bluuebunny/crossref_metadata_2025 huggingface dataset:
Melan-A expression related to apoptosis of melanocytes in segmental and non-segmental vitiligo
Authors: Setyanto Boedhy , Kalim Handono , Poeranto Sri , Widasmara Dhelya
Published: October 2022

Background

Vitiligo is a progressive depigmentation of the skin with unclear etiology. Cell-mediated immunity has been suggested to play an important role in the pathogenesis of vitiligo’s progression. Melan-A has a high affinity for specific CD8+ T cells and is one of the critical markers for detecting damage to melanocytes. Our study aims to demonstrate the differences in Melan-A expression associated with apoptosis of melanocytes in patients with segmental vitiligo (SV) and those with non-segmental vitiligo (NSV).

Methods

A cross-sectional study with 64 patients diagnosed with vitiligo, of whom 33 had NSV and 31 had SV. Skin biopsy and direct immunofluorescence were used to examine Melan-A, and the TUNEL staining method was performed to examine melanocyte apoptosis in both groups. Group comparisons were conducted using appropriate statistical methods.

Results

Melan-A expression was significantly higher in the NSV group than in the SV group, and there was a significant difference between the two groups (p=0.001). The median of melanocyte apoptosis in the NSV group was relatively higher than in the SV group, and a significant difference was found between the two groups (p=0.001). The Spearman’s rank correlation test between Melan-A expression and melanocyte apoptosis in the NSV group was 0.767 (76.7%) and showed a significant relationship (p<0.05). The same test in the SV group was 0.583 (58.3%) and showed a significant relationship (p<0.05). In both groups, the higher the Melan-A expression, the higher the melanocyte apoptosis.

Conclusion

Melan-A expression and melanocyte apoptosis are positively correlated. Higher Melan-A expression and melanocyte apoptosis in NSV indicates more severe vitiligo disease compared to SV.
Effects of evidence-based clinical practice guidelines for breast cancer in health care quality improvements. A second systematic review.
Authors: Ramírez-Morera Anggie , Tristán Mario , Salazar-Vargas Jordan , Rivera-Chavarría Ana Leonor
Published: October 2022

Background: Traditionally, EB-CPGs have been believed to mainly improve the quality and consistency of health care, but this claim must be conclusively proven. We used the Donabedian three-dimensional model (structure, process, and patient outcomes) to assess improvements in the quality of medical care derived from implementing EB-CPGs. This study corresponds to the second systematic review carried out as a series of studies on different clinical issues that aim to evaluate the effectiveness of the application of the EB-CPG for improving the quality of care.

Methods: We followed the methods described by the Cochrane Handbook and presented a descriptive analysis because of the high heterogeneity found across the included studies. We searched the Cochrane Central Register of Controlled Trials, PubMed, and EBSCO Host databases, as well as the grey literature, between 1990 and April 2021. No language restrictions were applied. Only randomised clinical trials (RCTs) were selected.

Results: Of the total of 364 interventions included in the eleven RCTs evaluated, 11 (3%) were related to healthcare structure, 51 (14%) to the healthcare delivery process and 302 (83%) to patient outcomes. Regarding the impact of using the EB-CPGs, in 303 interventions (83%), there were no significant differences between the control and experimental groups. In 4 interventions (1%), the result favoured the control and intervention groups in 57 of the interventions (16%).

Conclusions: Our study showed that EB-CPGs slightly enhanced the quality of health care in the three dimensions described by Donabedian. Future RCTs should improve their design and methodological rigour by considering the certainty of the evidence supporting the EB-CPGs recommendations. In that context, broader analyses could be performed, having more concise hypotheses for further research.

Registration: PROSPERO CRD42020205594
Laboratory risk factors for mortality in severe and critical COVID-19 patients admitted to the ICU
Authors: Bestari Muhammad Garidya , Suharjo Tommy , Ayu Nuari Lulu , Hadi Faujan Abdul , Panjaitan Lucas Welfried , Bestari Muhammad Begawan
Published: October 2022

Background: Several studies have reported clinical characteristics and risk factors for predicting adverse outcomes in COVID-19.4–6 However, data exclusively from the ICU especially in the low- and middle-income countries (LMIC) remain lacking. This study aimed to explore risk factors associated with mortality based on laboratory parameters at hospital admission in severe and critical COVID-19 patients admitted to the ICU.

Methods: This study is a retrospective cohort study. Data from the electronic medical records were collected retrospectively from all severe and critical COVID-19 patients requiring ICU admission in two designated COVID-19 hospitals in Jakarta, Indonesia. A multivariate logistic regression analysis was used to identify the predictors associated with ICU mortality. The model performance was evaluated by the area under curve (AUC) from the receiver operating characteristic (ROC) analysis.

Results: There were 334 patients admitted to the ICU with COVID-19 included in the statistical analysis. The ICU mortality rate was 75.1%, with 251 patients died in the hospital. Independent risk factors associated mortality including white blood cell count >13.9 x109/L (OR=2.41; 95% CI, 1.15-5.06, p=0.02), neutrophil to lymphocyte ratio >10.7 (OR=2.20; 95% CI, 1.20 – 4.03, p=0.011), and creatinine >0.8 mg/dL (OR=3.55; 95% CI, 2.05 – 6.17, p<0.001). The model yielded an AUC of 0.72 (95% CI, 0.659-0.780, p<0.0001) for predicting ICU mortality in severe and critical COVID-19 patients.

