scholarly journals Rapid synchronized fabrication of vascularized thermosets and composites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mayank Garg ◽  
Jia En Aw ◽  
Xiang Zhang ◽  
Polette J. Centellas ◽  
Leon M. Dean ◽  
...  

AbstractBioinspired vascular networks transport heat and mass in hydrogels, microfluidic devices, self-healing and self-cooling structures, filters, and flow batteries. Lengthy, multistep fabrication processes involving solvents, external heat, and vacuum hinder large-scale application of vascular networks in structural materials. Here, we report the rapid (seconds to minutes), scalable, and synchronized fabrication of vascular thermosets and fiber-reinforced composites under ambient conditions. The exothermic frontal polymerization (FP) of a liquid or gelled resin facilitates coordinated depolymerization of an embedded sacrificial template to create host structures with high-fidelity interconnected microchannels. The chemical energy released during matrix polymerization eliminates the need for a sustained external heat source and greatly reduces external energy consumption for processing. Programming the rate of depolymerization of the sacrificial thermoplastic to match the kinetics of FP has the potential to significantly expedite the fabrication of vascular structures with extended lifetimes, microreactors, and imaging phantoms for understanding capillary flow in biological systems.

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 585
Author(s):  
Ariel Ma ◽  
Jian Yu ◽  
William Uspal

Natural evaporation has recently come under consideration as a viable source of renewable energy. Demonstrations of the validity of the concept have been reported for devices incorporating carbon-based nanocomposite materials. In this study, we investigated the possibility of using polymer thin films to generate electricity from natural evaporation. We considered a polymeric system based on polyvinylidene fluoride (PVDF). Porous PVDF films were created by incorporating a variety of nanocomposite materials into the polymer structure through a simple mixing procedure. Three nanocomposite materials were considered: carbon nanotubes, graphene oxide, and silica. The evaporation-induced electricity generation was confirmed experimentally under various ambient conditions. Among the nanocomposite materials considered, mesoporous silica (SBA-15) was found to outperform the other two materials in terms of open-circuit voltage, and graphene oxide generated the highest short-circuit current. It was found that the nanocomposite material content in the PVDF film plays an important role: on the one hand, if particles are too few in number, the number of channels will be insufficient to support a strong capillary flow; on the other hand, an excessive number of particles will suppress the flow due to excessive water absorption underneath the surface. We show that the device can be modeled as a simple circuit powered by a current source with excellent agreement between the theoretical predictions and experimental data.


Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 520 ◽  
Author(s):  
Jia Zhu ◽  
Guanzhou Lin ◽  
Meizhang Wu ◽  
Zhuojie Chen ◽  
Peimin Lu ◽  
...  

Technology transfer from laboratory into practical application needs to meet the demands of economic viability and operational simplicity. This paper reports a simple and convenient strategy to fabricate large-scale and ultrasensitive surface-enhanced Raman scattering (SERS) substrates. In this strategy, no toxic chemicals or sophisticated instruments are required to fabricate the SERS substrates. On one hand, Ag nanoparticles (NPs) with relatively uniform size were synthesized using the modified Tollens method, which employs an ultra-low concentration of Ag+ and excessive amounts of glucose as a reducing agent. On the other hand, when a drop of the colloidal Ag NPs dries on a horizontal solid surface, the droplet becomes ropy, turns into a layered structure under gravity, and hardens. During evaporation, capillary flow was burdened by viscidity resistance from the ropy glucose solution. Thus, the coffee-ring effect is eliminated, leading to a uniform deposition of Ag NPs. With this method, flat Ag NPs-based SERS active films were formed in array-well plates defined by hole-shaped polydimethylsiloxane (PDMS) structures bonded on glass substrates, which were made for convenient detection. The strong SERS activity of these substrates allowed us to reach detection limits down to 10−14 M of Rhodamine 6 G and 10−10 M of thiram (pesticide).


2016 ◽  
Vol 107 ◽  
pp. 125-137 ◽  
Author(s):  
Kim Van Tittelboom ◽  
Jianyun Wang ◽  
Maria Araújo ◽  
Didier Snoeck ◽  
Elke Gruyaert ◽  
...  
Keyword(s):  

2006 ◽  
Vol 75 (4) ◽  
pp. 533-540 ◽  
Author(s):  
Ž. Pavičić ◽  
T. Balenović ◽  
H. Valpotić ◽  
A. Tofant ◽  
M. Popović ◽  
...  

Microbiological composition of air, as a factor of ambient conditions in animal facilities can significantly influence performance, health and animal welfare in the swine production. The aim of this investigation was to determine, by monitoring primary microclimatic conditions, the possible association of the number of fattening pigs per unit of housing space with species diversity and number of airborne microorganisms. The research was conducted at a fattening and finishing facility of 450 m2 (equipped with 44 pens designed for 10 animals each) with low-pressure ventilation in three different trials. The first trial was conducted during the autumn-winter period with the capacity of 440 animals (0.7 m2 of pen area per fattening pig), the second trial was conducted during the winter-spring period with 356 animals (0.8 m2 of pen area per fattening pig), and the third trial was conducted during the spring-summer period with 312 animals (1.0 m2 of pen area per fattening pig). The air samples for isolation of fungi and mesophilic, haemolytic, and coliform bacteria were taken and microclimatic conditions were monitored during each trial at the same consecutive weekly periods. According to the data obtained from all trials, the total number of bacteria and fungi did not exceed 104 and 103 CFU per m3, respectively. The most numerous were gram-positive bacteria, followed by gram-negative bacteria and fungi. The total number of airborne microorganisms correlates significantly (at p < 0.05) with porcine housing density. These data may be useful for the assessment of housing density at fattening facilities that will not compromise swine health and welfare regarding the microbiological air quality, and thus may contribute to the implementation of optimal rearing conditions in large-scale animal producing units.


