Prescribing patterns in growing tubular soft matter by initial residual stress.

Initial residual stress is omnipresent in biological tissues and soft matter, and can affect growth-induced pattern selection significantly. Here we demonstrate this effect experimentally by letting soft tubes grow in the presence or absence of initial residual stress and by observing different growth pattern evolutions. These experiments motivate us to model the mechanisms at play when a growing bilayer tubular organ spontaneously displays buckling patterns on its inner surface. We demonstrate that not only differential growth, geometry and elasticity, but also initial residual stress distribution, exert a notable influence on these pattern phenomena. Prescribing an initial residual stress distribution offers an alternative or a more effective way to implement pattern selection for growable bio-tissues or soft matter. The results also show promise for the design of 4D bio-mimic printing protocols or for controlling hydrogel actuators.

A versatile hydrogel network-repairing strategy achieved by the covalent-like hydrogen bond interaction.

Hydrogen bond engineering is widely exploited to impart stretchability, toughness, and self-healing capability to hydrogels. However, the enhancement effect of conventional hydrogen bonds is severely limited by their weak interaction strength. In nature, some organisms tolerate extreme conditions due to the strong hydrogen bond interactions induced by trehalose. Here, we report a trehalose network-repairing strategy achieved by the covalent-like hydrogen bonding interactions to improve the hydrogels' mechanical properties while simultaneously enabling them to tolerate extreme environmental conditions and retain synthetic simplicity, which proves to be useful for various kinds of hydrogels. The mechanical properties of trehalose-modified hydrogels including strength, stretchability, and fracture toughness are substantially enhanced under a wide range of temperatures. After dehydration, the modified hydrogels maintain their hyperelasticity and functions, while the unmodified hydrogels collapse. This strategy provides a versatile methodology for synthesizing extremotolerant, highly stretchable, and tough hydrogels, which expand their potential applications to various conditions.

A Mechanically Robust and Versatile Liquid-Free Ionic Conductive Elastomer.

Soft ionic conductors, such as hydrogels and ionogels, have enabled stretchable and transparent ionotronics, but they suffer from key limitations inherent to the liquid components, which may leak and evaporate. Here, novel liquid-free ionic conductive elastomers (ICE) that are copolymer networks hosting lithium cations and associated anions via lithium bonds and hydrogen bonds are demonstrated, such that they are intrinsically immune from leakage and evaporation. The ICEs show extraordinary mechanical versatility including excellent stretchability, high strength and toughness, self-healing, quick self-recovery, and 3D-printability. More intriguingly, the ICEs can defeat the conflict of strength versus toughness-a compromise well recognized in mechanics and material science-and simultaneously overcome the conflict between ionic conductivity and mechanical properties, which is common for ionogels. Several liquid-free ionotronics based on the ICE are further developed, including resistive force sensors, multifunctional ionic skins, and triboelectric nanogenerators (TENGs), which are not subject to limitations of previous gel-based devices, such as leakage, evaporation, and weak hydrogel-elastomer interfaces. Also, the 3D printability of the ICEs is demonstrated by printing a series of structures with fine features. The findings offer promise for a variety of ionotronics requiring environmental stability and durability.

Prevalence and characteristics of extended-spectrum ß-lactamases-producing Escherichia coli from broiler chickens at different day-age.

Commensal Escherichia coli from the poultries have been considered as reservoirs of extended-spectrum ß-lactamases (ESBL)-encoding genes. Between May 2018 and March 2019, a total of 340 E. coli isolates were obtained from apparently healthy broiler chickens from 20 to 40 D old, distributed in 17 small-scale commercial farms. Finally, 45 isolates (8 from 20-day-old broiler chickens, 14 from 30-day-old ones, and 23 from 40-day-old ones) were identified as ESBL producers, which were further investigated to shed light on the virulence gene profiles, phylogenetic groups, and multilocus sequence types and to detect the ESBL plasmid-mediated quinolone resistance determinant (PMQR) genes as well as the mutations in the quinolone resistance-determining regions (QRDR) of gyrA and parC. Molecular analysis showed that phylogenic group A and B1 accounted for 66.7% of the ESBL producers. The overall occurrence of virulence genes ranged from 5.1% (cva) to 86.7% (papC). Twenty (44.4%) ESBL producers were considered as biofilm producers with moderate or heavy biofilm formation. The most predominant specific CTX-M subtype was blaCTX-M-14 (n = 19), followed by blaCTX-M-9 (n = 17), blaCTX-M-55 (n = 9), blaCTX-M-15 (n = 6), blaCTX-M-1 (n = 5), and blaCTX-M-65 (n = 4). Additionally, PMQR genes were identified in 86.7% of ESBL producers, qnrS (n = 21) was the most dominant PMQR gene, followed by the aac(6')-Ib-cr (n = 15), qnrB (n = 12), and qnrA (n = 9), and all of them co-expressed with ß-lactamase genes. All PMQR-positive isolates harbored simultaneously at least 1 mutation in the QRDR of gyrA and parC. Forty-five ESBL producers were assigned to 33 sequence types, and the most frequent sequence types (STs) was ST10 (n = 5) and followed by ST95 (n = 3). Additionally, ST302, ST88, ST410, ST187, and ST23 were represented by 2 ESBL producers, respectively, and the remaining ones exhibited diverse ST. Moreover, the prevalence of ESBL producers, the biofilm-forming ability, and the occurrence of the QRDR mutations among the E. coli isolates were characterized by gradually increased with advancing age of broiler chickens.

Dual pH-Responsive Hydrogel Actuator for Lipophilic Drug Delivery.