Conclusions: White blood cell, neutrophil to lymphocyte ratio, and serum creatinine on hospital admission are significant predictors of mortality in severe and critical COVID-19 patients admitted to the ICU. The ICU mortality rate during the second wave of the pandemic in this study was high.
The ‘Public Order’ Parachute in Combating Racism and Xenophobia
Authors: Ginter Carri , Soo Anneli
Published: October 2022

The European Commission has initiated infringement proceedings against virtually half of the Member States, accusing many of, inter alia, failing to take the necessary measures to ensure that racist and xenophobic hate crimes are effectively criminalised. The article looks at the right of a Member State to limit prosecution for incitement of violence or hatred to acts that are carried out in a manner likely to disturb the public order. The authors argue that application of the ‘risk to public order’ criterion if interpreted appropriately, will in most cases reduce the threat of ‘taking it too far’. They argue also that there is a risk of confusion between ‘public order’ and ‘public nuisance’, due to the national criminal courts being more familiar with the latter. This could lead to unreasonably loose application of criminal punishments and pose a risk breaching the nullum crimen nulla poena sine lege certa principle. Perhaps because of having suffered censorship and absence of fundamental rights under the Soviet Union, Estonian society voices strong concerns about criminalisation of hate speech. In the authors’ view, these concerns may be reduced by narrow interpretation of the ‘risk to public order’ notion.
A TEXTILE ARCHITECTURE-BASED DISCRETE MODELING APPROACH FOR FABRIC DRAPING SIMULATIONS
Authors: 10.12783/asc37/36368 WEI QINGXUAN , ZHANG DIANYUN
Published: October 2022

Adoption of lightweight composites for structural components is transforming the transportation industry in pursuit of improved performance and better fuel economy. In Liquid Composite Molding (LCM), dry fabric deformation in the draping process gains lots of attention as it affects the fiber orientation, leading to variations in fabric permeability and the resulting final quality of the product due to the change in infusion and curing processes. The lack of robust modeling tools makes the composite manufacturers heavily reliant on trial-and-error approaches to minimize part variability, resulting in high manufacturing costs and limiting innovations for new process and part designs. The current study develops a modeling approach to predict the deformation for dry fabric. In the model, fabric is made of interlacing virtual fiber tows which are represented by Timoshenko beams joint by translational and rotational springs. Dashpots at intersections are used to capture energy dissipation. The proposed model features the simplicity and efficiency in the prediction of shear angle when fabric is subject to 3-dimensional loading. Another highlight of this study is the consideration of characterized relaxation behavior of fabric subject to in-plane shear loading. Cantilever beam bending tests and picture frame tests were carried out to characterize material properties, geometric characteristics, spring stiffness, and damping coefficients. The proposed model was applied to a hemisphere draping model implemented in Abaqus to demonstrate the predictive capability.
AN EFFICIENT NUMERICAL APPROACH TO EVALUATE PROCESS-INDUCED FREE-EDGE STRESSES IN LAMINATED COMPOSITES
Authors: ZAPPINO ENRICO , ZOBEIRY NAVID , PETROLO MARCO
Published: October 2022

This paper presents an advanced modeling approach to predict process-induced residual stresses at the free-edge of laminated structures. The numerical model is based on the Carrera Unified Formulation, a numerical tool that allows any kinematic model to be considered without an ad hoc implementation. A layer-wise kinematic model has been adopted to detect the through-the-thickness distributions of transversal stresses. The process's evolution of the material properties is obtained by the RAVEN ® software. A cure hardening instantaneously linear elastic (CHILE) constitutive model was adopted. Peeling and transverse shear stress distributions along free-edges were computed and proved to be very high and localized.
MACHINE LEARNING FOR STRENGTH AND DAMAGE PREDICTION OF ADHESIVE JOINTS
Authors: KAISER ISAIAH , RICHARDS NATALIE , TAN K. T.
Published: October 2022

In this study, machine learning (ML), a subdivision of artificial intelligence (AI), is implemented to study the mechanical behavior of adhesive single-lap joints (SLJs) subjected to tensile loading. The experimental data for training and testing the ML models are compiled from peer-reviewed journal papers to eliminate bias and increase the diversity within the data. The dataset is comprised of eight continuous SLJ parameters, which are used to predict the SLJ damage mode and failure strength. To accomplish this, regression and classification models are built using deep neural networks (DNN) and random forests (RF). Finite element (FE) modeling is conducted, and the performance is compared with the accuracy of the regression ML models. Results show ML models were able to predict strength with higher accuracy than FE modeling. Furthermore, both DNN and RF classified damage mode accurately without failure criteria, exposing limitations within FE modeling. As a result, this study introduces the use of ML for strength and damage mode prediction of adhesive SLJ, providing insights into their mechanical behavior, revealing hidden property performance patterns, and enhancing predictability.
INVESTIGATING THE INFLUENCE OF NANOPARTICLE SIZE AND ORIENTATION ON FAILURE IN NOTCHED EPOXY NANOCOMPOSITES USING THE ATOMISTIC J-INTEGRAL
Authors: ROY SAMIT , SOHAIL TANVIR
Published: October 2022