2021 ◽  
Author(s):  
ABM B. Alam

Network Survivability is a critical issue in telecommunications network due to increasing dependence of the society on communication systems. Fast restoration from a network failure is an important challenge that deserves attention. This thesis addresses an optimal link capacity design problem for survivable asynchronous transfer mode (ATM) network based on the link restoration strategy. Given a projected traffic demands and the network topology, capacity and flow assignment are jointly optimized to yield the optimal capacity placement. The problem is formulated as large-scale nonlinear programming and is solved using a specific type of Lagrange method (so called Separable Augmented Lagrangian Algorithm or SALA for short). Several networks with diverse topological characteristics are used in the experiments to validate our proposed novel model, using capacity installation cost, routing cost, total network cost, used capacity and required CPU time, as performance metrics. Link restoration strategy is compared against global reconfiguration strategy using these performance metrics.


2014 ◽  
Vol 553 ◽  
pp. 3-9 ◽  
Author(s):  
Hai Fei Zhan ◽  
Ye Wei ◽  
Yuan Tong Gu

Doping as one of the popular methods to manipulate the properties of nanomaterials has received extensive application in deriving different types of graphene derivates, while the understanding of the resonance properties of dopant graphene is still lacking in literature. Based on the large-scale molecular dynamics simulation, reactive empirical bond order potential, as well as the tersoff potential, the resonance properties of N-doped graphene were studied. The studied samples were established according to previous experiments with the N atom’s percentage ranging from 0.38%-2.93%, including three types of N dopant locations, i.e., graphitic N, pyrrolic N and pyridinic N. It is found that different percentages of N-dopant exert different influence to the resonance properties of the graphene, while the amount of N-dopant is not the only factor that determines its impact. For all the considered cases, a relative large percentage of N-dopant (2.65% graphitic N-dopant) is observed to introduce significant influence to the profile of the external energy, and thus lead to an extremely low Q-factor comparing with that of the pristine graphene. The most striking finding is that the natural frequency of the defective graphene with N-dopant’s percentage higher than 0.89% appears larger than its pristine counterpart. For the perfect graphene, the N-dopant shows larger influence to its natural frequency. This study will enrich the current understanding of the influence of dopants on graphene, which will eventually shed lights on the design of different molecules-doped graphene sheet.


2021 ◽  
Author(s):  
Moataz Dowaidar

This review carefully reviewed recent polydopamine (PDA) research, including targeted therapy and cancer synergistic medications. Recent breakthroughs in photothermal treatment coupled with complex therapies such as gene therapy, radiation, and especially immunotherapy were highlighted. Due to their exceptional biocompatibility, degradability, low toxicity and high photothermal conversion efficiency, facile oxidative self-polymerization of dopamine can create PDA and serve as an excellent nanocarrier or photothermal cancer treatment agent. Due to its high adhesive capacity, PDA may be easily functionalized with a range of nanomaterials for synergistic cancer therapy, in addition to its exceptional photothermal effects. Although PDA-based multifunctional nanoplatforms have gained interest for synergistic cancer therapy, such as chemo-photothermal treatment and photodynamic-photothermal treatment, discovering novel uses for PDA remains tough. First, despite its easy and mild process of synthesis, large-scale synthesis with uniform size and thickness is challenging owing to the absence of consistent quality control standards. Second, due to the strong adhesive properties of PDA, multifunctional nanoplatforms are prone to aggregating in a solution. Third, to improve PDA's clinical application, its safety should be fully researched. Before being deployed in clinical settings, PDA-based multifunctional systems need additional research. A PDA-based multifunctional platform for better synergistic cancer treatment is a forward-looking strategy. In particular, PDA-based immunotherapy systems will remain a research center.Besides immunotherapy, in recent years, the integration of cancer diagnosis and treatment has gained a lot of publicity. Polyphenols have been proven to suppress tumor development and interact with metals such as Fe3+, Pt4+, Cu2+, etc (MPNs). MPNs are biocompatible, functional, pH-responsive and can escape endosomes. PDA has the potential to develop MPNs with contrasting magnetic resonance agents like gadolinium due to the enormous quantity of catechol groups on its surface, allowing magnetic resonance imaging. Polyphenols also have tumor-inhibiting effects, and PDA's photothermal activity can ablate tumors. Consequently, PDA-based MPNs might be a promising way to integrate diagnosis and treatment. Moreover, polydopamine can crosslink acrylamide and other polymers to form anticancer and antibacterial hydrogels. Increasing the stickiness of polydopamine hydrogels is now underway, paving the path for self-adhesive bioelectronics hydrogels. Bioelectron self-adhesion and other capabilities such as self-healing, transparency, and bacterio-toxicity may be supplied to polydopamine hydrogels by altering phenolquinone's redox process. A prospective future trend is using self-adhesive polydopamine hydrogels with current bioelectronic materials. We think that polydopamine hydrogels will eventually advance from skin patches to implantable integrated bioelectronics.


Nano Letters ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 6706-6711
Author(s):  
Eun-Ji Gwak ◽  
Hansol Jeon ◽  
Eunji Song ◽  
Ju-Young Kim

2020 ◽  
Vol 8 (40) ◽  
pp. 14083-14091
Author(s):  
Ji-Dong Liu ◽  
Xiang-Yun Du ◽  
Cai-Feng Wang ◽  
Qing Li ◽  
Su Chen

Robust and self-healing polymeric gels based on triple non-covalent interactions have been constructed for generation of a new self-healing thermoresponsive smart window.


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