scholarly journals Designing soft/hard double network hydrogel microsphere/UHMWPE composites to promote water lubrication performance

Friction ◽  
2020 ◽  
Author(s):  
Chaobao Wang ◽  
Xiuqin Bai ◽  
Conglin Dong ◽  
Zhiwei Guo ◽  
Chengqing Yuan ◽  
...  

Abstract Several soft tissues residing in the living body have excellent hydration lubrication properties and can provide effective protection during relative motion. In order to apply this advantage of soft matters in practical applications and try to avoid its disadvantage, such as swelling and weakening in water, a design strategy of a soft/hard double network (DN) hydrogel microsphere modified ultrahigh molecular weight polyethylene (UHMWPE) composite is proposed in this study. A series of microspheres of urea-formaldehyde (UF), polyacrylamide (PAAm) hydrogel, UF/PAAm double network, and their composites were prepared. The mechanical properties, swelling, wettability, friction properties, and the lubrication mechanisms of the composites were investigated. The results show that DN microspheres can have an excellent stability and provide hydration lubrication. The performance of 75 DN-1 composite was superior to others. This finding will provide a novel strategy for the development of water-lubricated materials and have wide application in engineering fields.

Author(s):  
Yanxiang Han ◽  
Yonghong Fu

Surface texturing for improving the lubrication performance of journal bearings has been widely investigated in the last two decades. In practical applications, the misalignment of a journal bearing occurs due to the asymmetric bearing load, elastic deflection, manufacturing tolerances, and installation errors. However, there has been little discussion on the influence of grooves on the lubrication performance of misaligned bearings. In the present work, numerical predictions of lubrication performances are presented to test the influence of the grooves. Based on the JFO boundary condition, a mass conservation algorithm is implemented to automatically determine the position of oil film rupture and reformation. The load-carrying capacity, friction force, friction coefficient, and bearing moment are computed numerically. The influence of angular position of the groove is first conducted in a misaligned bearing. Subsequently, the groove depth and width are investigated with different values of [Formula: see text] and [Formula: see text] ratios, respectively.


Soft Matter ◽  
2020 ◽  
Vol 16 (28) ◽  
pp. 6582-6590 ◽  
Author(s):  
Jacob G. Turner ◽  
Jun Hyup Og ◽  
Catherine J. Murphy

Double-network hydrogels have attracted much attention because of their superior mechanical properties, which are more similar to rubbers and soft tissues than classic hydrogels.


1988 ◽  
Vol 124 ◽  
Author(s):  
Agmund K. Thorsrud

ABSTRACTMicrowave heating has for years been successfully used for some polymer applications, especially in preheating or continous vulcanization of rubber and also for crosslinking of thermosets. It may therefore seem surprising to find how little woork has been reported on the use of dielectric heating of thermoplastic resins. Certainly a major reason is that very few thermoplastics have dielectric properties making them respond to high frequency electromagnetic fields, or their response is inadequate for practical applications.Many processes could benefit from the many advantages of dielectric heating if the most suitable polymer could be made to absorb such energy. Therefore a study was undertaken to find additives which in small amounts could render virtually all polymers, especially the thermoplastic ones, responsive to microwave or radio frequency electromagnetic energy without significantly changing processing and physical properties.A series of such sensitizers was developed. Some of these are now commercially available as white, fine particle size, freeflowing powders and others are colorless liquids. Their use will depend on polymer type and application, but their common objective is to substantially increase the material's loss factor.Selected tests with difficult to process ultrahigh molecular weight polyethylene (UHWPE) and polyphenylene sulfide (PPS) proved that the sensitizers in low concentration will allow dielectric heating of unresponsive polymers with potential for important advantages in cost and quality.


Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2531
Author(s):  
Yelin Ko ◽  
Ji-seon Kim ◽  
Chi Cuong Vu ◽  
Jooyong Kim

Flexible strain sensors are receiving a great deal of interest owing to their prospective applications in monitoring various human activities. Among various efforts to enhance the sensitivity of strain sensors, pre-crack generation has been well explored for elastic polymers but rarely on textile substrates. Herein, a highly sensitive textile-based strain sensor was fabricated via a dip-coat-stretch approach: a polyester woven elastic band was dipped into ink containing single-walled carbon nanotubes coated with silver paste and pre-stretched to generate prebuilt cracks on the surface. Our sensor demonstrated outstanding sensitivity (a gauge factor of up to 3550 within a strain range of 1.5–5%), high stability and durability, and low hysteresis. The high performance of this sensor is attributable to the excellent elasticity and woven structure of the fabric substrate, effectively generating and propagating the prebuilt cracks. The strain sensor integrated into firefighting gloves detected detailed finger angles and cyclic finger motions, demonstrating its capability for subtle human motion monitoring. It is also noteworthy that this novel strategy is a very quick, straightforward, and scalable method of fabricating strain sensors, which is extremely beneficial for practical applications.


1968 ◽  
Vol 54 (4) ◽  
pp. 267-289
Author(s):  
Bruno Damascelli ◽  
Angelo Lattuada ◽  
Renato Musumeci ◽  
Aldo Severini

Ultrasound scanning of the soft tissues has been used increasingly at clinical level for some years now, especially for investigating abdominal organs and abdominopelvic space-occupying lesions, whose intrinsic structure they delineate. This paper deals with the practical applications of ultrasound and compares the information it supplies with that supplied by the simpler and least traumatic radiologic investigations in 60 cases of abdominopelvic swellings. In all the patients ultrasound demonstrated space-occupying lesions and in 52 cases specified whether the mass was cystic or solid, whether a cyst was uni- or multilocular and whether a solid mass was homogeneous or not. In this series only one multilocular ovarian cystocarcinoma was mistaken for a solid mass. Compared with routine X-ray investigations, the ultrasound findings proved to be superfluous in 33 cases and contributory in 27. The latter were mainly utero-ovarian masses, hepatomegalies, swellings of nonfunctioning kidneys or gallbladders and serous cysts.


mSystems ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Ursula M. McCormack ◽  
Tânia Curião ◽  
Toby Wilkinson ◽  
Barbara U. Metzler-Zebeli ◽  
Henry Reyer ◽  
...  

ABSTRACT Previous studies suggest a link between intestinal microbiota and porcine feed efficiency (FE). Therefore, we investigated whether fecal microbiota transplantation (FMT) in sows and/or neonatal offspring, using inocula derived from highly feed-efficient pigs, could improve offspring FE. Pregnant sows were assigned to control or FMT treatments and the subsequent offspring to control treatment, FMT once (at birth), or FMT four times (between birth and weaning). FMT altered sow fecal and colostrum microbiota compositions and resulted in lighter offspring body weight at 70 and 155 days of age when administered to sows and/or offspring. This was accompanied by FMT-associated changes within the offspring’s intestinal microbiota, mostly in the ileum. These included transiently higher fecal bacterial diversity and load and numerous compositional differences at the phylum and genus levels (e.g., Spirochaetes and Bacteroidetes at high relative abundances and mostly members of Clostridia , respectively), as well as differences in the abundances of predicted bacterial pathways. In addition, intestinal morphology was negatively impacted, duodenal gene expression altered, and serum protein and cholesterol concentrations reduced due to FMT in sows and/or offspring. Taken together, the results suggest poorer absorptive capacity and intestinal health, most likely explaining the reduced body weight. An additive effect of FMT in sows and offspring also occurred for some parameters. Although these findings have negative implications for the practical use of the FMT regime used here for improving FE in pigs, they nonetheless demonstrate the enormous impact of early-life intestinal microbiota on the host phenotype. IMPORTANCE Here, for the first time, we investigate FMT as a novel strategy to modulate the porcine intestinal microbiota in an attempt to improve FE in pigs. However, reprogramming the maternal and/or offspring microbiome by using fecal transplants derived from highly feed-efficient pigs did not recapitulate the highly efficient phenotype in the offspring and, in fact, had detrimental effects on lifetime growth. Although these findings may not be wholly attributable to microbiota transplantation, as antibiotic and purgative were also part of the regime in sows, similar effects were also seen in offspring, in which these interventions were not used. Nonetheless, additional work is needed to unravel the effects of each component of the FMT regime and to provide additional mechanistic insights. This may lead to the development of an FMT procedure with practical applications for the improvement of FE in pigs, which could in turn improve the profitability of pig production.