The goal of this paper is to (a) investigate the validity of using continuum-based linear elastic fracture mechanics (LEFM) methodology to model fracture processes at the "discrete" atomic scale and (b) investigate the impact of nanographene platelet size on the rupture strength of an edge-cracked polymer block. EPON 862 epoxy polymer with a cross-link density of 85 percent was selected for this study. Furthermore, an atomistic J-integral is used as a nanoscale fracture metric to explore flaw-tolerance at the nanoscale, which several other studies have reported, and to build a methodology to evaluate and predict the material's initiation fracture toughness. For this purpose, five different molecular dynamics (MD) models of edge notched specimens that are similar to Compact Tension (CT) specimens were developed, each with a different size of graphene nanoplatelet (GNP) and different orientations, and they were all embedded in EPON 862 epoxy polymer with 85 percent cross-link density. All simulations in this work are performed using the molecular dynamics software LAMMPS and the bond order based ReaxFF potential available in LAMMPS. Significant deviation of peak Jintegral values from LEFM is detected at crack lengths below a critical threshold crack length. GNP size and orientation significantly affect far-field stress vs. strain plots and near-tip stress-fields. The atomistic J integral plots also revealed that our computational methodology is robust enough to capture weak singularity at the subcritical crack-tip, and that J vs. K data approximately obeys the quadratic relationship predicated by LEFM even at the nanoscale.
EXPERIMENTAL AND NUMERICAL EVALUATION OF LIGHTNING-INDUCED DEGRADATION OF FASTENED COMPOSITE SYSTEMS
Authors: MICHAEL LOUISA , TUCK DEREK R. , BOETTCHER PHILIPP A. , JUSTUSSON BRIAN P. , CARPENTER BRIAN A.
Published: October 2022

Aerospace composite laminate construction is widely used in various airframe components. Composite structures are often joined with other structure and substructure via fasteners that are inevitably exposed to lightning strike currents. The interaction of a lightning strike with a fastener can lead, through complex electrical, mechanical, and thermochemical processes, to the degradation of the strength of the fastened structure. Although degradation can often be seen on the surface as damage via paint discoloration, surface ablation, or surface delamination, a larger subsurface volume of material might be affected by the electrical current and thermo-chemical processes resulting in a heat affected zone and multi-planar delamination. Together, these effects have the potential to degrade the structural performance of the joint. In this work, a series of electro-mechanical tests is performed in order to evaluate the effect of lightning strikes of varying amplitudes on structural composite. The experimental methodology includes subjecting a single-fastener aerospace-composite lap joint to scaled Awaveform electric current pulses to determine the combined electromagnetic and structural effect on the system. Following the electrical test, the tested articles undergo a non-destructive inspection to quantify the extent of the damage, from which the relation between heat-affected zones extents and current levels is given. Finally, electrically-tested articles undergo a bearing test and the structural effect of the lightning strike on the structural properties of the fastened system is determined and implications on composite structural performance is assessed.
INVESTIGATING THE EFFECTS OF CURE PRESSURE ON TOOL-PART INTERACTION AND PROCESS-INDUCED DEFORMATIONS IN COMPOSITES
Authors: SCHOENHOLZ CALEB , MOOMAW JOANN , ZOBEIRY NAVID
Published: October 2022

The interaction between a tool and part during composites manufacturing may significantly contribute to the formation of residual stresses and process-induced deformations (PIDs). High levels of uncertainty are often associated with tool-part interaction and resulting PIDs due to the complex underlying physics, and variabilities and uncertaintieis in processing. During the assembly of aerospace composite structures, PIDs may create significant geometry mismatches and lead to a loss of mechanical performance. Aerospace manufacturers commonly use costly and timeconsuming techniques such as shimming to compensate for PIDs and meet process specification requirements. Although process simulation tools have evolved significantly in recent years to enable mitigation of PIDs via tool geometry compensation, in practice, they are not implemented often due to challenges associated with the characterization and calibration of numerical models. One such challenge is accurately measuring the degree of tool-part interaction and interfacial stresses during processing cycles. This paper presents a custom-built test fixture to directly measure tool-part interfacial stress development during processing of composites. The experimental setup is installed in a Dynamic Mechanical Analyzer (DMA) for in-situ measurement of tool-part interfacial stresses. The technique allows for the evaluation of the effects of process parameters, including pressure, temperature, lay-up, and tool surface condition. In this study, tool-part stress development was characterized as a function of the applied pressure for Toray T800S/3900-2 laminates cured on steel tools treated with Frekote release agent. The characterized stresses were then validated by measuring warpages of long and symmetric laminates cured on flat steel tools using different pressures similar to DMA tests. Results demonstrated that cure pressure significantly impacts the multi-physics interactions between fibers, resin, interply tougheners, and the tool surface throughout a cure cycle. The results of this paper can be used to expand the current understanding of tool-part interaction and potentially mitigate PIDs in composites processing.
MESOSCALE ANALYSIS OF TRANSLAMINAR FRACTURE IN THIN-PLY LAMINATES
Authors: AHMADVASHAGHBASH SINA , MEHDIKHANI MAHOOR , SWOLFS YENTL
Published: October 2022

