bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functionalization of biopolymer fibers with magnetic nanoparticles
Authors: Strassburg Stephen , Mayer Kai , Scheibel Thomas 
Published: January 2021

Abstract
Hybrid fibers consisting of biopolymers and inorganic nanoparticles are receiving increasing attention due to their unique properties. Commonly, the nanoparticles are chosen for their intrinsic properties such as magnetic, thermal, or electrical conductivity. The biopolymer component of the hybrid fiber is chosen for its mechanical properties and ability to act as a scaffold or matrix for the nanoparticles. While there are many fiber-forming synthetic polymers, there has been a recent interest in replacing these systems with biopolymers due to their sustainability, biocompatibility, nontoxicity, and biodegradability. Fibers made from biopolymers have one additional benefit over synthetic polymers as they make good scaffolds for embedding nanoparticles without the need of any additional bonding agents. In particular, naturally occurring biopolymers such as proteins exhibit a myriad of interactions with nanoparticles, including ionic, H-bonding, covalent, Van der Waals, and electrostatic interactions. The diverse range of interactions between magnetic nanoparticles and biopolymers makes resulting hybrid fibers of particular interest as magnetic-responsive materials. Magnetically responsive hybrid biopolymer fibers have many features, including enhanced thermal stabilities, strong mechanical toughness, and perhaps most interestingly multifunctionality, allowing for a wide range of applications. These applications range from biosensing, filtration, UV shielding, antimicrobial, and medical applications, to name a few. Here, we review established hybrid fibers consisting of biopolymers and nanoparticles with a primary focus on biopolymers doped with magnetic nanoparticles and their various putative applications.
Studies about the design of magnetic bionanocomposite
Authors: Müller Robert , Kuchinka Janna , Heinze Thomas 
Published: January 2021

AbstractMagnetic nanocomposites are a class of smart materials that have attracted recent interest as drug delivery systems or as medical implants. A new approach toward the biocompatible nanocomposites suitable for remote melting is presented. It is shown that magnetite nanoparticles (MNPs) can be embedded into a matrix of biocompatible thermoplastic dextran esters. For that purpose, fatty acid esters of dextran with adjustable melting points in the range of 30–140 °C were synthesized. Esterification of the polysaccharide by activation of the acid as iminium chlorides guaranteed mild reaction conditions leading to high-quality products as confirmed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy as well as by gel permeation chromatography (GPC). A method for the preparation of magnetically responsive bionanocomposites (BNCs) was developed consisting of combined dissolution/suspension of the dextran ester and hydrophobized MNPs in an organic solvent followed by homogenization with ultrasonication, casting of the solution, drying and melting of the composite for a defined shaping. This process leads to a uniform distribution of MNPs in BNC as revealed by scanning electron microscope (SEM). Samples of different geometries were exposed to high-frequency alternating magnetic field (AMF). It could be shown that defined remote melting of such biocompatible nanocomposites is possible for the first time. This may lead to a new class of magnetic remote-control systems, which are suitable for controlled release applications or self-healing materials. BNCs containing biocompatible dextran fatty acid ester melting close to human body temperature were prepared and loaded with Rhodamine B (RhB) or green fluorescent protein (GFP) as model drugs to evaluate their potential use as drug delivery system. The release of the model drugs from the magnetic BNC investigated under the influence of a high-frequency AMF (20 kA/m at 400 kHz) showed that on-demand release is realized by applying the external AMF. The BNC possessed a long-term stability (28 d) of the incorporated iron oxide particles after incubation in artificial body fluids. Temperature-dependent mobility investigations of MNP in the molten BNC were carried out by optical microscopy, magnetometry, alternating current (AC) susceptibility, and Mössbauer spectroscopy measurements. Optical microscopy shows a movement of agglomerates and texturing in the micrometer scale, whereas AC susceptometry and Mössbauer spectroscopy investigations reveal that the particles perform diffusive Brownian motion in the liquid polymer melt as separated particles rather than as large agglomerates. Furthermore, a texturing of MNP in the polymer matrix by a static magnetic field gradient was investigated. First results on the preparation of cross-linkable dextran esters are shown. Cross-linking after irradiation of the BNC prevents melting that can be used to influence texturing procedures.
Magneto-mechanical properties of elastic hybrid composites
Authors: Borin Dmitry , Stepanov Gennady 
Published: January 2021