Author(s):  
Xinzhen Ji ◽  
Zhuangzhuang Ma ◽  
Xu Chen ◽  
Di Wu ◽  
Yongtao Tian ◽  
...  

Abstract Recently, non-toxic alternatives to lead-halide perovskites have been greatly sought after in optoelectronics applications. Deep-blue luminescent material is mainly required for fabricating white light source and expanding the color gamut of full-color displays. However, the synthesis of high-performance lead-free perovskite films with efficient blue emission is still a critical challenge currently, limiting their further practical applications. Here, a novel strategy is reported to prepare non-toxic and deep-blue-emitting K2CuBr3 nanocrystalline films by introducing polymer poly(methyl methacrylate) (PMMA) additives into the anti-solvent. It is found that the PMMA additives could effectively reduce the grain size and improve the crystallinity of K2CuBr3 films, resulting in an enhanced radiative recombination by defect passivation and confinement of excitons in the nanograins. As a result, the PMMA-treated K2CuBr3 films achieve a bright deep-blue light with color coordinates at (0.155, 0.042), and the photoluminescence quantum yield obtained is about 3.3 times that of the pristine sample. Moreover, the treated K2CuBr3 films exhibit a substantially enhanced stability under harsh environmental conditions, maintaining >70% of their initial performances in high humidity environment (50‒70% humidity, 190 h) or under uninterrupted ultraviolet light radiation (254 nm, 3.4 mW/cm2, 150 h). These findings pave a promising strategy for achieving efficient and stable deep-blue metal halide films, showing their potential applications in optoelectronic devices.


Author(s):  
Guo-Yang Li ◽  
Yanping Cao

Ultrasound elastography enables in vivo measurement of the mechanical properties of living soft tissues in a non-destructive and non-invasive manner and has attracted considerable interest for clinical use in recent years. Continuum mechanics plays an essential role in understanding and improving ultrasound-based elastography methods and is the main focus of this review. In particular, the mechanics theories involved in both static and dynamic elastography methods are surveyed. They may help understand the challenges in and opportunities for the practical applications of various ultrasound elastography methods to characterize the linear elastic, viscoelastic, anisotropic elastic and hyperelastic properties of both bulk and thin-walled soft materials, especially the in vivo characterization of biological soft tissues.


Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 952 ◽  
Author(s):  
Zhanxin Jing ◽  
Aixing Xu ◽  
Yan-Qiu Liang ◽  
Zhaoxia Zhang ◽  
Chuanming Yu ◽  
...  

We proposed a novel strategy in the fabrication of biodegradable poly(acrylic acid-co-acrylamide)/poly(vinyl alcohol) (P(AAc-co-Am)/PVA) double network (DN) hydrogels with good mechanical and self-healing properties. In the DN hydrogel system, P(AAc-co-Am) polymers form a network through the ionic coordinates between –COO– and Fe3+ and hydrogen bonding between –COOH and –CONH2, while another network is fabricated by the complexation between PVA and borax. The influences of the composition on the rheological behaviors and mechanical properties of the synthesized DN hydrogels were investigated. The rheological measurements revealed that the viscoelasticity and stiffness of the P(AAc-co-Am)/PVA DN hydrogels increase as the acrylamide and Fe3+ concentrations increase. At 0.05 mmol of Fe3+ and 50% of acrylamide, tensile strength and elongation at break of P(AAc-co-Am)/PVA DN hydrogels could reach 329.5 KPa and 12.9 mm/mm, respectively. These properties arise from the dynamic reversible bonds existed in the P(AAc-co-Am)/PVA DN hydrogels. These reversible bonds also give good self-healing properties, and the maximum self-healing efficiency of P(AAc-co-Am)/PVA DN hydrogels is up to 96.4%. The degradation test of synthesized DN hydrogels was also conducted under simulated physiological conditions and the weight loss could reach 74% in the simulated intestinal fluid. According to the results presented here, the synthesized P(AAc-co-Am)/PVA DN hydrogels have a potential application prospect in various biomedical fields.


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