Translaminar fracture toughness is a key property that determines the notch sensitivity and the damage tolerance of fibre-reinforced composites. By establishing a novel downscaled compact tension specimen configuration, designed for 4D synchrotron radiation computed tomography, a comprehensive perception of developed failure mechanisms can be attained. In this study, first, an initial finite element model, based on limited literature data for a compact tension of a [90/0]8s T300/913 carbon-epoxy laminate [1] is developed. Next, the cohesive law parameters between 0°/0° plies in a [902/0/902/0/902/0/902] thinply HS40/736LT laminate are directly extracted from in-situ synchrotron radiation computed tomograms of miniaturized compact tension specimens. The interlaminar (90°/90°) parameters are obtained from double cantilever beam test results on a similar material system. To accurately predict the 𝑅-curve, the crack extension and crack opening displacements, in both 90° and 0° plies, were captured in a multi-linear cohesive law. Consequently, in the proposed finite element approach, two distinct cohesive surface definitions are assigned to the fracture plane. The numerical results confirm the lagging crack fronts in 0° plies.
EFFECT OF MANUFACTURING DEFECTS ON COMPOSITE ENERGY ABSORBERS: EXPERIMENTAL ANALYSIS
Authors: BHASIN AKHIL , KESHAVANARAYANA SURESH RAJU , MAICHAN TANAT , RAMDIAL HOOLOOMANN , GOMEZ LUIS MANUEL , OLIVARES GERARDO
Published: October 2022

Energy absorbers manufactured using reinforced composite materials absorb energy by undergoing a complex combination of failure modes such as matrix cracking, fiber fracture, delamination, sub-laminate bending, and fiber-matrix debonding. The presence of defects could undermine the load-carrying capabilities of these energy absorbers. In the current investigation, the effect of manufacturing defects on energy absorption capabilities and damage evolution of two different geometries, corrugated beams and cchannel stanchions, has been presented. The manufacturing defects investigated, introduced during specimen fabrication, include out-of-plane fiber waviness/wrinkling and delamination. Two different material systems and two different stacking sequences have been evaluated for each energy absorber type. Three-dimensional Digital Image Correlation (DIC) provides a comparison of damage evolution of pristine specimens and specimens with manufacturing defects.
MECHANICAL CHARACTERIZATION OF 8HS S-2 GLASS/SC15 COMPOSITES FOR MAT162 APPLICATIONS
Authors: AYTEN ALI I. , ALI MOLLA A. , HAQUE BAZLE Z. (GAMA)
Published: October 2022

MAT162 is a composite material model, which has been used for simulating ratedependent progressive damage behavior of composite materials under high velocity impact applications such as ballistic penetration and perforation. A limited number of material systems, e.g., (i) unidirectional (UD) S-2 Glass/SC15, (ii) plain weave (PW) S-2 Glass/SC15, (iii) PW S-2 Glass/Phenolic, and (iv) PW E-Glass/Phenolic composites have been characterized for MAT162 material properties and modeling parameters in the literature. This material model needs 37 material properties and parameters to present rate-dependent progressive damage occurred in structure. For this purpose, a series of mechanical characterization tests and model validating experiments and computational simulations need to be performed. In this study, 8HS weave S-2 glass fabric reinforced with SC15 epoxy matrix composites has been characterized for MAT162 applications. Composite laminates of various thickness have been manufactured by hand lay-up method, cured at room temperature (RT) under vacuum and post-cured in an oven under vacuum. In-plane tension, quasistatic punch shear test (QS-PST), quasi-static punch crush test (QS-PCT), three-point bending, short beam shear and model validating low velocity impact (LVI) experiments were performed to determine the material properties and modeling parameters of 8HS S-2 glass/SC15 composites. Experimental damage modes and mechanisms have been quantified and used as input in validating the LS-DYNA computational models.
DYNAMIC BEHAVIOR OF FIBER-REINFORCED COMPOSITES UNDER TRIAXIAL COMPRESSION
Authors: GAO JINLING , KIM GARAM , CHEN WEINONG
Published: October 2022

Fiber-reinforced composites (FRCs) under transverse impact by bullets are demonstrated to be subjected to the multi-axial stress state. This study presents the dynamic behavior of unidirectional composites at confining pressure. An S-2 glass/SC- 15 composite laminate was manufactured by using a resin injection method and then sectioned into small cylindrical specimens. Optical microscopy was utilized for specimen characterization and the fiber volume fraction was measured. Dynamic experiments were conducted by using a conventional Kolsky compression bar modified by adding a radial and axial confining chamber. Prior to the dynamic loading, hydraulic pressure up to 50 MPa was applied to the two chambers simultaneously. The radial chamber enclosed the cylindrical composite specimen and applied the radial confining pressure. On the other hand, the axial chamber was added at the free end of the transmission bar, providing the axial portion of the hydrostatic pressure to the specimen. Once the triaxial confinement was achieved, a striker impacted the incident bar to apply a dynamic compressive load to the specimen. The specimens’ dynamic responses were compared with that without confining pressure. It is found that the peak strength of the composite increased as the confining pressure increased.
CARBON NANOTUBE REINFORCED-EPOXY BASED ADHESIVES: CORRELATIONS BETWEEN FRACTURE MORPHOLOGY AND CHEMICAL FUNCTIONAL CHANGES
Authors: LEÃO SUCHILLA G. , REIS MILVIA O. DOS , MONTEIRO ELVIS C. , AVILA ANTONIO F.
Published: October 2022

