisation of the ownership model would lead to increased harm and costs.
Dynamic behaviors for the graphene nano/microelectromechanical system in a fractal space
Authors: Lv Guojuan
Published: March 2023

The microelectromechanical devices have triggered rocketing interest in various advanced technologies, that is, sensors, material science, and energy harvesting, and now the devices tend to a nanoscale size, making the technology much more attractive in both academic and industrial communities. This paper takes a graphene nano/microelectromechanical system as an example to study its dynamical property, which is the foundation for the optimal design and reliable operation. As the system is inextricably complex with singularity and zero conditions in a fractal space, the iteration perturbation method is used to obtain the periodic solution of the system. The results show clearly the low-frequency property of the system and pull-in instability; furthermore, the fractal dimension affects greatly the system’s dynamical property.
The analytical solution for the optimum voltage on regularizing electrodes of the open dynamically harmonized cell
Authors: Lioznov Anton , Nikolaev Evgeny
Published: March 2023

The Fourier transform ion cyclotron resonance method holds the lead in mass accuracy and resolving power among all other mass spectrometry methods. The dynamically harmonized cell is largely responsible for the supremacy. This cell has an ideal hyperbolic trapping potential after averaging over fast cyclotron motion. Recently we have introduced an open modification of the cell (especially useful with ultrahigh magnetic fields) and have found the analytical solution for the averaged potential inside it. The voltage on specific “regularizing” electrodes determines how close a potential is to the hyperbolic one. In this article, we find the optimal voltage on these “regularizing” electrodes analytically. This will assist with both further analysis and tuning of the trap after manufacturing.
Choosing (not) to be a chemistry teacher: Students’ negotiations of science identities at a research-intensive university
Authors: Nielsen Katia Bill , Madsen Lene Møller
Published: March 2023

This paper explores how the culture within a Danish university study programme affects students’ aspirations of becoming a high school chemistry teacher. We draw on ethnographic fieldwork and qualitative interviews to describe and analyse the culture of the programme. In the analysis we foreground the case of two students to understand their identity negotiations and changes in their teacher aspirations over time. By combining a ‘domains-of-power framework’ with the concept of ‘science identity’, we show how everyday practices formed a culture of power that positioned research in the centre and teaching as a less attractive career path. By unfolding the subtle mechanisms that together form a culture of power, which works both to include and exclude, we show the ways in which the two student’s aspirations for becoming high school chemistry teachers somewhat diminished over time. The study concludes that negotiating a science identity at a research-intensive university programme, makes it almost impossible to develop and keep an aspiration for becoming a high school teacher. To address the current and future shortage of science teachers across Europe, our findings underline the need for a more inclusive culture at the university to support science students’ diverse aspirations.
A novel acoustic emission sensor design and modeling method for monitoring the status of high-speed train bearings
Authors: Qi Hongyuan , Han Defu , Hou Dongming , Wang Cuiping
Published: March 2023

Acoustic emission (AE) technology is suitable for monitoring the status of high-speed train bearings owing to its high sensitivity and real-time dynamic monitoring capabilities. However, a complete theoretical model of the AE sensor, which is the core component of AE signal sensing equipment, has not yet been reported. The existing matching layer models do not account for wave attenuation in the matching layer. To address these shortcomings, we established a novel piezoelectric AE sensor design and modeling method. First, a rough contact model is established for piezoelectric ceramics, and the influence of roughness on size selection of piezoelectric ceramics is analyzed. Second, the sound intensity transmission coefficient (SITC) model of the matching layer is established considering the attenuation of AE waves, and the corresponding relationship between the attenuation coefficient and the optimum thickness of the matching layer is derived. Then a complete finite element (FE) model of an AE sensor is established, and the electroacoustic properties of the AE sensor are numerically simulated based on acoustic and piezoelectric coupling. Furthermore, AE sensors with different thicknesses of matching layers are constructed, and the validity of the mathematical model of the matching layer is verified through a lead-breaking experiment. Thereafter, a novel comprehensive performance evaluation index (CPEI) is designed through principal component analysis (PCA) based on hit parameters of AE sensors. Finally, the effectiveness and environmental adaptability of the AE sensor is verified by performance testing under complex conditions near an actual high-speed train line. The proposed method can provide a valuable theoretical framework for AE sensor design and status monitoring of high-speed train bearings.
Dielectric Behaviour of Crosslinked Polyether Resins during Moisture Absorption
Authors: Barton S.J. , Pritchard G. , Vaezi-Nejad S.M.
Published: March 2023