Abstract
The paper gives an overview of tunable elastic magnetic composites based on silicon rubber matrix highly filled with a magnetic soft and hard filler. The magnetic soft phase, which is represented by iron microparticles, allows active control of the physical properties of the composites, while the magnetically hard phase (e.g. neodymium–iron–boron alloy microparticles) is mainly responsible for passive adjustment of the composite. The control is performed by the application of an external magnetic field in situ, and passive adjustment is performed by means of pre-magnetization in order to change material remanent magnetization, i.e. the initial state. The potential and limits of active control and passive tuning of these composites in terms of their magneto-mechanical behavior are presented and discussed.
Hybrid magnetic elastomers prepared on the basis of a SIEL-grade resin and their magnetic and rheological properties
Authors: Stepanov Gennady V. , Borin Dmitry Yu. , Bakhtiiarov Anton V. , Storozhenko Pavel A. 
Published: January 2021

Abstract
Hybrid magnetic elastomers (HMEs) belong to a novel type of magnetocontrollable elastic materials capable of demonstrating extensive variations of their parameters under the influence of magnetic fields. Like all cognate materials, HMEs are based on deformable polymer filled with a mixed or modified powder. The complex of properties possessed by the composite is a reflection of interactions occurring between the polymer matrix and the particles also participating in interactions among themselves. For example, introduction of magnetically hard components into the formula results in the origination of a number of significantly different behavioral features entirely unknown to magnetorheological composites of the classic type. Optical observation of samples based on magnetically hard filler gave the opportunity to establish that initial magnetization imparts magnetic moments to initially unmagnetized grains, as a result of which chain-like structures continue to be a feature of the material even after external field removal. In addition, applying a reverse field causes them to turn into the polymer as they rearrange into new ring-like structures. Exploration of the relationship between the rheological properties and magnetic field conducted on a rheometer using vibrational mechanical analysis showed an increase of the relative elastic modulus by more than two orders of magnitude or by 3.8 MPa, whereas the loss factor exhibited steady growth with the field up to a value of 0.7 being significantly higher than that demonstrated by elastomers with no magnetically hard particles. At the same time, measuring the electroconductivity of elastomers filled with a nickel-electroplated carbonyl iron powder made it possible to observe that such composites demonstrated an increase of variation of the resistivity of the composite influenced by magnetic field in comparison to elastomers containing untreated iron particles. The studies conducted indicate that this material exhibits both magnetorheological and magnetoresistive effect and does indeed have the potential for use in various types of devices.
Magnetostriction in elastomers with mixtures of magnetically hard and soft microparticles: effects of nonlinear magnetization and matrix rigidity
Authors: Stolbov Oleg V. , Sánchez Pedro A. , Kantorovich Sofia S. , Raikher Yuriy L. 
Published: January 2021

Abstract
In this contribution, a magnetoactive elastomer (MAE) of mixed content, i.e., a polymer matrix filled with a mixture of magnetically soft and magnetically hard spherical particles, is considered. The object we focus on is an elementary unit of this composite, for which we take a set consisting of a permanent spherical micromagnet surrounded by an elastomer layer filled with magnetically soft microparticles. We present a comparative treatment of this unit from two essentially different viewpoints. The first one is a coarse-grained molecular dynamics simulation model, which presents the composite as a bead-spring assembly and is able to deliver information of all the microstructural changes of the assembly. The second approach is entirely based on the continuum magnetomechanical description of the system, whose direct yield is the macroscopic field-induced response of the MAE to external field, as this model ignores all the microstructural details of the magnetization process. We find that, differing in certain details, both frameworks are coherent in predicting that a unit comprising magnetically soft and hard particles may display a nontrivial reentrant (prolate/oblate/prolate) axial deformation under variation of the applied field strength. The flexibility of the proposed combination of the two complementary frameworks enables us to look deeper into the manifestation of the magnetic response: with respect to the magnetically soft particles, we compare the linear regime of magnetization to that with saturation, which we describe by the Fröhlich–Kennelly approximation; with respect to the polymer matrix, we analyze the dependence of the reentrant deformation on its rigidity.
Electric degradation in PZT piezoelectric ceramics under a DC bias
Authors: Zhang Jing , Pan Pinghua , Jiang Ping , Qin Jie , Hu Jiansong 
Published: January 2021