This paper addresses the experimental correlations between failure mode morphologies and the chemical changes inside an epoxy-based adhesive nanomodified by carbon nanotubes. This “special” nanocomposite is under a combined loading. i.e., shear and peel stresses, commonly encountered into single lap joints under tension. An increase in intensity on FTIR spectra on chemical functional at wavenumbers ranges 750-835 cm-1, 1170-1250 cm-1 and 1450-1610 cm-1 are related to the ductile-like fracture morphology due to more molecular mobility. At meanwhile, the increase in intensity at 2950-3350 cm-1 wavenumber range is linked to brittle-like morphology fracture. The cohesive failure is associated to the ductile-like failure morphology, while the adhesive failure is related to brittle-like morphology fracture.
CELLULOSE NANOFIBERS (CNF) REINFORCED CARBON FIBER/EPOXY MATRIX COMPOSITE WITH HIGHER MECHANICAL PROPERTIES
Authors: BHAGANAGAR SIDDHARTH , BISWAS PIAS KUMAR , AGARWAL MANGILAL , DALIR HAMID
Published: October 2022

The effect of the Cellulose Nanofibers (CNF) compositions, their morphology on carbon fiber, and subsequent mechanical properties have been explored in this work. The CNF composite nanofiber networks were introduced as interleave layers to improve the interlaminar shear strength (ILSS) of an epoxy/carbon fiber laminate composite. Dry carbon fiber was coated by different volume fractions of CNF (0.6wt%, 0.8wt%, 1wt%) through the sonication process. The CNFs volume fraction and delamination properties of enhanced carbon fiber reinforced polymer (CFRP) laminates have been studied. It is shown that when the dry carbon fiber was treated with CNF, the laminate shows greater mechanical strength in certain cases. The application of CNF composite nanofiber networks as an interleaved layer in an epoxy/carbon laminate increased the delamination resistance of the ILSS in both 0.8wt% and 1wt% CNF by 27.2% and 12.4% respectively, while compared to the neat control sample. This result suggests that CNF could enhance the delamination resistance of an epoxy/carbon laminate undergoing stress and deformation. This result is attributed to crack path modification, and load energy absorption by higher modulus CNFs reinforced nanofibers interleave in the laminate resulting in a higher shear modulus to the networks.
PERFORMANCE IMPACTS OF 3D SLICERS ON ADDITIVELY MANUFACTURED COMPOSITE JOINTS
Authors: GEISE LUKE , ABBOTT ANDREW , RAPKING DANIEL , FLORES MARK
Published: October 2022

Topology optimization (TO) combined with composites additive manufacturing (AM) enables design of skeletal structures that present opportunities for weight savings in aerospace structures. Of critical importance in these structures are intersecting elements, or joints, that, if improperly designed, can be origin points for structural failure. This study simplifies TO joints to 4-member AM x-joints and investigates the performance impact of the slicing software and infill pattern on the joint. A mechanical test method was developed to evaluate x-joints in a two phase study. Phase I leveraged fused filament fabrication (FFF) of neat PLA in a screening study that sampled the available design space. Using the data collected in phase I, phase II produced additively manufactured composites via direct ink writing (DIW). Ultimately, slicer and infill patterns were recommended for the creation of AM composite joints that demonstrate high stiffness, repeatable maximum stress, and progressive damage. Preliminary mosaic style numerical simulations which accurately predict damage and material response were also completed.
DESIGN OF COMPOSITE DOUBLE-SLAB RADAR ABSORBING STRUCTURES USING FORWARD, INVERSE, AND TANDEM NEURAL NETWORKS
Authors: NIELSEN DEVIN , LEE JUHYEONG , NAM YOUNG-WOO
Published: October 2022

The survivability and mission of a military aircraft is often designed with minimum radar cross section (RCS) to ensure its long-term operation and maintainability. To reduce aircraft’s RCS, a specially formulated Radar Absorbing Structures (RAS) is primarily applied to its external skins. A Ni-coated glass/epoxy composite is a recent RAS material system designed for decreasing the RCS for the X-band (8.2 – 12.4 GHz), while maintaining efficient and reliable structural performance to function as the skin of an aircraft. Experimentally measured and computationally predicted radar responses (i.e., return loss responses in specific frequency ranges) of multi-layered RASs are expensive and labor-intensive. Solving their inverse problems for optimal RAS design is also challenging due to their complex configuration and physical phenomena. An artificial neural network (ANN) is a machine learning method that uses existing data from experimental results and validated models (i.e., transfer learning) to predict complex behavior. Training an ANN can be computationally expensive; however, training is a one-time cost. In this work, three different Three ANN models are presented for designing dual slab Ni-coated glass/epoxy composite RASs: (1) the feedforward neural network (FNN) model, (2) the inverse neural network (INN) model – an inverse network, which maintains a parallel structure to the FNN model, and (3) the tandem neural network (TNN) model – an alternative to the INN model which uses a pre-trained FNN in the training process. The FNN model takes the thicknesses of dual slab RASs to predict their returns loss in the X-band range. The INN model solves the inverse problem for the FNN model. The TNN model is established with a pretrained FNN to train an INN that exactly reverses the operation done in the FNN rather than solving the inverse problem independently. These ANN models will assist in reducing the time and cost for designing dual slab (and further extension to multi-layered) RASs.
LIGHTWEIGHT APPROACH TO SMC COMPOSITES: NANOCELLULOSE COATED GLASS FIBER FABRIC
Authors: BIEDERMAN ERIC , BELLONIA ATHINA , SHARITNIA SHADI , JARRAHBASHI DORRIN , ASADI AMIR , KALAITZIDOU KYRIAKI
Published: October 2022

