A Narrative Review of Cell-Based Approaches for Cranial Bone Regeneration

Current cranial repair techniques combine the use of autologous bone grafts and biomaterials. In addition to their association with harvesting morbidity, autografts are often limited by insufficient quantity of bone stock. Biomaterials lead to better outcomes, but their effectiveness is often compromised by the unpredictable lack of integration and structural failure. Bone tissue engineering offers the promising alternative of generating constructs composed of instructive biomaterials including cells or cell-secreted products, which could enhance the outcome of reconstructive treatments. This review focuses on cell-based approaches with potential to regenerate calvarial bone defects, including human studies and preclinical research. Further, we discuss strategies to deliver extracellular matrix, conditioned media and extracellular vesicles derived from cell cultures. Recent advances in 3D printing and bioprinting techniques that appear to be promising for cranial reconstruction are also discussed. Finally, we review cell-based gene therapy approaches, covering both unregulated and regulated gene switches that can create spatiotemporal patterns of transgenic therapeutic molecules. In summary, this review provides an overview of the current developments in cell-based strategies with potential to enhance the surgical armamentarium for regenerating cranial vault defects.

Pipeline Leak Detection and Estimation Using Fuzzy PID Observer

A pipe is a ubiquitous product in the industries that is used to convey liquids, gases, or solids suspended in a liquid, e.g., a slurry, from one location to another. Both internal and external cracking can result in structural failure of the industrial piping system and possibly decrease the service life of the equipment. The chaos and complexity associated with the uncertain behaviour inherent in pipeline systems lead to difficulty in detection and localisation of leaks in real time. The timely detection of leakage is important in order to reduce the loss rate and serious environmental consequences. The objective of this paper is to propose a new leak detection method based on an autoregressive with exogenous input (ARX) Laguerre fuzzy proportional-integral-derivative (PID) observation system. The objective of this paper is to propose a new leak detection method based on an autoregressive with exogenous input (ARX) Laguerre fuzzy proportional-integral-derivative (PID) observation system. In this work, the ARX–Laguerre model has been used to generate better performance in the presence of uncertainty. According to the results, the proposed technique can detect leaks accurately and effectively.

Self-healing mortar using different types, content, and concentrations of bacteria to repair cracks.

The creation of cracks, which are the most common cause of structural failure, has a significant impact on the structure's strength and durability. As a result, effective repair and maintenance are vital and unavoidable for treating any of these issues. Self-healing mortar holds promising benefits for reducing the cost of repair as cracks are autonomously repaired without any human intervention. This study investigated the effect of bacteria type, bacteria content, bacteria concentration, and nutrient type on the properties of the self-healing mortar. Three types of bacteria, Bacillus sphaericus, Bacillus Megaterium, and Bacillus subtilis encapsulated in calcium alginate beads, were introduced into the mortar. Two concentrations of bacteria, 2× 108 and 2× 109 Colony Forming Units per milliliter, and different percentages of bacteria of cement weight were selected for the study. In addition, calcium lactate and calcium acetate were used at 0.5% of cement weight as nutrition for bacteria. Tests were performed for compressive strength, bending strength, SEM, EDX, and TGA/DTG. The results show a significant development in the mechanical behaviour of mortar, especially with Bacillus Megaterium using a 2.5% bacterial proportion with a concentration 2× 109 CFU/ml. This can be related to the filling of voids and cracks in microbial mortar by calcite, which was confirmed by SEM and EDX.

Computational Analysis of the Forces Distribution in a Metal Frame Structure Taking into Account Plastic Deformations of the Material