The moisture absorption characteristics of a novel crosslinkable polyether of relatively low polarity have been determined. The relative permittivity (dielectric constant) was found to be 3.2 at 1 kHz and 22°C. This value is compared with that obtained for other polymers. Changes in relative permittivity following exposure to moisture were compared with corresponding changes in the epoxy resin system Epikote® 828/MPD. The polyether absorbs much less water than the epoxy, and the relative permittivity changes less during exposure to moisture. A Clausius-Mossotti calculation has been used to examine the free state polarisability of the absorbed water. The analysis suggested that absorbed moisture plasticises the polyether, producing a greater change in overall dielectric response than could be attributed to the water alone. In contrast the increase observed in epoxy resins is less than expected from the mass of moisture absorbed.
Relation between Weight Changes and Bending Properties of GFRP Panel Immersed in Hot Water
Authors: Morii Tohru , Tanimoto Toshio , Hamada Hiroyuki , Maekawa Zen-ichiro , Hirano Takahiro , Kiyosumi Kenji
Published: March 2023

This study deals with the relation between weight changes and the bending properties of GFRP panels immersed in hot water. The GFRP panels used in this study were three kinds of randomly oriented E-glass fibre continuous strand mat reinforced unsaturated polyester resins. These panels were different in matrix resin and filler content. The water immersion tests were conducted at 80°C and the specimen weight before and after immersion was measured. After water immersion, three point bending tests were performed in order to evaluate the reduction in elastic modulus and strength. Weight changes were evaluated in two ways: the weight gain due to water absorption and the weight loss due to matrix dissolution. The water absorption kinetics was different from the typical Fickian diffusion behaviour, and a great amount of water penetration into the interface was associated with weight loss. Extensive weight loss due to matrix dissolution was caused by degradation at the fibre/matrix interface. The main causes of the modulus and strength reduction of GFRP immersed in water were clarified from the relation between weight changes and bending properties. The elastic modulus decreased with increasing water absorption, and eventually it became constant. The strength decreased linearly with the weight gain due to water absorption. The modulus and strength reductions were caused by the degradation of matrix resin due to water absorption-related processes, such as plasticisation and hydrolysis. However, the modulus reached a constant value in spite of a great amount of water absorption and this was caused by extensive degradation at the interface. The strength reduction observed along with matrix dissolution was caused by the reduction in the load bearing capacity of the fibre following interface breakdown.
The Processability, Electrical and Mechanical Properties of EMI Shielding ABS Composites
Authors: Ma Chen-Chi M. , Hu A.T. , Chen D.K.
Published: March 2023

Conducting composite materials based on acrylonitrile-butadiene-styrene (ABS) compounded with conductive fillers, i.e. carbon black and aluminium flakes were prepared. The effectiveness of such composite materials with regard to shielding against electromagnetic interference (EMI) was studied, and the relationships among electrical conductivity, processability and mechanical properties were explored. Effects of modifying the filler surface with coupling agents on various properties were also investigated.

Results show that the threshold for conductivity is about 5 vol% (20wt%) of conductive carbon black or 5 – 10 vol% (20–40wt%) of Al-flake in composites. The most optimised shielding effectiveness reaching 25dB and 30 dB when the ABS matrix contains 20 wt% of carbon black or 40 wt% of Al-flake. This performance is comparable with that of 1 mm thickness of copper sheet, or that of nickel coating. In addition, both mechanical and rheological properties of the conductive composites were studied.
The Analysis of Filled Polyphthalamide Composites after Hydrolytic Cleavage
Authors: Chaplin R.P. , Haken J.K. , Wei W.M.
Published: March 2023

The analysis of high performance polymers, because of their very properties of thermal stability and insolubility, will always be a difficult task. This analysis is even further complicated by the presence of fillers and other reinforcing materials. This paper describes a relatively simple procedure of preliminary hydrolytic fusion followed by chemical work-up and gas chromatography that enables the analysis of these materials to be successfully achieved. This success was shown by the analysis of a series of filled polyphthalamide samples.
Evaluation of Interfacial Strength for Glass Fibre Cloth Reinforced Plastics by First Fracture Detection
Authors: Morii Tohru , Tanimoto Toshio , Maekawa Zen-ichiro , Hamada Hiroyuki , Kiyoshumi Kenji , Ichihashi Hideki
Published: March 2023

