Due to the expansion of the use of powder bed fusion metal additive technologies in the medical field, especially for the realization of dental prostheses, in this paper, the authors propose a comparative experimental study of the mechanical characteristics and the state of their microscale surfaces. The comparison was made from material considerations starting from two dental alloys commonly used to realize dental prostheses: Ni-Cr and Co-Cr, but also technologies for obtaining selective laser melting (SLM) and conventional casting. In addition, to compare the performances with the classical casting technology, for the dental prostheses obtained through SLM, the post-processing stage in which they are in a preliminary finishing and polished state was considered. Therefore, for the determination of important mechanical characteristics and the comparative study of dental prostheses, the indentation test was used, after which the hardness, penetration depths (maximum, permanent, and contact depth), contact stiffness, and contact surface were established, and for the determination of the microtopography of the surfaces, atomic force microscopy (AFM) was used, obtaining the local areal roughness parameters at the miniaturized scale—surface average roughness, root-mean-square roughness (RMS), and peak-to-peak values. Following the research carried out, several interesting conclusions were drawn, and the superiority of the SLM technology over the classic casting method for the production of dental prostheses in terms of some mechanical properties was highlighted. At the same time, the degree of finishing of dental prostheses made by SLM has a significant impact on the mechanical characteristics and especially the local roughness parameters on a miniaturized scale, and if we consider the same degree of finishing, no major differences are observed in the roughness parameters of the surfaces of the prostheses produced by different technologies.

Corrugated cardboard is widely used for packaging due to its sturdiness and lightweight properties. However, its ability to withstand lateral forces during handling, transportation, and storage is critical for maintaining its structural integrity. In this study, the problem of understanding and quantifying the strain experienced by corrugated cardboard boxes under shear stresses at various points in their lifecycle is addressed. Specifically, a precise methodology for testing shear stresses was developed and validated, enhancing the understanding of the material’s behaviour. Several key problems are addressed in this research, including the quantification of the amount of strain experienced by cardboard boxes from a warehouse to the final delivery, the development of a reliable testing methodology to measure shear stresses, and the understanding of the mechanical behaviour and structural integrity of corrugated cardboard under these conditions. It is anticipated that the findings will improve the design and durability of corrugated cardboard packaging, ensuring better performance during transportation and storage. This research contributes to the optimisation of logistics, the improvement of packaging quality, and the support of sustainable development by enhancing the reuse and recyclability of corrugated cardboard.

In this work, three hydraulic fluids—a paraffinic mineral hydraulic oil (H46) and two biodegradable oils (HETG46—hydraulic oil based on natural esters and HF-E46—hydraulic oil based on synthetic esters derived from fatty acids extracted from vegetable oils)—were studied in both fresh and thermally degraded states. The study of these oils was performed both from a rheological and spectroscopic point of view using Fourier transform infrared spectroscopy (FTIR). The thermal degradation process consisted of repeated heating and cooling cycles at four different temperatures for 15 min performed eight times. The rheological characterization was initially performed for the fresh oils, and the results obtained were compared with those of the thermally degraded samples. For the rheological characterization, two rheological models (the Newtonian model and the power law model) were used, following which the rheological parameters were determined. At the same time, this work highlights how thermal degradation influences the rheological behavior and chemical structure of hydraulic fluids. The results obtained showed that the Newtonian model best describes the rheological behavior of the analyzed fluids. From a chemical point of view, FTIR analysis did not reveal significant changes between fresh fluids and those subjected to thermal degradation.

An estimation by simulation of the heating energy saving in the cold season due to heavily insulated exterior window shutters closed at night was performed for a low-rise to mid-rise office building in the following three major Romanian cities: Bucharest, Cluj-Napoca and Iasi. All three locations are in a wet temperate continental climate region. The studied building, whose number of floors was varied from 3 to 22, has a rectangle-shaped floor surface. The considered shutters, covering at night only the pane of the window, were assumed to be EPS panels with various thicknesses. In addition to its height more parameters related to the building were varied: its orientation, the height of the windows, the width of the building and the internal gains produced by building lights and equipment. Finally, some short evaluations were performed for a low-U glazing. For the initial glazing used in the simulation, very good potential savings were found. As the assumed heavily insulated shutters do not exist in the Romanian market, three possible design ideas for such shutters have been sketched at the end, all involving a system of guide rails.