scholarly journals Thermo-Viscoelastic Response of Protein-Based Hydrogels

2021 ◽  
Vol 8 (6) ◽  
pp. 73
Author(s):  
Aleksey D. Drozdov ◽  
Jesper deClaville Christiansen
Keyword(s):  
Wide Spectrum ◽  
Polymer Network ◽  
Coiled Coil ◽  
Viscoelastic Behavior ◽  
Viscoelastic Response ◽  
Potential Applications ◽  
Linear Viscoelastic Behavior ◽  
Protein Gels ◽  
Shear Relaxation ◽  
The One

Because of the bioactivity and biocompatibility of protein-based gels and the reversible nature of bonds between associating coiled coils, these materials demonstrate a wide spectrum of potential applications in targeted drug delivery, tissue engineering, and regenerative medicine. The kinetics of rearrangement (association and dissociation) of the physical bonds between chains has been traditionally studied in shear relaxation tests and small-amplitude oscillatory tests. A characteristic feature of recombinant protein gels is that chains in the polymer network are connected by temporary bonds between the coiled coil complexes and permanent cross-links between functional groups of amino acids. A simple model is developed for the linear viscoelastic behavior of protein-based gels. Its advantage is that, on the one hand, the model only involves five material parameters with transparent physical meaning and, on the other, it correctly reproduces experimental data in shear relaxation and oscillatory tests. The model is applied to study the effects of temperature, the concentration of proteins, and their structure on the viscoelastic response of hydrogels.

Investigating the Non-Linear Viscoelastic Behavior of Filled Rubber Compounds Through Fourier Transform Rheometry

2005 ◽  
Vol 78 (1) ◽  
pp. 54-75 ◽  
Author(s):  
Jean L. Leblanc
Keyword(s):  
Fourier Transform ◽  
Volume Fraction ◽  
Viscoelastic Behavior ◽  
Viscoelastic Response ◽  
Constant Frequency ◽  
Filled Rubber ◽  
Rubber Compounds ◽  
Non Linear ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic

Abstract Fourier transform (FT) rheometry was used to investigate the non-linear viscoelastic behavior of a series of carbon black filled rubber compounds with various filler levels. Using a purposely modified commercial dynamic rheometer, i.e. the Rubber Process Analyzer RPA 2000® (Alpha Technologies), special strain sweep tests protocols were designed and performed in order to capture the actual strain and torque signals up to 500% deformation at constant frequency and temperature. FT yielded the main component and harmonics of strain and torque signals. Results show that the quality of the applied strain signal somewhat deteriorates with increasing stiffness of filled compounds, but remains excellent in the high strain region, where the non-linear viscoelastic response of the materials is investigated. Above a filler volume fraction of around 12–13%, tested materials no longer exhibit a linear viscoelastic response, at least in the strain window investigated, and the FT rheometry results are more complex than what was observed with pure gum samples. This means that most practical rubber compounds are intrinsically non-linear. By essence, FT rheometry is a valid technique for both the linear and the non-linear domains and, as shown, provides original information about complex polymer systems such as filled rubber compounds.

Noticing and analysis of pedagogical practices in mathematics

2019 ◽  
Author(s):  
Yuri Morales López ◽  
Marianela Alpízar Vargas ◽  
Ana Lucía Alfaro Arce ◽  
Vicenç Font-Moll
Keyword(s):  
Classroom Management ◽  
Wide Spectrum ◽  
Math Education ◽  
Pedagogical Practices ◽  
Math Teachers ◽  
Education Activity ◽  
The One ◽  
Analysis Models ◽  
Teacher's Knowledge ◽  
Math Teacher

The purpose of this presentation is to show elements associated to the study and analysis of pedagogical practices used by mathematics teachers, taking into consideration different approaches and conceptions derived from theories related to the role of the math teacher. The project highlights the need to use different strategies to analyze the processes occurring in the activities and tasks organized and implemented by the teacher. One of the main tasks in teacher training is to promote the capacity to noticing on the pedagogical activity, where noticing is understood as an inherent process to improve the quality of classroom management. In addition, different analysis models should be compared using examples and experiential practices and the different theories and research projects developed in this field related to this type of analysis. Knowing what happens in the classroom is a task inherent to the math teacher. For sure, if the teacher does not understand or is even able to perceive what is happening in the class, improvement actions are very difficult to implement. Consequently, math teachers must develop the capability of analyzing their pedagogical activity and the related elements. It is not about isolating variables and looking for causal relationships, but rather about understanding the teacher’s activity as the center of the multiple situations occurring in the classroom, which may be known more in depth, if the attention is focused on the organization, ordering, and execution of the tasks planned by the teacher. It must also be understood that the competence of analyzing mentioned here is not an isolated activity without an effect. Such analysis must be approached from an active perspective where scenarios are generated to mitigate complex situations or to value an approach different than the one happening in the classroom. Being aware that there are many aspects to analyze (most likely almost everything that happens is analyzable), we must take a stand on which situations are highly related to what happens in our classroom and which could eventually happen. With such a wide spectrum, some questions that need to be addressed are: What is important in the math education activity and who defines what is important? What elements are of interest to math teachers? How does the analysis conducted relate to the different models of the teacher's knowledge? How does our previous experience influence the assessments we make? How do we distinguish elements of interest to analysis? What is the relationship between reflecting and analyzing? At what stages of the teacher’s activity is an analysis required? What is the ultimate purpose of analyzing teaching activities? What competencies or skills are related to the analysis? What types of analysis are appropriate (content, cognitive, media, among others)? How can we balance the actions derived from the analyses we conduct? From all these questions the most important one that can guide the study of this reflection would be: What should be assessed in pedagogical activities and what is the objective of analyzing such pedagogical activities in math education?

