Metallic nanoparticles are a type of nanomaterial synthesized from metallic precursors. Due to their unique physiochemical, electrical, and optical properties, metallic nanoparticles are widely studied and applied in various areas such as medicine, electronics, and heat transfer systems. However, conventional synthesis methods to produce metallic nanoparticles face challenges such as instability and environmental concerns, prompting the exploration of greener synthesis methods. Green synthesis uses natural resources like plants and algae as reducing agents, offering a more environmentally friendly approach for the synthesis of metallic nanoparticles. These green-synthesized metallic nanoparticles can enhance heat transfer by becoming part of nanofluids (NFs), which are colloidal mixtures of NPs in a fluid base. NFs, employed for heat transfer. As a result, it is essential to characterize the NFs regarding wettability, viscosity, and thermal conductivity. The results of the spectrophotometer confirmed the green synthesis of NPs, and it was observed that the increase in NP concentration impacted the contact angle, improving the ability to wet. The thermal conductivity is also modified, with an improvement of 11.3% compared to distilled water, without a significant increase in fluid viscosity.

Conventional methods for synthesizing metallic nanoparticles face challenges such as instability and environmental concerns. Therefore, new, simpler, and more eco-friendly methods are being explored. In this context, the study reports a green synthesis process to produce magnetic iron oxide nanoparticles using an aqueous extract of the alga Chlorella vulgaris. This process leverages natural resources to create a sustainable nanofluid known as green nanofluid. To evaluate the characteristics of this nanofluid, experimental measurements of wettability, viscosity, thermal conductivity, and qualitative stability analysis were conducted. An experimental setup consisting of a heat exchanger made of polydimethylsiloxane (PDMS) was used to assess the thermal performance and the results were compared to theoretical equations and numerical simulation. Additionally, thermographic imaging of temperature gradients as the fluids passed over the heated surface of the serpentine channel were made. The main findings confirmed that the nanofluid was more stable than that obtained by traditional methods and had a more uniform temperature distribution over the heat exchanger. The higher concentration exhibited superior thermal performance compared to DI-Water. Moreover, the green nanofluid was used at a weight concentration of 0.1 wt%, provided thermal performance results of nearly 4.5% superior to those estimated by the numerical model and 6.4% higher than those experimentally obtained with the base fluid, respectively. Finally, the results obtained for the nanofluid also showed an average increase of around 5% in the viscosity of the base fluid, with a more significant sedimentation at a concentration of 0.1 wt%.

Polydimethylsiloxane (PDMS) exhibits unique properties that make it essential in various biomedical applications. This systematic review critically examines current research on PDMS surface modification methods, focusing on enhancing its biocompatibility and functionality. Following a rigorous selection process aligned with PRISMA guidelines, 83 relevant studies published between 2013 and July 2024, out of 938 initially identified publications, were analyzed for key insights. The review is structured in two main sections: the first focuses on the diverse PDMS surface modification techniques, including plasma treatments, ultraviolet and thermal treatments, polymer adsorption, surfactant applications, and surface modification through grafting and functionalization. The second section highlights various biomedical applications of PDMS. By elucidating the outcomes of both various surface modification approaches and their applications, this review provides insights into the potential of PDMS to address important issues in clinical and biomedical research, thus paving the way for further advancements in the field.

Thermal regulation has assumed a central role in space expeditions ever since the inception of Sputnik-1 in 1957. Throughout the years, numerous techniques have been developed to regulate temperatures in spacecraft and space habitats. Initially, passive systems like heat shields and thermal linings were employed, while newer missions embrace active cooling using fluids like ammonia and water. With significant advancements in lunar exploration, thermal management systems have been integrated to ensure effective heat protection and dissipation. Experiments carried out in drop towers, parabolic flights, sounding rockets, and aboard the International Space Station (ISS) have yielded valuable insights into the physics of fluids, pool boiling, boiling in two-phase flow, and cooling phenomena. However, conducting tests in microgravity conditions can lead to lower performances, and accurate numerical simulations remain a challenge. At present, various organizations are conducting research to drive progress in thermal management and enhance the technology of space devices. This review describes the most recent advances in two-phase fluid experiments in microgravity. Furthermore, the major challenges that persist in this field are presented and discussed, along with observations on trends and possibilities for the future of thermal control in space. This review attempts to be a relevant guide for future research and developments on thermal control in space.

One of the most popular materials for creating bio models and microfluidic devices is polydimethylsiloxane (PDMS). Recently, a unique class of devices called organs-on-a-chip (OoC) was created by fusing cell cultures with microfluidic devices. To make it easier to investigate both healthy and pathological conditions, these devices replicate the micro physiological characteristics of the human body. OoCs are most manufactured using PDMS because of its mechanical, chemical, and biocompatible qualities. However, the hydrophobic characteristics of PDMS results in several disadvantages, such as increased flow resistance, nonspecific molecular adhesion, and reduced biochemical test specificity. Additionally, because of the greater flow resistance imposed by the hydrophobicity of the microchannel walls, external flow control methods, like syringe pumps are needed in both OoC and microfluidic devices. Applying oxygen and air plasma treatment to the surface is the most often used method of increasing the PDMS surface wettability. The current study provides an insight regarding the duration and efficacy of different surface methods for PDMS surface modification: oxygen, air, and argon plasma, ultra-violet-Ozone treatment and oxygen plasma followed by immersion in polyethylene glycol, Pluronic F-127, and polyethylene oxide.