Abstract
In order to accurately evaluate the service life and failure mechanism of the PZT piezoelectric ceramics, the electric degradation process of the PZT ceramics with and sans doping under a DC voltage of 380V, in a surrounding environment of 90∘C and 85% RH has been investigated using a self-made device. The experimental results show that the degradation rate of the pure PZT ceramic is lower than that of ceramics with doping in the same condition. Furthermore, the electrical properties of the ceramics tend to decrease during the electric degradation. The doping increases the defects of ceramics, resulting in that the silver ion transfer from the anode to the cathode under the continuous DC bias, which can further form a metal band, increasing the conductivity, but deteriorating the service life.
A New Portable Device to Reliably Measure Maximal Strength and Rate of Force Development of Hip Adduction and Abduction
Authors: Gonçalves Basílio A.M. , Mesquita Ricardo N.O. , Tavares Francisco , Brito João , Correia Paulo , Santos Paulo , Mil-Homens Pedro 
Published: January 2021

Abstract
Gonçalves, BM, Mesquita, RNO, Tavares, F, Brito, J, Correia, P, Santos, P, and Mil-Homens, P. A new portable device to reliably measure maximal strength and rate of force development of hip adduction and abduction. J Strength Cond Res 36(9): 2465–2471, 2022—Groin injuries are a major issue in sports involving kicking or quick changes of direction. Decreased hip adduction and abduction strength have been indicated as one of the main risk factors for groin injury. The methods currently available to measure hip adduction and abduction strength are reliable but highly dependent on the evaluator skills. Furthermore, several studies have reported the reliability of maximal strength (MVIC), but very few studies investigated the reliability of explosive strength (RFD), a parameter that has been previously shown to have a higher functional value. The aim of the current investigation was to assess the reliability of a user-independent portable dynamometer that concurrently measures MVIC and RFD. Twenty-five healthy young subjects performed maximal isometric hip adduction and abduction in both sitting and supine positions. Measurements occurred in 2 different days separated by 48–72 hours. Test-retest reliability was calculated for both MVIC and RFD. Both MVIC and RFD showed good relative reliability (intraclass correlation coefficient = 0.77–0.98) with no differences between positions or muscle actions. Measurement error was similar between positions for MVIC in both hip adduction and abduction. Measurements of RFD showed higher reliability using a time window of at least 0–100 milliseconds, and lower measurement error was observed in sitting for adduction and in supine for abduction. This study shows that portable dynamometry can be used to concurrently measure hip adduction and abduction maximal and explosive strength, with levels of reliability that are similar to previously described methods.
Effects of a Strength-Dominated Exercise Program on Physical Fitness and Cognitive Performance in Preschool Children
Authors: Wick Kristin , Kriemler Susi , Granacher Urs 
Published: January 2021

Abstract
Wick, K, Kriemler, S, and Granacher, U. Effects of a strength-dominated exercise program on physical fitness and cognitive performance in preschool children. J Strength Cond Res 35(4): 983–990, 2021—Childhood is characterized by high neuroplasticity that affords qualitative rather than quantitative components of physical activity to maximize the potential to sufficiently develop motor skills and foster long-term engagement in regular physical activity. This study examined the effects of an integrative strength-dominated exercise program on measures of physical fitness and cognitive performance in preschool children. Children aged 4–6 years from 3 kindergartens were randomized into an intervention (INT) group (n = 32) or a control group (n = 22). The 10-week intervention period was conducted 3 times per week (each session lasted 30 minutes) and included exercises for the promotion of muscle strength and power, coordination, and balance. Pre and post training, tests were conducted for the assessment of muscle strength (i.e., handgrip strength), muscle power (i.e., standing long jump), balance (i.e., timed single-leg stand), coordination (hopping on right/left leg), and attentional span (i.e., “Konzentrations-Handlungsverfahren für Vorschulkinder” [concentration-action procedure for preschoolers]). Results from 2 × 2 repeated-measures analysis of covariance revealed a significant (p ≤ 0.05) and near significant (p = 0.051) group × time interaction for the standing long jump test and the Konzentrations-Handlungsverfahren. Post hoc tests showed significant pre-post changes for the INT (p < 0.001; d = 1.53) but not the CON (p = 0.72; d = 0.83). Our results indicate that a 10-week strength-dominated exercise program increased jump performance with a concomitant trend toward improvements in attentional capacity of preschool children. Thus, we recommend implementing this type of exercise program for preschoolers.
Can Team-Sport Athletes Accurately Run at Submaximal Sprinting Speeds? Implications for Rehabilitation and Warm-Up Protocols
Authors: Darrall-Jones Joshua , Roe Gregory , Cremen Eoin , Jones Ben 
Published: January 2021