The focus of this study is to investigate how to lightweight SMC composites for automotive applications without compromising their performance. This is accomplished by replacing, at least partially, the heaviest materials such as the glass fibers (GF) or calcium carbonate (CaCO3) with nanocellulose or nanoclays. In addition, the chopped glass fibers are replaced by glass fabric in order to better control the location and orientation of the glass fiber reinforcement and thus engineer the mechanical properties. Unsaturated polyester resin (UPR) is used as the resin, and a pilot scale sheet molding compounds (SMC) is used to make the SMC. The composites are made by stacking plies of SMC layers in a mold, after appropriate conditioning of the SMC, and compression molding. The properties of interest are the tensile and flexural modulus and strength according to the corresponding ASTM standards and the density of the composites. The void content is also determined using acid digestion and scanning electron microscopy. The main goal is to replace traditional chopped glass fibers (GF) used in SMC with unidirectional glass fabric coated with cellulose nanocrystals (CNC). The reasoning is to enhance properties with a better UPR/GF interface and controlled fiber orientation while reducing density. The glass fiber fabric is coated with nanocellulose using a scalable spraying technique that leads to homogeneous coatings. The four different glass fiber fabrics that were used in this study vary in CNC coating amount. To understand the effect of the nanocellulose, the glass fiber content of all composite formulations was kept constant at about 30 vol%. In addition, to determine the mechanical properties of the composites, the viscosity was verified for all formulations to ensure processability using the SMC pilot line. SEM micrographs show the quality of the CNC coating on the glass fiber fabric. Water uptake of all composites was also determined. The expected results address design, processing, and testing challenges, and successes and failures. The question to be addressed is whether CNC coated fabric is significantly advantageous for SMC compared to randomly oriented, chopped GF.
EFFECTS OF MAGNETIC ALIGNMENT AND CNT AGGLOMERATION ON REINFORCING FRACTURE TOUGHNESS OF POLYMERS
Authors: BRANCO RICARDO BRAGA NOGUEIRA , OYAMA KOHEI , YAMAMOTO NAMIKO
Published: October 2022

Reinforcing composite materials with carbon nanotubes (CNTs) has the potential to improve mechanical and/or multifunctional properties due to their nano-size. Research has been done on using CNTs to reinforce the interlaminar strength of carbon fiber reinforced composites (CFRPs), but most of the previous work is about randomly oriented carbon nanotubes. Currently, one of the main challenges regarding CNT integration into polymers is mitigating their agglomeration and controlling their dispersion in the polymer matrix. By aligning CNTs with an external field, more tailored structure control can be achieved, and a better understanding of how CNT agglomeration and dispersion relate to external field application and CNT concentration is needed. In this work, we studied the effects of magnetic field magnitude, CNT concentration, and matrix viscosity on CNT agglomeration and morphology. We measured the fracture toughness reinforcement of epoxy-CNT nanocomposites at various CNT concentrations (0.1 vol.% and 0.5 vol.%), magnetic field magnitudes (no field, 180 G, and 300 G), and matrix viscosities (older epoxy-hardener system with higher viscosity and newer epoxy-hardener system with lower viscosity). Our results demonstrated that aligning CNTs with a magnetic field can lead to extra reinforcement when compared to using randomly oriented CNTs if the field magnitude, CNT concentration, and matrix viscosity are selected accordingly. The maximum fracture toughness reinforcement achieved with the higher viscosity epoxy-hardener system (~72%) was with 0.5 vol.% of CNTs with a 180 G field, whereas the maximum reinforcement with the lower viscosity epoxy-hardener system (~62%) was observed for the samples fabricated with 0.1 vol.% of randomly oriented CNTs. COMSOL simulations were also conducted to understand the behavior of CNT agglomeration and alignment at different field magnitudes and CNT concentrations, and were compared with the experimental results. To maximize CNT reinforcement, more work needs to be conducted to address the challenge of CNT agglomeration and dispersion control in a polymer matrix, such as a more in-depth study of how different field magnitudes affect fracture toughness improvement and new methods to improve CNT dispersion.
THE EFFECT OF TWO-WAY SHAPE MEMORY ON THE HEALING OF POLY (ETHYLENE-CO-METHACRYLIC ACID) AND POLYBUTADIENE BLEND
Authors: IGBOKWE EMMANUEL , IBEKWE SAMUEL , MENSAH PATRICK , LI GUOGIANG , DAVID CHINMEN
Published: October 2022

Development in self-healing materials and smart composites has continuously improved for many decades and has given rise to many real-life applications with implications for engineering materials, structures, and human beings who rely on these technological innovations to further human endeavor. This study involves the use of intrinsic selfhealing ability of poly (ethylene-co-methacrylic acid) thermoplastic, known by its commercial name as Surlyn 9520©, and combined two-way shape memory effect with Di cumyl-peroxide (DCP) cross-linked polybutadiene elastomer to achieve crack narrowing and closure with subsequent healing of the polymer blend surface. The simple batch mixing process resulted in an immiscible yet compatible blend, determined by two distinct melting peaks from DSC characterization and FTIR spectroscopy analysis. Different blends ratios of 80/20, 70/30, 60/40, 50/50 were investigated and characterized. However, the 80/20 blend was chosen to demonstrate the significance of the two-way shape memory effect, where a material experiences elongation upon cooling and contraction upon heating to achieve crack closure and effectual healing. Two sets of samples were studied; control Sample known as 2A and 2B samples were one time programmed to about 300% strain. Self-healing, which is a function of the poly(ethylene-co-methacrylic) acid component of the blend, was established for both sets of specimens. The flexural properties from three-point bending test indicate that although both sets of samples achieved good healing efficiencies, the 2B programmed samples displayed better healing efficiencies than the control by 30%.
DESIGN AND TESTING OF AN ADDITIVELY MANUFACTURED SELF-SENSING COMPOSITE MATERIAL
Authors: WERTZ JOHN , TALLMAN TYLER , CHERRY MATT , HANEY RONEISHA , GROO LORIANNE
Published: October 2022

