Influence of the fabrication accuracy of hot-embossed PCL scaffolds on cell growths

Polycaprolactone (PCL) is a biocompatible and biodegradable polymer widely used for the realization of 3D scaffold for tissue engineering applications. The hot embossing technique (HE) allows the obtainment of PCL scaffolds with a regular array of micro pillars on their surface. The main drawback affecting this kind of micro fabrication process is that such structural superficial details can be damaged when detaching the replica from the mold. Therefore, the present study has focused on the optimization of the HE processes through the development of an analytical model for the prediction of the demolding force as a function of temperature. This model allowed calculating the minimum demolding force to obtain regular micropillars without defects. We demonstrated that the results obtained by the analytical model agree with the experimental data. To address the importance of controlling accurately the fabricated microstructures, we seeded on the PCL scaffolds human stromal cell line (HS-5) and monocytic leukemia cell line (THP-1) to evaluate how the presence of regular or deformed pillars affect cells viability. In vitro viability results, scanning electron and fluorescence microscope imaging analysis show that the HS-5 preferentially grows on regular microstructured surfaces, while the THP-1 on irregular microstructured ones

Design and thermal performance investigation of a box cooker with flexible solar collector tubes: An experimental research

Kumar, Avnish/0000-0002-8843-1643; Saxena, Abhishek/0000-0001-9253-6774WOS: 000552898300058In recent years, solar cookers have been technologically promoted by most of the national governments as renewable and sustainable cooking system round the globe. in the present article, a solar box cooker (SBC) has been developed for fast response and uninterrupted cooking process. For this purpose, a cylindrical copper tube infused with thermal energy storage (TES) has been designed and tested under a modified SBC. Experimental study has been carried out on three different TES materials such as; grainy carbon powder, paraffin wax and specific mixture of carbon powder and paraffin. Specifically, twelve TES filled tubes have been brought into the use for experimentation at three different configurations. Results indicate that the modified cooker has better performance in terms of efficiency (53.81%), overall heat loss coefficient (5.11 W/m(2)degrees C), cooking power (68.81 W) and heat transfer coefficient (56.78 W/m(2)degrees C) in comparison with a conventional SBC and other designs using different TES materials. PCM infused tubes are low in cost and flexible to carry with SBC for outdoor cooking. It can easily be carried anywhere along with cooker. This novel configuration enables a fast response cooking with an enhanced efficiency irrespective of climatic conditions. the total cost of SBC is estimated about $39.11. (C) 2020 Elsevier Ltd. All rights reserved

Detection, location, and diagnosis of different faults in large solar PV system—a review

Over the past decade, the significance of solar photovoltaic (PV) system has played a major role due to the rapid growth in the solar PV industry. Reliability, efficiency and safety of solar. PV system can be enhanced by continuous monitoring of the system and detecting the faults if any as early as possible. Reduced real time power generation and reduced life span of the solar PV system are the results if the fault in solar PV system is found undetected. Therefore, it is mandatory to identify and locate the type of fault occurring in a solar PV system. The faults occurring in the solar PV system are classified as: physical, environmental, and electrical faults which are further classified into different types as described in this paper. Once a fault is located and detected, an appropriate diagnosis method needs to be used to rectify it. In this paper, a comprehensive review of diverse fault diagnosis techniques reported in various literature is listed and described. This paper helps the researchers to get an awareness of the various faults occurring in a solar PV system and enables them to choose a suitable diagnosis technique based on its performance metrics to rectify the fault occurring in solar PV systems

Meta-Design Approach to Environmental Building Programming for Passive Cooling of Buildings

Sustainable design practices are being disseminated all around the world, thanks to a growing interest by users, builders, and politicians in facing the impact of climate changes and the need for a more sustainable future. Nevertheless, although design practices include currently green issues and technologies, these are applied mainly in the last design phases in order to comply with local and/or national regulations and requirements (e.g. minimum values for the energy demand to be covered by renewable sources and for the envelope transmittance). Instead, to integrate sustainable technologies in an energy- and cost-effective way, it is necessary to deal with them since the earliest design phases, i.e. building programming and site analysis. Furthermore, passive and hybrid technical building systems (TBS) are dependent on the specific project context, and this is even more apparent for cooling. In fact, while the performance of passive heating TBS is mainly related to solar access and reduction of energy losses, the one of space cooling TBS depends on other variables such as internal heat gains, heat capacity, and wind environment. The paper describes a methodology to assess the energy- saving potential of passive ventilative systems in the earliest design phases. Site and climate aspects, together with definitions of needs and requirements for building programming, will be described. Results from an application of a method based on Givoni-Milne bioclimatic chart to evaluate the climate-dependent potential of passive system are reported. Criteria for spatial and technological integration of passive cooling systems are also presented