Abstract
Darrall-Jones, J, Roe, G, Cremen, E, and Jones, B. Can team-sport athletes accurately run at submaximal sprinting speeds? Implications for rehabilitation and warm-up protocols. J Strength Cond Res 36(8): 2218–2222, 2022—The aim of this study is to examine the ability of team-sport athletes to accurately run at a range of submaximal sprint velocities (60–90% maximal velocity; Vmax) under verbal instruction without any objective feedback. Twelve professional male rugby union players (age 19.7 ± 0.9 years, body mass 98.3 ± 13.9 kg, height 184.0 ± 7.5 cm) were verbally instructed to complete three 40-m sprints at each of 60, 70, 80, and 90% of Vmax in a randomized order. Percentage Vmax achieved during each sprint was compared with criterion velocities calculated from Vmax testing undertaken a week prior. Players underestimated (ran faster) their sprint velocity when asked to run at 60% (very large to extremely large mean bias, 23%; range, 57–88% Vmax), 70% (large to very large, 11%; 67–93% Vmax), and 80% (small, 2%; 71–91% Vmax) of their Vmax, whereas overestimated (ran slower) their sprint velocity when asked to run at 90% Vmax (moderate, −4%; 77–95% Vmax). Team sport players may require objective feedback when performing submaximal sprinting to ensure that velocities achieved are similar to those prescribed. This may be particularly important where graded exposure to maximum velocities is required, for example during rehabilitation or warm-ups.
Potential Predictors of Vertical Jump Performance: Lower Extremity Dimensions and Alignment, Relative Body Fat, and Kinetic Variables
Authors: Daugherty Hailey J. , Weiss Lawrence W. , Paquette Max R. , Powell Douglas W. , Allison Lindsey E. 
Published: January 2021

Abstract
Daugherty, HJ, Weiss, LW, Paquette, MR, Powell, DW, and Allison, LE. Potential predictors of vertical jump performance: Lower extremity dimensions and alignment, relative body fat, and kinetic variables. J Strength Cond Res 35(3): 616–625, 2021—The association of structural and kinetic variables with restricted vertical jump (RVJ) displacement without and with added mass was examined in 60 men and women. Added mass (weighted vest) simulated a 5% increase in body fat (BF%). Independent variables included BF%, thigh length, and static Q-angle (Q-angles), and while performing RVJ, different expressions of frontal-plane knee angle (FPKA), dynamic Q-angle (Q-angled), vertical ground reaction force (vGRF), concentric vertical impulse (Iz), concentric rate of force development (CRFD), and vertical power (Pz). Variables having significant (p ≤ 0.05) negative correlations with RVJ displacement included BF% (r = −0.76) and Q-angles (r = −0.55). Those having significant (p ≤ 0.05) positive correlations with RVJ displacement included peak and average concentric Pz (r range = 0.74–0.81), peak and average concentric vGRF (r range = 0.46–0.67), Iz (r range = 0.32–0.54), thigh length (r = 0.31), minimum Q-angled (r = 0.31), and maximum FPKA (r = 0.28). Variables not associated (p > 0.05) with RVJ displacement included minimum and excursion FPKA (r = 0.11 and 0.23), maximum, excursion, and average Q-angled (r = 0.24, 0.11, and 0.22), and CRFD (r range = 0.19–0.24). A simple regression model predicted RVJ displacement (p = 1.00) for the simulated 5% increase in body fat. To maximize jumping performance, (a) high levels of body fat should be avoided, (b) peak and average Pz, vGRF, and Iz should be maximized through training, and (c) having a lower Q-angles is associated with better jumping ability.
¿Qué puedo esperar del futuro?
Authors: Aranda Fraga Fernando 
Published: January 2021