As one of the most promising drug delivery carriers, hydrogels have received considerable attention in recent years. Many previous efforts have focused on diffusion-controlled release, which allows hydrogels to load and release drugs in vitro and/or in vivo. However, it hardly applies to lipophilic drug delivery due to their poor compatibility with hydrogels. Herein, we propose a novel method for lipophilic drug release based on a dual pH-responsive hydrogel actuator. Specifically, the drug is encapsulated and can be released by a dual pH-controlled capsule switch. Inspired by the deformation mechanism of Drosera leaves, we fabricate the capsule switch with a double-layer structure that is made of two kinds of pH-responsive hydrogels. Two layers are covalently bonded together through silane coupling agents. They can bend collaboratively in a basic or acidic environment to achieve the "turn on" motion of the capsule switch. By incorporating an array of parallel elastomer stripes on one side of the hydrogel bilayer, various motions (e.g., bending, twisting, and rolling) of the hydrogel bilayer actuator were achieved. We conducted an in vitro lipophilic drug release test. The feasibility of this new drug release method is verified. We believe this dual pH-responsive actuator-controlled drug release method may shed light on the possibilities of various drug delivery systems.

Impacts of high-intensity interval training on physical fitness in handball / Impactos do treinamento intervalado de alta intensidade sobre a aptidão física no handebol / Impactos del entrenamiento por intervalos de alta intensidad en la aptitud física en el balonmano

ABSTRACT Introduction: Handball is a competitive sport with high demands on the physical fitness of its athletes, being physical exercise demands continuous quality improvement of its practitioners. Objective: Explore the effect of high-intensity interval training on physical fitness in young handball players. Methods: In this paper, 46 young handball players were randomly selected for the research. The volunteers were randomly divided into two different groups: the experimental group and the control group. The control group mainly performed regular physical exercises. While the experimental group performed a protocol with high-intensity interval training. Both groups underwent a basic fitness test before and after the experiment. All experimental data were statistically analyzed and discussed. Results: After 12 weeks of experimental intervention, the experimental group showed significant differences in three items, namely reentry sensitivity, vertical jump, and long position jump (P<0.05). In the comparison between the groups, the scores in straight thrust and long jump were also significant (P<0.05). Conclusion: High-intensity interval training proved effective in improving young handball players' physical fitness. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: O handebol é um esporte competitivo que tem altas exigências quanto à aptidão física de seus atletas sendo o exercício físico uma demanda para a melhoria contínua da qualidade de seus praticantes. Objetivo: Explorar o efeito do treinamento intervalado de alta intensidade sobre a aptidão física em jovens jogadores de handebol. Métodos: Neste artigo, 46 jovens jogadores de handebol foram aleatoriamente selecionados para a pesquisa. Os voluntários foram divididos aleatoriamente em dois grupos diferentes: o grupo experimental e o grupo de controle. O grupo de controle realizou principalmente exercícios físicos regulares. Enquanto o grupo experimental realizou um protocolo com treinamentos intervalados de alta intensidade. Ambos os grupos foram submetidos a um teste de aptidão básica antes e depois do experimento. Todos os dados experimentais foram analisados estatisticamente e discutidos. Resultados: Após 12 semanas de intervenção experimental, o grupo experimental mostrou diferenças significativas em três itens, a saber: sensibilidade de reentrada, salto vertical e salto em posição longa (P<0,05). Na comparação entre os grupos, as pontuações no impulso reto e no salto à distância também foram significativas (P<0,05). Conclusão: O treinamento intervalado de alta intensidade mostrou-se eficaz para o aprimoramento da aptidão física dos jovens jogadores de handebol. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: El balonmano es un deporte de competición que tiene una alta exigencia en la condición física de sus deportistas, siendo el ejercicio físico una exigencia para la mejora continua de la calidad de sus practicantes. Objetivo: Explorar el efecto del entrenamiento por intervalos de alta intensidad sobre la aptitud física de jóvenes jugadores de balonmano. Métodos: En este trabajo, 46 jóvenes jugadores de balonmano fueron seleccionados al azar para la investigación. Los voluntarios fueron divididos aleatoriamente en dos grupos diferentes: el grupo experimental y el grupo de control. El grupo de control realizó principalmente ejercicios físicos regulares. Mientras que el grupo experimental realizó un protocolo con entrenamiento de intervalos de alta intensidad. Ambos grupos se sometieron a una prueba de aptitud física básica antes y después del experimento. Todos los datos experimentales se analizaron y discutieron estadísticamente. Resultados: Tras 12 semanas de intervención experimental, el grupo experimental mostró diferencias significativas en tres ítems, a saber, la sensibilidad de reentrada, el salto vertical y el salto en posición larga (P<0,05). En la comparación entre los grupos, las puntuaciones en empuje recto y salto de longitud también fueron significativas (P<0,05). Conclusión: El entrenamiento interválico de alta intensidad demostró ser eficaz para la mejora de la condición física de los jóvenes jugadores de balonmano. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Soft Display Using Photonic Crystals on Dielectric Elastomers.

Soft display has been intensively studied in recent years in the wake of rapid development of a variety of soft materials. The currently existing solutions for translating the traditional hard display into the more convenient soft display mainly include light-emitting diodes, liquid crystals, quantum dots, and phosphors. The desired soft display should take the advantages of facile fabrication processes and cheap raw materials. Besides, the device should be colorful, nontoxic, and not only flexible but also stretchable. However, the foregoing devices may not own all of the desired features. Here, a new type of soft display, which consists of dielectric elastomer and photonic crystals that cover all of the features mentioned above and can achieve the color change dynamically and in situ, is reported. In addition to the above features, the angle-dependent characteristic and the excellent mechanical reliability make it a great candidate for the next generation of soft display. Finally, the vast applications of the present concept in a variety of fields are also prospected.