Постановка задачи. С целью снижения материалоемкости строительных конструкций нормативные документы рекомендуют учитывать пластические свойства стали в прочностных расчетах. Это требует развития соответствующих методов расчета с применением современного программного обеспечения. Результаты. Усовершенствована методика расчета плоского стального рамного каркаса на статическую нагрузку на основе принципа предельного равновесия с применением программно-вычислительного комплекса «ЛИРА». Исследован поэтапный характер разрушения конструкции при воздействии сверхнормативных нагрузок. Выводы. Показано, что применение пошагового метода нагружения позволяет моделировать поведение конструкции в ходе увеличения нагрузки. Проведенные исследования позволяют давать верхнюю оценку максимально возможной нагрузки, возникающей в исключительных условиях эксплуатации. Statement of the problem. In order to reduce the material consumption of building structures, in regulatory documents it is recommend that the plastic properties of steel in strength calculations are taken into account. This requires the development of appropriate calculation methods by means of modern software. Results. The method of calculating a flat steel frame structure for static load based on the principle of limiting equilibrium using the design-computational complex LIRA has been improved. The gradual nature of structural failure under the influence of excessive loads is studied. Conclusions. It is shown that the application of the step-by-step loading method makes it possible to model the behavior of the structure during an increase in load. The studies allow us to provide an upper estimation of the maximum possible load that occurs under exceptional operating conditions.

Structural Monitoring of a Large Archaeological Wooden Structure in Real Time, Post PEG Treatment

Large archaeological wooden structures are potentially at risk of structural failure through deformation and cracking over time if they are left untreated and their structural health is not maintained. This could be in part due to, for example, the shrinkage of waterlogged wood as it dries, or time-dependent creep processes. These dimensional changes are accompanied by associated stresses. However, there are few studies analysing the movement of large wooden structures in real time as they dry, particularly after their conservation treatment. This paper follows the structural monitoring of the Mary Rose from after the conservation treatment, where it was sprayed with polyethylene glycol, through to the ship’s air-drying process and beyond to assess the effects that drying has had on the displacement of the timbers. A laser-based target system was used to collect displacement data between 2013 and 2020 and the data showed a significant slowing of displacement as the drying reached an equilibrium.

WHY YACHT RUDDERS BREAK

For most sailing yachts, losing a rudder is probably the most catastrophic structural failure other than losing the keel. Rudder failure happens with distressing regularity. This paper examines the hypothesis that the underlying reason is design failure. There are many qualitative decisions to be taken in the design calculation process. Example calculations are presented which show that the maximum rudder force generated in steady state conditions is easily underestimated. For a typical spade rudder of a typical modern production sailing yacht, the normal rudder force should be calculated using a boat speed of at least 125% hull speed, and a force coefficient of at least 1.3. Care must be taken in selecting an appropriate value for the allowable stress of the material used for the stock.

Numerical analysis of shear interaction of an underground structure with soil

A soil layer behaviour under the shear interaction of an underground structure with soil is studied. Structural failure is considered under conditions of strained soil, and complete cohesion is assumed at the underground structure-soil contact boundary. The Finite Difference Method is used to numerically investigate the process of the structure-soil shear interaction under consideration. The main attention is paid to the adequacy of the conditions of soil-structure interaction, and to the strain state of the near-contact soil layer around the underground structure. The results are plotted and analysed. From the results obtained, the existence of a near-contact soil layer is shown; the use of the condition of complete cohesion is justified considering the structural failure of soil under conditions of complex interaction; the possibility to determine the thickness of the near-contact soil layer and of the layers with the respective degrees of structural failure is shown.

Final design of the ITER bolometer first plasma component: cable installation template

The ITER bolometer cable installation template is a first plasma component which main function is to provide a temporary fixation of the mineral insulated cables and to protect them through first plasma operation inside the vacuum vessel until the final bolometer cameras are installed in the second assembly phase. In this paper, the final design of the cable installation template will be presented, the assembly procedures and important functional design details in order to be compliant with its interfaces, the vacuum vessel, the flux loops, the electrical services, the first plasma components and the assembly. Requirements that drive the design will be explained, along with the technical solutions chosen to fulfill them. Important sub-components will be presented in more detail, such as the boss fixation, which will compensate geometrical uncertainties of the as-built boss positioning, as well as the mineral insulated cable holder, which will prepare the electrical termination and facilitate the installation of final vacuum vessel cameras during the second assembly phase of ITER. Additionally, the step-by-step assembly plan agreed with the team of ITER machine assembly and tooling will be described. A custom developed boss welding tool will be described as well. The system load specifications applicable for this first plasma component will be presented as well and an overview of the structural integrity analysis report will be given. It will be shown that most loads on the component are very limited and there is no risk of structural failure or loss of relevant system functions. The paper concludes with a summary of the work and an overview of the procurement and delivery status to ITER.