OnPoint: A package for online experiments in motor control and motor learning

2020 ◽  
Author(s):  
Jonathan Sanching Tsay ◽  
Alan S. Lee ◽  
Guy Avraham ◽  
Darius E. Parvin ◽  
Jeremy Ho ◽  
...  
Keyword(s):  
Motor Control ◽  
Motor Learning ◽  
Open Source Software ◽  
Research Progress ◽  
Global Pandemic ◽  
Large N ◽  
Open Source Software Package ◽  
Potential Applications ◽  
Temporal And Spatial ◽  
The One

Motor learning experiments are typically run in-person, exploiting finely calibrated setups (digitizing tablets, robotic manipulandum, full VR displays) that provide high temporal and spatial resolution. However, these experiments come at a cost, not limited to the one-time expense of purchasing equipment but also the substantial time devoted to recruiting participants and administering the experiment. Moreover, exceptional circumstances that limit in-person testing, such as a global pandemic, may halt research progress. These limitations of in-person motor learning research have motivated the design of OnPoint, an open-source software package for motor control and motor learning researchers. As with all online studies, OnPoint offers an opportunity to conduct large-N motor learning studies, with potential applications to do faster pilot testing, replicate previous findings, and conduct longitudinal studies (GitHub repository: https://github.com/alan-s-lee/OnPoint).

scholarly journals A Highly Versatile Polymer Network Based on Liquid Crystalline Dendrimers

2021 ◽  
Vol 22 (11) ◽  
pp. 5740
Author(s):  
Ramón Cervera-Procas ◽  
José-Luis Serrano ◽  
Ana Omenat
Keyword(s):  
Smart Materials ◽  
Liquid Crystalline ◽  
Organic Dyes ◽  
Polymer Network ◽  
Viscoelastic Behavior ◽  
Diverse Range ◽  
Polymeric Systems ◽  
System A ◽  
Porous Microstructure ◽  
Solvent Molecules

Highly functional macromolecules with a well-defined architecture are the key to designing efficient and smart materials, and these polymeric systems can be tailored for specific applications in a diverse range of fields. Herein, the formation of a new liquid crystalline polymeric network based on the crosslinking of dendrimeric entities by the CuI-catalyzed variant of the Huisgen 1,3-dipolar cycloaddition of azides and alkynes to afford 1,2,3-triazoles is reported. The polymeric material obtained in this way is easy to process and exhibits a variety of properties, which include mesomorphism, viscoelastic behavior, and thermal contraction. The porous microstructure of the polymer network determines its capability to absorb solvent molecules and to encapsulate small molecules, like organic dyes, which can be released easily afterwards. Moreover, all these properties may be easily tuned by modifying the chemical structure of the constituent dendrimers, which makes this system a very interesting one for a number of applications.

scholarly journals Topological guided-mode resonances at non-Hermitian nanophotonic interfaces

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ki Young Lee ◽  
Kwang Wook Yoo ◽  
Youngsun Choi ◽  
Gunpyo Kim ◽  
Sangmo Cheon ◽  
...  
Keyword(s):  
Fundamental Study ◽  
One Dimensional ◽  
Guided Mode ◽  
Wall Structures ◽  
Potential Applications ◽  
Photonic Microstructures ◽  
Guided Mode Resonance ◽  
The One ◽  
Photonic Band ◽  
Topological Correlations

Abstract The topological properties of photonic microstructures are of great interest because of their experimental feasibility for fundamental study and potential applications. Here, we show that robust guided-mode-resonance states exist in photonic domain-wall structures whenever the complex photonic band structures involve certain topological correlations in general. Using the non-Hermitian photonic analogy of the one-dimensional Dirac equation, we derive essential conditions for photonic Jackiw-Rebbi-state resonances taking advantage of unique spatial confinement and spot-like spectral features which are remarkably robust against random parametric errors. Therefore, the proposed resonance configuration potentially provides a powerful method to create compact and stable photonic resonators for various applications in practice.

scholarly journals A Textile Waste Fiber-Reinforced Cement Composite: Comparison between Short Random Fiber and Textile Reinforcement