This study is concerned with the detection of the initial stages of fracture of plain woven glass fibre cloth reinforced plastics. During the tensile test, the fracture process was recorded on video-tape. These images were analysed using an image analysing system in order to determine the brightness of each image. The initial fracture was identified by the change of brightness of a series of images as a result of debonding at the interface or because of matrix cracking in transverse fibre bundles. The interfacial strength was evaluated by the initial fracture stress. This technique can be applied to the estimation of the interfacial strength of woven fabric composites. The degradation behaviour of the interface was studied for the case of plain woven glass fibre cloth-reinforced vinyl ester resin, which had a strong interface, as a function of immersion in hot water (40, 60 and 80°C). The tensile strength was considerably affected by the water temperature, but the initial fracture stress was not.
The Application of Vibrational Spectroscopy to the Research and Development of Polymeric Materials: III. Instrumentation and Experimental Techniques in Raman Spectroscopy
Authors: Ellis G. , Marco C. , Fatou J.M. Gómez
Published: March 2023

Raman spectroscopy has developed significantly over the last twenty-five years, and its applications in the polymer field are growing on a daily basis, due to the considerable advances in Raman instrumentation, like for example the FT-Raman technique. This article is intended to provide a perspective on the use of conventional Raman spectroscopy, and present some of the more important developments.
Observations on New Proposals for Assessing how well Unsaturated Polyester Glass Laminates Withstand Petrochemical Environments
Authors: Ghotra Joginder S. , Pike Stephen
Published: March 2023

The chemical resistance of glass fibre laminates to petrochemical environments has to be evaluated before they can be adopted for use in petroleum storage tank applications. In this paper, the behaviour of isophthalic polyester glass laminates in the revised CEN test liquid, proposed in the draft CEN Standard, is compared with the corresponding behaviour in unleaded petrol, super unleaded petrol, diesel, and EEC Mixture (composition B). The chopped strand mat (CSM) laminates were tested under single-sided contact conditions with these liquids and with their vapours for 1000 hours at (50±1)°C, using the apparatus and procedure specified in the draft CEN Standard. Changes in the surface profile and percentage retention of flexural properties after exposure are reported.
Degradation Behaviour of Glass Fibre Mat Reinforced Polypropylene Immersed in Hot Water
Authors: Morii Tohru , Tanimoto Toshio , Hamada Hiroyuki , Maekawa Zen-ichiro
Published: March 2023

This paper deals with the degradation behaviour of randomly oriented continuous glass-fibre mat reinforced polypropylene (glass/PP) immersed in hot water. The weight changes and the bending properties were measured after immersion in water, and these were compared with the data for glass fibre reinforced unsaturated polyester (glass/UP). The weight changes of glass/PP were much less than those of glass/UP, and the fibre/matrix interface of glass/PP maintained its effective bonding even after immersion. As a result, the reduction in bending modulus of glass/PP was very slight. The bending strength of glass/PP decreased linearly against the net weight gain and the weight loss. The relationship between the bending strength and the weight loss was almost the same, independent of the materials used. It is suggested that the strength reduction in glass reinforced polypropylene was induced by the formation of microcracks, which also caused the weight loss.
Determination of the Damage Zone Size in Textile Fabric Reinforced Polypropylene Composites by Locating the Acoustic Emission
Authors: Czigany T. , Karger-Kocsis J.
Published: March 2023

The size of the damage zone was determined on modified compact tension (CT) specimens of model composites containing a single layer of different textile fabrics by locating the acoustic emission (AE) events during loading. Among the reinforcing fabrics both crimped woven (co-woven and/or hybrid clothes) and non-woven (swirl mat) structures were studied. The extent of the damage zone was linked to a circle or ellipse in which a given proportion of the AE events could be found. Its size was strongly underestimated when only the stress-whitened zone at the crack tip, resolved by light microscopy, was considered. It is therefore reasonable to distinguish a processing zone (stress-whitened region) within the damage one. The size of the damage zone depended upon the microstructure of the reinforcing fabric due to differences in the possible stress transfer, as expected.

