Search

With growing concerns about energy and environmental issues, much research attention has been focused on manufacturing activities that consume significant amounts of energy and influence the environment. In the manufacturing field, additive manufacturing (AM) is a new production technology that can process complex parts and has high material utilization, which also has the problem of excessive energy consumption and has raised concern. However, the existing research primarily focuses on the process of AM energy consumption and its impact on the environment; the energy consumption distribution of AM equipment is still lacking. This study proposes an analytical method for addressing the energy consumption distribution of AM equipment by classifying the equipment into different energy units. In particular, the energy consumption and energy distribution of different types of AM equipment including fused deposition modeling (FDM), stereo lithography apparatus, and selective laser melting are discussed. Then, the energy consumption distribution characteristics of the three different AM equipment are investigated by machining a conventional structure using the proposed energy consumption quantification method based on energy units. The results show that the proposed method can effectively and quickly predict the energy consumption of AM equipment. Based on the energy consumption distribution method, to improve the process energy efficiency, a process optimization method considering energy consumption and forming quality is proposed to obtain the optimal process parameters of FDM. This method can provide support for energy consumption prediction and energy efficiency improvement of AM.

Additive manufacturing (AM) is a novel manufacturing technology that can create highly customized products with more complex geometries than traditional techniques. Despite its significant advantages, including the freedom of design, mass customization, and ability to produce complex structures, AM consumes a large amount of energy and incurs high costs. In addition, AM suffers from long production cycles and low production efficiency in the large-scale manufacturing of metal structures. This study offers a review of the existing literature focused on metal AM technology. To avoid the shortcomings of AM and highlight its benefits, which are widely used for manufacturing in combination with casting. The current combination application of AM and casting is reviewed to provide solutions to the problem of manufacturing large metal components from the perspective of the use of different AM technology and quality control in casting. However, such integration is insufficient for producing large castings with complex shapes, structures, or multiple features. Therefore, a novel method for integrating AM into casting to enable the manufacture of large scale metal parts with complex shapes is introduced as a topic for possible future research. This method divides complex castings with multiple features into an AM processing part and the casting substrate. The complex features were processed by AM on the fabricated casting substrate. This study provides a review of the application of AM into casting and presents a novel idea for the integration application of AM and other processes. This promising method has significant value for future study.

Cyclooxygenase (COX)-dependent production of prostaglandins (PGs) is known to play important roles in tumorigenesis. PGD2 has recently emerged as a key regulator of tumor- and inflammation-associated functions. Here we show that mesenchymal stromal cells (MSCs) from patients with acute myeloid leukemia (AML) or normal MSCs overexpressing COX2 promote proliferation of co-cultured hematopoietic stem and progenitor cells (HSPCs), which can be prevented by treatment with COX2 knockdown or TM30089, a specific antagonist of the PGD2 receptor CRTH2. Mechanistically, we demonstrate that PGD2-CRTH2 signaling acts directly on type 2 innate lymphoid cells (ILC2s), potentiating their expansion and driving them to produce Interleukin-5 (IL-5) and IL-13. Furthermore, IL-5 but not IL-13 expands CD4+CD25+IL5Rα+ T regulatory cells (Tregs) and promotes HSPC proliferation. Disruption of the PGD2-activated ILC2-Treg axis by specifically blocking the PGD2 receptor CRTH2 or IL-5 impedes proliferation of normal and malignant HSPCs. Conversely, co-transfer of CD4+CD25+IL5Rα+ Tregs promotes malignant HSPC proliferation and accelerates leukemia development in xenotransplanted mice. Collectively, these results indicate that the mesenchymal source of PGD2 promotes proliferation of normal and malignant HSPCs through activation of the ILC2-Treg axis. These findings also suggest that this novel PGD2-activated ILC2-Treg axis may be a valuable therapeutic target for cancer and inflammation-associated diseases.

Additive manufacturing (AM) technologies, such as direct laser and selective laser melting (SLM) manufacturing, allow the fabrication of functional products with high added value. This paper proposes an emergy-based method for evaluating the environmental impact and economic cost of the SLM manufacturing process while considering the environmental flows (materials, energy, and wastes) and economic factors (time, costs, and quality). By analyzing the emergy flows in an SLM system, sustainable evaluation indexes are developed to estimate its sustainability level. Then, the method is applied to analyze the environmental impact and economic cost of the SLM of a part. The results show that the cost of the process for a single part is high, the net emergy yield ratio of the SLM system is low, and its environmental load rate is very high. The sustainability indexes of the system indicated a high environmental impact and low production efficiency. However, the waste emergy output ratio of the system was very low, which reflected the near-net-shape characteristics of SLM, indicating a high sustainability potential. The results of this study are expected to contribute to increased sustainability and optimization of SLM.