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3742
Author(s):  
Payam Sadrolodabaee ◽  
Josep Claramunt ◽  
Mònica Ardanuy ◽  
Albert de la Fuente
Keyword(s):  
Construction Material ◽  
Drying Shrinkage ◽  
Cement Composite ◽  
Nonwoven Fabric ◽  
Textile Waste ◽  
Nonwoven Fabrics ◽  
Potential Applications ◽  
Reinforced Cement ◽  
The One ◽  
Garment And Textile

Currently, millions of tons of textile waste from the garment and textile industries are generated worldwide each year. As a promising option in terms of sustainability, textile waste fibers could be used as internal reinforcement of cement-based composites by enhancing ductility and decreasing crack propagation. To this end, two extensive experimental programs were carried out, involving the use of either fractions of short random fibers at 6–10% by weight or nonwoven fabrics in 3–7 laminate layers in the textile waste-reinforcement of cement, and the mechanical and durability properties of the resulting composites were characterized. Flexural resistance in pre- and post-crack, toughness, and stiffness of the resulting composites were assessed in addition to unrestrained drying shrinkage testing. The results obtained from those programs were analyzed and compared to identify the optimal composite and potential applications. Based on the results of experimental analysis, the feasibility of using this textile waste composite as a potential construction material in nonstructural concrete structures such as facade cladding, raised floors, and pavements was confirmed. The optimal composite was proven to be the one reinforced with six layers of nonwoven fabric, with a flexural strength of 15.5 MPa and a toughness of 9.7 kJ/m2.

scholarly journals X/XY Chromosome Mosaicism: Turner Syndrome and Other Clinical Conditions

2009 ◽  
Vol 63 (1-2) ◽  
pp. 1-4
Author(s):  
Irena Andriuškevičiūtė ◽  
Loreta Šalomskienė ◽  
Lina Jurkėnienė ◽  
Algimantas Sinkus
Keyword(s):  
Turner Syndrome ◽  
Y Chromosome ◽  
Wide Spectrum ◽  
Normal Male ◽  
Chromosome Mosaicism ◽  
Lymphocyte Cultures ◽  
Nosological Entity ◽  
The One ◽  
Clinical Conditions ◽  
Pierre Robin

X/XY Chromosome Mosaicism: Turner Syndrome and Other Clinical Conditions The 45,X/46,XY mosaicism shows a wide spectrum of phenotypes ranging from females with Turner syndrome, male or female pseudohermaphroditism, to appearently normal male development. Chromosome anomalies accompanying Turner syndrome were found in lymphocyte cultures of 236 patients. Chromosomal analysis revealed the karyotype 45,X in 118 (50.0%) patients. X monosomy mosaics or structural rearrangements of the X chromosome was established in 112 (47.5%) patients. The Y chromosome was found in six (2.5%) patients with typical features of Turner syndrome. In five mosaics 45,X/46,XY the proportion of the XY clone ranged from 46% to 76%. In one Turner syndrome patient only 47,XYY cells were found (solely blood culture investigated). In most cases of 45,X/46,XY mosaicism, the cause is considered to be the loss of the Y chromosome because of nondisjunction after normal disomic fertilisation. Five other patients with X/XY chromosome mosaicism showed mixed gonadal dysgenesis (two patients), one male pseudohermafroditism, one male with Pierre Robin syndrome, and one normal male phenotype. In two non Turner syndrome patients nondisjunction of the primary clone 46,XY was obvious and resulted in mosaicism 45,X/46,XY/47,XYY, the one patient contained dicentric Y. The similarities between X/XY Turner syndrome and other nosological entity of females possessing Y chromosome — the Swyer syndrome — are discussed.

Drug Release Mechanism of Fast Temperature-Responsive Soy Protein/PNIPAAm IPN Hydrogels

2013 ◽  
Vol 781-784 ◽  
pp. 803-807 ◽  
Author(s):  
Yong Liu ◽  
Shou Lian Wei ◽  
Miao Chan Liao
Keyword(s):  
Soy Protein ◽  
Polymer Network ◽  
Reaction Medium ◽  
Interpenetrating Polymer Network ◽  
Release Mechanism ◽  
Porous Structures ◽  
Temperature Responsive ◽  
Drug Release Mechanism ◽  
Potential Applications ◽  
Fast Release

Fast temperature-responsive interpenetrating polymer network hydrogels based on soy protein and poly(N-isopropylacrylamide) (PNIPAAm) were prepared using the sodium bicarbonate (NaHCO3) solutions as the reaction medium. The structure and properties were characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The bovine serum albumin (BSA) release behaviors and release mechanism were also investigated. The results show that the proposed hydrogels have high porous structures and have a fast release rate. The BSA release mechanism belongs to an anomalous transport and the Fickian contribution is dominant. The proposed hydrogels may have the potential applications in the field of biomedical materials such as in the controlled release of drugs.

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