It was also shown that the stress transfer and stress distribution capability of the fabrics strongly depend on their “wettability” by the matrix polymer; easily impregnable fabrics are loosely structured and/or hybridized ones.
Effects of Fibre Permeability on Moisture Diffusion Coefficients of Polymeric Composites
Authors: Aditya P.K. , Sinha P.K.
Published: March 2023

A single fibre composite model reinforced with a permeable fibre is used to evaluate the moisture diffusion coefficient analytically. Due to the fibre permeability, absorption of moisture takes place through both the fibre and the matrix. The diffusion paths around the fibre, due to their curved nature, are generated using the cubic spline theory. The diffusion paths through the permeable fibre are assumed to be a set of parallel lines. Diffusivities of such single fibre composites are computed at different values of relative fibre diffusivities. The relative fibre diffusivities corresponding to kevlar and jute fibres are considered separately to evaluate composite diffusivities. The diffusivities obtained for kevlar-epoxy and jute-epoxy single fibre models are found to be in good agreement with those available in the existing literature.
Preparation and Characterisation of “Cellulose/Ethylene Glycol Dimethacrylate/Acrylic Acid Cation Exchange Resins”
Authors: Abo-Shosha M.H. , Ibrahim N.A.
Published: March 2023

“Cellulose/ethylene glycol dimethacrylate/acrylic acid” cation exchange resins were prepared by bulk polymerisation of acrylic acid/ethylene glycol dimethacrylate (EGDMA) mixtures in presence of cellubse using ammonium peroxydisulphate as an initiator. Factors affecting the formation of the resins, such the concentration of each of ammonium peroxydisulphate, acrylic acid and EGDMA as well as polymerisation temperature were reported. Two cation exchange resins, of different capacities, were selected for characterisation by investigating their potentiometric titrations, water solubility, and swelling index as well as durability.
Predicting the Operating Characteristics and Play of Machine Sliding Bearings Made from Composite Materials
Authors: Levin Eng A.L. , Kacevman Eng
Published: March 2023

Polymer sliding materials are being used more and more in combinations of machine parts. The sliding properties and other characteristics of thermoplastics (acetal resins, polyamides) are temperature dependent. The main limitation of thermoplastic sliding bearings is the temperature. Calculation of the load capacity of thermoplastic sliding bearings should therefore form the basis for the thermal calculation of the sub-assembly, the purpose of which is to determine the operating temperature of the sub-assembly or (at a given permissible operating temperature) to determine the permissible operating parameters for the thermoplastic sliding bearing in the sub-assembly in question. Because of the low heat conduction and high thermal expansion coefficients of polymers, there are certain difficulties with heat dissipation through the bearing and the permissible tolerances when using thermoplastic sliding bearings.

On the basis of algorithms developed for the purpose, a program package has been developed to calculate the strength and stiffness of thermoplastic sliding bearings made from the most varied of materials. This presentation points out certain graphic dependences, determined with a plotter, of the initial dimensions on material properties and sub-assembly design.

Analysis of these relationships together with others determined during these machine experiments leads to the conclusion that the greatest efficiency can be achieved by simultaneously increasing the thermal conduction of the composite material by two to two and a half times and reducing the coefficient of friction to two thirds of the original value. By adding graphite fibres, the coefficient of thermal expansion can be reduced by 35%. This parameter has a decisive effect on the magnitude of the play in the sliding combination.
Zinc Acrylate and Other Solid Monomers as Crosslinking Agents for Unsaturated Polyesters*
Authors: Krolikowski Waclaw , Nowaczek Wieslawa , Penczek Piotr , Rudnik Ewa
Published: March 2023

The peroxide-initiated, copolymerisation of an unsaturated polyester with zinc acrylate, diallyl phthalate prepolymer and a solid vinyl ester resin was investigated. The curing was followed by means of gelation curves and differential scanning calorimetry. The studies showed that zinc acrylate has the highest reactivity.
Solvent Absorption by Carbon Fibre Reinforced PEEK Laminates
Authors: Pritchard Geoffrey , Randies Steven J.
Published: March 2023

The absorption of organic liquids by polyaryl ether-etherketone (PEEK) was investigated. Experiments with carbon fibre reinforced PEEK immersed in liquids of linear and cyclic molecules at 23°±2°C show that three important parameters (molecular size, shape, and polarity) have important effects on the diffusion rate. For the purposes of this study, using fibrous laminates rather than unreinforced polymers ensured matrix samples which were well-characterised and representative of practical materials with respect to crystallinity.

Special attention was directed to alkanes and alcohols. Three dimensional plots of weight absorption against hydrogen bonding capacity and the product of molar volume and solubility parameter mismatch are presented.

Implications for solvent resistance are suggested.