The growing trend towards limited-life aircraft brings a host of new challenges for nondestructive evaluation of their condition. One approach is to use materials with integrated sensing which provide low-to-medium fidelity information for rapid decision-making. In this work, electrical impedance tomography is applied to additively manufactured polymer-matrix composite materials with leads and electrodes directly printed into the material volume. A computational study is presented that shows volumetric resolution of surface and sub-surface damage with embedded electrodes.
EFFECTS OF TRANSVERSE COMPRESSION ON THE STRUCTURE AND AXIAL PROPERTIES OF POLYETHYLENE: A MOLECULAR SIMULATION STUDY
Authors: CHOWDHURY SANJIB C. , LONGORIA TIMOTHY , DEITZEL JOSEPH , GILLESPIE, JR. JOHN W.
Published: October 2022

In this paper, the effects of transverse pressure on the structure and axial tensile properties of polyethylene (PE) crystals have been studied using all-atom molecular dynamics (MD) simulations. In the MD simulations, the inter-atomic interaction is modeled by the modified adaptive intermolecular reactive bond order (AIREBO-M) force field. Hugoniot equation of state of the PE crystal is developed using isotropic compression simulations. To investigate the transverse pressure effects, both the pristine and defective crystals (i.e., crystal with chain ends, equivalent to fibril) are subjected to axial tensile loading at different levels of transverse pressure from 0.0 to 20 GPa, and the tensile properties are predicted as functions of transverse pressure. Simulation results show that the transverse pressure significantly affects the tensile properties of PE especially for the fibril models by intensifying the inter-molecular interactions and changing the damage modes from chain end slippage to chain scission. At the highest level of transverse pressure, the improvement in modulus is predicted to increase by 50% for both pristine and defective crystal. Tensile strength is predicted to increase by 44% and 290% for the pristine and defective crystals, respectively These predictions provide insight into the response of UHMWPE subjected to high velocity impact where strain rates and transverse pressure loading are orders of magnitude greater than quasi-static loading at ambient pressure conditions.
EFFECTS OF EXTRUSION RATE AND POST-ANNEALING ON MECHANICAL PROPERTIES AND PRINTING QUALITY OF ADDITIVELY MANUFACTURED CARBON FIBER REINFORCED POLYETHERKETONEKETONE (PEEK) PARTS
Authors: MARTINEZ JIMENA , YAP TIMOTHY , TEHRANI MEHRAN
Published: October 2022

The development of high-temperature fused filament fabrication (FFF) 3D printers has enabled the additive manufacturing (AM) of polymers and composites with relatively high thermomechanical properties. Among them is polyetherketoneketone (PEKK) reinforced with short carbon fibers (CF-PEKK). PEKK is a high-performance thermoplastic that belongs to the polyaryletherketone (PAEK) polymer family with excellent mechanical properties. In particular, it offers a glass transition temperature of ~140°C, a relatively high modulus that can be readily enhanced by carbon fiber addition, and specific strength comparable to aluminum alloys. Therefore, there is a growing interest in using CF-PEKK to replace metal parts. Low dimensional accuracy and resolution, high porosity, and poor inter-layer strength [1-3] have limited FFF parts to rapid prototyping and non-structural applications. This paper aims to investigate extrusion rate, a printing parameter, and post-annealing as a potential solution to reducing porosity and enhancing inter-layer strength in CF-PEKK printed parts. A 5% increase in the theoretical extrusion multiplier (EM) resulted in a 1.6% reduction of void content accompanied by a 30% improvement in the inter-layer tensile strength of CFPEKK coupons. The impacts of extrusion rate and post-annealing (in a salt-packed container) on the printing quality of CF-PEKK parts are also determined. No significant structural or dimensional changes were detected with the higher extrusion rate or annealing in salt. This paper provides a new understanding of mechanical properties, processing, printability of CF-PEKK, and their AM challenges.
IMPACT OF NONUNIFORM FIBER ARRANGEMENTS ON SIMULATED COMPOSITE TRANSVERSE-TENSILE STRENGTH
Authors: HUSSEINI JAMAL F. , STAPLETON SCOTT E. , PINEDA EVAN J.
Published: October 2022

Micromechanical models of fiber reinforced composites are becoming a main area of research because damage and failure often initiates at small scales. Microscale features such as fiber clusters and matrix pockets are thought to impact failure because they introduce localized stress concentrations and low stiffness regions where cracks propagate easily. The challenge in modelling these features is due to the fidelity required to capture local fiber to fiber interactions. In this study, a generator was used which can tailor microstructures to create fiber clusters and matrix pockets, while still maintaining a degree of randomness. Fiber clusters and matrix pockets were identified by using an algorithm which sorted and filtered neighboring fiber triads. Descriptors were calculated for each microstructure based on the area and number of clusters, as well as local volume fraction distribution. Microstructures were loaded using a reducedorder model which calculated strength and stiffness. Results show the relationship between generator inputs and descriptor outputs, as well as strength and stiffness.
Konfederacje w prawie ustrojowym Rzeczypospolitej
Authors: Makiłła Dariusz
Published: October 2022

