Polylactide (PLA) is one of the most commonly used biomaterials nowadays, with many recognized benefits, particularly in the packaging and single-use products industries. However, little research has been conducted on its stretching behavior. This work investigates the optimal conditions of biaxial stretching of injection-molded PLA samples produced under different processing conditions (pressure, drying, and pre-processing by extrusion, to simulate a recycling step). The injection-molded samples were characterized to determine their mechanical, thermal and thermo-mechanical behavior, water absorption, thermal behavior, and crystallization kinetics. The extruded samples showed reduced thermal stability, lower viscosity, decreased mechanical properties, and higher crystallization rates due to thermal degradation. However, the stretched samples provided similar properties regardless of the materials pre-processing. Regarding the assessment of the biaxial stretching process, processing at lower temperatures provides the films with a higher yield and breaking strength, while the time and strain rates have little influence on such properties. It was then determined that 82 °C is the optimal temperature for stretching the PLA samples. An increase in the stretch ratio provided a higher elastic modulus and higher values of opacity due to an increased crystallinity induced by stress during the process. Films as thin as 50 μm can be obtained by biaxially stretching injection-molded preforms, producing a deformation over 150% and acquiring good mechanical properties: about 90 MPa for the yield and a breaking strength and elastic modulus of 4000 MPa.
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http://dx.doi.org/10.3390/ma16145114 | DOI Listing |
Infect Chemother
December 2024
Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea.
The Korean Society of Infectious Diseases has been regularly publishing guidelines for adult immunization since 2007. Following the release of coronavirus disease 2019 (COVID-19) vaccination recommendations in 2023, significant changes have occurred due to the emergence of new variant strains and the waning immunity from previous vaccinations. This article provides a comprehensive update as of November 2024, incorporating the latest evidence and guidelines.
View Article and Find Full Text PDFJ Neuroeng Rehabil
January 2025
Hulse Spinal Cord Injury Research Lab, Shepherd Center, 2020 Peachtree Road NW, Atlanta, GA, USA.
Background: There is growing interest in use of transcutaneous spinal stimulation (TSS) for people with neurologic conditions both to augment volitional control (by facilitating motoneuron excitability), and to decrease spasticity (by activating inhibitory networks). Various electrode montages are used during TSS, with little understanding of how electrode position influences spinal circuit activation. We sought to identify the thoracolumbar electrode montage associated with the most robust activation of spinal circuits by comparing posterior root-muscle reflexes (PRM reflexes) elicited by 6 montages.
View Article and Find Full Text PDFBMC Microbiol
January 2025
Department of Medical Microbiology and Immunology, Faculty of Medicine, Benha University, Benha, Egypt.
Background: Novel platforms using nanotechnology-based medicines have exponentially increased in our daily lives. The unique characteristics of metal oxide and noble metals nanoparticles make them suitable for different fields including antimicrobial agents, cosmetics, textiles, wound dressings, and anticancer drug carriers.
Methods: This study focuses on the biosynthesis of small-sized SNPs using exo-metabolites of Fusarium oxysporum via bioprocess optimization using Plackett-Burman (PBD) and central composite designs (CCD) while evaluating their multifaceted bioactivities.
Sci Rep
January 2025
Young Researchers and Elite Club, Omidiyeh Branch, Islamic Azad University, Omidiyeh, Iran.
Accurate estimation of interfacial tension (IFT) between nitrogen and crude oil during nitrogen-based gas injection into oil reservoirs is imperative. The previous research works dealing with prediction of IFT of oil and nitrogen systems consider synthetic oil samples such n-alkanes. In this work, we aim to utilize eight machine learning methods of Decision Tree (DT), AdaBoost (AB), Random Forest (RF), K-nearest Neighbors (KNN), Ensemble Learning (EL), Support Vector Machine (SVM), Convolutional Neural Network (CNN) and Multilayer Perceptron Artificial Neural Network (MLP-ANN) to construct data-driven intelligent models to predict crude oil - nitrogen IFT based upon experimental data of real crude oils samples encountered in underground oil reservoirs.
View Article and Find Full Text PDFSci Rep
January 2025
Innovation Institute for Sustainable Maritime Architecture Research and Technology, Qingdao University of Technology, Qingdao, 266033, People's Republic of China.
During the hot summer months, the significant temperature disparity between outdoor and indoor air-conditioned spaces can lead to thermal discomfort and pose a potential health risk. Transition areas such as corridors and elevator lobbies, serving as intermediary zones connecting indoors and outdoors, have been found effective in mitigating this thermal discomfort. In this study, three different temperatures (25 °C-case 1, 27 °C-case 2, and 29 °C-case 3) were employed to investigate the dynamic physiological regulation and thermal perception response of individuals when transitioning from an outdoor environment into an indoor neutral room through a transition space.
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