Autoridades presentes, directivos, docentes, personal de apoyo y alumnos de la Universidad Adventista del Plata, padres y demás familiares de graduandos, y especialmente queridos graduandos de la actual promoción.
Hace poco más de un par de siglos, quien fuera el más relevante y revolucionario pensador de la edad moderna, Emanuel Kant, expresó mediante tres preguntas lo que para él condensaba el sentido de la vida humana: ¿qué debo hacer?, ¿qué puedo saber?, ¿qué me cabe esperar?, cuestiones fundamentales de la existencia que, según él, podían resumirse en una sola: ¿qué es el hombre? La ética, la epistemología y la religión son las disciplinas encargadas de responder esas tres primeras preguntas, en tanto que de la última se ocupa la antropología.
Les propongo situarnos en el marco de estas tres preguntas kantianas para analizar desde ese lugar lo que muy posiblemente han llegado a ser ustedes al cabo de su primera formación académica universitaria, mientras están en la antesala del mundo profesional. Para ello invertiré un tanto el orden de las preguntas de Kant, abordando primeramente el tema del conocimiento.
Sin lugar a dudas, durante estos años que has pasado en la Universidad has aprendido muchas cosas, y al mismo tiempo también serás consciente de que parte de esos conocimientos han de quedar obsoletos dentro de unos años. Esto es así, no porque hayas aprendido contenidos viejos, no te asustes, seguramente están muy actualizados, sino simplemente porque el ritmo vertiginoso en que se mueve actualmente la ciencia, y la transformación del mundo como efecto de ésta, no tienen tregua y es siempre exponencialmente superior al periodo que le precede. Habrás escuchado, no pocas veces, que mientras vas pasando por la universidad, como dijera Ortega y Gasset, “es mucho más importante el camino que la posada”. Esto es, importa más el aprendizaje de métodos y procedimientos con los cuales logres obtener tus conocimientos y sepas resolver problemas, pues ello te permitirá actualizarte permanentemente y desentenderte de ideas y conceptos que van perdiendo sentido y utilidad en la vida real. Pero esto, de ninguna manera significa que debamos evitar o rechazar los contenidos, no existe aprendizaje en el vacío, sino simplemente ser capaces de separarlos entre accesorios y fundamentales, transitorios, es decir, temporales, y perdurables, o hasta incluso eternos. Semejante incorporación de conceptos te capacita para darle sentido a tu vida, a tu profesión y a tu deambular por el mundo. Ahora bien, ¿hay ideas o conceptos que hoy puedas juzgar como fundamentales y perdurables en el tiempo? ¿Te habremos preparado en ésta, tu Universidad, para que, estando a minutos de egresar de ésta, hoy alcances a discernirlos con corrección y precisión, sin temor a equivocarte? Te propongo realizar un breve ejercicio con el fin de evaluarlos y revisarlos.
Yalnızçam Uğurludağ Kış Sporları Turizm Merkezinin Potansiyeli ve Bölge Ekonomisine Etkisine Yönelik Paydaş Görüşlerinin Değerlendirilmesi
Authors: AKKUŞ Gülizar , GÜÇTEMUR Semra 
Published: January 2021

Ardahan Yalnızçam Uğurludağ bölgesi, sahip olduğu doğal çekicilik sebebiyle hem Kültür ve Turizm Koruma ve Gelişim
Bölgesi (KTKGB) ilan edilmiş hem de kış turizmi gelişim koridorunda yer bulmuştur. Türkiye turizm gelişim stratejilerinde unutulmayan bu bölge, henüz beklenen ivmeyi yakalayamamış ve bölge ekonomisine beklenen katkı sağlanamamıştır. Bu sebeple bu araştırmada destinasyon paydaşları ile kış sporları turizm merkezinin mevcut durumu, sahip olduğu potansiyel ve bölge ekonomisine katkı derecesi görüşülmüştür. Araştırmada derinlemesine görüşme tekniklerinden standartlaştırılmış açık uçlu görüşme tekniği benimsenmiştir. Görüşme soruları oluşturulurken Tuncer ve Fırat’ın (2017) çalışmasından faydalanılarak, dokuz sorudan oluşan bir görüşme formu hazırlanmıştır. Amaçlı örnekleme yöntemlerinden maksimum çeşitlilik örneklemesi seçilmiş ve örnekleme dâhil edilen tüm katılımcılar Ardahan ili turizmine yön vermede aktif rol oynayan kişilerden seçilmiştir. Araştırma kapsamında toplam 11 kamu ve özel sektör paydaşı ile yüz yüze görüşülmüştür. Görüşmeler 15-18 Ocak 2019 tarihleri arasında gerçekleştirilmiştir. Araştırma sonucunda destinasyonun yaşam eğrisini sağlıklı bir şekilde devam ettirebilmesi için faydalı olabilecek yönetsel önerilerde bulunulmuştur.