Confederations were a crucial part of the Commonwealth’s social life, deeply rooted in the political awareness of the nobility. They were formed in special situations requiring extraordinary actions. The present paper briefly characterizes the variety of forms taken by confederations and their evolution over the years. In addition, the article aims to present the legislative issues of the functioning of confederations and to clarify the dualistic nature of the described phenomenon – both legal and non-legal, as well as their functioning as an element of regime during emergency situations. The analysis focuses on the operating rules of military confederations, those formed by the king and those established during interregnum, while paying a special attention to the issue of a new ruler’s election. In the case of each form of the nobility unions, the paper presents a wide range of consequences they entailed – political as well as social and economic.
Lubomirscy wobec rokoszu sandomierskiego
Authors: Goszczyński Artur
Published: October 2022

The reign of Zygmunt III Waza was crucial to the growth of the Lubomirski family. At the moment of assuming the throne by the mentioned king, Sebastian Lubomirski owned a considerable property resulting from leasehold of Cracow salt mines granted by Stefan Batory. However he did not hold any political office that would give him a real influence on the shape of the state. The successive offices of Castellan of Małogoszcz, Castellan of Biecz and Castellan of Wojnicz were supposed to encourage Lubomirski to join to the royal camp. One of the most important issues discussed in the present paper is the conflict between the Count of Wiśnicz and Andrzej Bobola concerning the exploitation of salt deposits near Lednica. The disagreement took place shortly before the rebellion and worsened the relations between the court and the Lubomirski family. The aim of this article is to show the Lubomirskis’ attitude towards the rebellion as well as its consequences for the might of the family.
Konfederacje w opiniach sejmików poselskich w czasach Rady Nieustającej
Authors: Filipczak Witold
Published: October 2022

The main aim of the present article is to investigate a specificity of Polish confederations with regard to sejmiks’ resolutions as an adjunct to current research. The mentioned investigation is based on the instructions handed over to Sejm deputies from 1776 to 1788, sejmiks’ records, correspondence and political writings connected with sejmiks. Research on opinions expressed in the instructions holds importance as they reflect views represented by the elites of the sejmiks as well as groups from which their true authors originated. It is vital to bear in mind that the instructions had to obtain acceptance of the nobles taking part in a particular assembly in advance. The timeframes of the article are related to the fact that the attitudes towards the confederations became prominent in documents connected with sejmiks in 1776 (the reaction to the activity of the confederation controlling the Partition Sejm) and in the days of pre-partition deliberations that established the resolutions applying to the abuses of two last general federations and its impact on the results of confederate Sejms.
Student research
Authors: Leow Abigail
Published: October 2022

This is the third article in a series on musical development. Here Abigail Leow shares with us insight into the ‘behind the scenes’ of conducting research as she introduces her study around musical development.
De la llengua, encara
Authors: Terrassa i Cosí Cesc
Published: October 2022

Editorial
creació d’un espectacle a secundària a través del debat teatral "Kitchen Table"
Authors: Vela Carmona Xesca
Published: October 2022

En aquest article s’explica l’aplicació de la Kitchen Table, discussió teatral, amb 12 adolescents de l’Institut de Secundària Vallbona d’Anoia que participen en l’optativa d’Arts Escèniques i Dansa a 4t d’Educació Secundària Obligatòria. La docent-investigadora va utilitzar aquesta tècnica per crear espectacles amb l’alumnat, a partir dels seus testimonis. La Kitchen Table va oferir als joves l’oportunitat d’anar un grau més en la verbalització dels seus pensaments, per aplicar-los a la creació d’un espectacle final. La Kitchen Table es confirma com un procés metacognitiu en què l’adolescent cerca la seva identitat dins el grup.
Literatura infantil y lectura dialógica. La formación de educadores desde la investigación
Authors: García-Parejo Isabel
Published: October 2022

Reseña
Literatura infantil y lectura dialógica. La formación de educadores desde la investigación, por Amando López, Valero, Eduardo Encabo Fernández, Isabel Jerez Martínez y Lourdes Hernández Delgado (2021).  Octaedro. 140 págs. ISBN: 978-84-18819-40-7
Aprendizaje-Servicio en Ciencias de la Actividad Física y el Deporte: buenas prácticas de Educación Física en colectivos vulnerables
Authors: Solà Santesmases Josep
Published: October 2022

La metodología Aprendizaje-Servicio ofrece una vivencia práctica plenamente competencial y genuina para una universidad que no puede existir ajena a la realidad social. El artículo revisa la relación entre el Aprendizaje-Servicio y los estudios de Ciencias de la Actividad Física y el Deporte, planteando una propuesta de intervención acorde con las fases ampliamente justificadas por la bibliografía reciente. Además, se ejemplifican intervenciones singulares de Educación Física en menores con riesgo de exclusión social y en adolescentes con discapacidad psíquica. En base a la relación biunívoca entre estudiantes e instituciones, dichas sesiones deberán adaptarse a las necesidades específicas de cada grupo social. Estas intervenciones se valoran como buenas prácticas de compromiso social universitario, ya que deben estar plenamente adaptadas a las condiciones de heterogeneidad de grupos poblacionales escasamente reconocibles en el currículum, desde la comprensión empática por parte de los estudiantes. No obstante, se plantean reflexiones de mejora basadas en la elegibilidad de las propuestas o en posibles planteamientos transversales entre diferentes estudios.