Additive manufacturing technologies (or 3D printing) have emerged as potent tools in the creation of a diverse array of objects, promising a paradigm shift in production methodologies across industries. However, the benefits of these technologies can be diminished by the use of suboptimal parameters or inferior materials, leading to defects that significantly degrade the quality and functionality of the resulting products. An incomplete understanding of defect formation keeps under the formulation of effective preventative strategies. In light of this, our review provides a comprehensive exploration of defects that arise during the Fused Filament Fabrication (FFF)—one of the most prevalent 3D printing methods. The defects are systematically classified according to several key characteristics, including size, type, mode of occurrence, and location. Each common defect is extensively discussed, detailing its external manifestation, root causes, the impact on the properties of printed parts, and potential preventative measures. Our findings unveil the complex interplay of material properties, printing parameters, and cooling dynamics in the defect formation process. This classification holds significant practical relevance, providing a solid foundation for the development of strategies for defect minimization and quality improvement in 3D printed products. It offers valuable insights for a broad audience, including researchers exploring additive manufacturing technologies, 3D printing engineers, 3D printer operators, and quality assurance (QA) engineers involved in production quality control. Furthermore, our review delineates the path for future research in this domain. There is a crucial need for the development of advanced machine learning and artificial intelligence models that can predict defect formation based on given printing parameters and material properties. Future investigations should also focus on the discovery of novel materials and refining of printing parameters to achieve superior quality of FFF 3D printed products. This review serves as a cornerstone for these future advancements, promoting a deeper understanding of defect formation and prevention in additive manufacturing.

Additive manufacturing technologies (or 3D printing) have emerged as powerful tools for creating a diverse array of objects, promising a paradigm shift in production methodologies across industries. In chemistry, it allows the manufacturing of reactors with complex topology. However, the benefits of these technologies can be diminished by the use of suboptimal parameters or inferior materials, leading to defects that significantly degrade the quality and functionality of the resulting products. The formulation of effective preventive strategies remains hampered by an incomplete understanding of defect formation. Given this, our review provides a comprehensive exploration of defects that arise during the Fused Filament Fabrication (FFF) — one of the most prevalent 3D printing methods. The defects are systematically classified according to several key characteristics, including size, type, mode of occurrence, and location. Each common defect is discussed in detail, describing its external manifestation, root causes, the impact on the properties of printed parts, and potential preventive measures. Our findings unveil the complex interplay between material properties, printing parameters, and cooling dynamics in the defect formation process. This classification has significant practical relevance, providing a solid basis for the development of strategies to minimize defects and improve the quality of 3D printed products. It provides valuable insights for a wide audience, including researchers investigating chemical processes and additive manufacturing technologies, 3D printing engineers, 3D printer operators, and quality assurance engineers involved in production quality control. In addition, our review points the way forward for future research in this area. There is a crucial need for the development of advanced machine learning and artificial intelligence models that can predict defect formation based on given printing parameters and material properties. Future investigations should also focus on the discovery of novel materials and refining of printing parameters to achieve superior quality of FFF 3D printed products. This is the first review on defect analysis, classification, and prevention methods in 3D printing. This review serves as a cornerstone for these future advances, promoting a deeper understanding of defect formation and prevention in additive manufacturing. The bibliography includes 180 references .

The development of new drugs is accelerated by rapid access to functionalized and D-labeled molecules with improved activity and pharmacokinetic profiles. Diverse synthetic procedures often involve the usage of gaseous reagents, which can be a difficult task due to the requirement of a dedicated laboratory setup. Here, we developed a special reactor for the on-demand production of gases actively utilized in organic synthesis (C₂H₂, H₂, C₂D₂, D₂, and CO₂) that completely eliminates the need for high-pressure equipment and allows for integrating gas generation into advanced laboratory practice. The reactor was developed by computer-aided design and manufactured using a conventional 3D printer with polypropylene and nylon filled with carbon fibers as materials. The implementation of the reactor was demonstrated in representative reactions with acetylene, such as atom-economic nucleophilic addition (conversions of 19–99%) and nickel-catalyzed S-functionalization (yields 74–99%). One of the most important advantages of the reactor is the ability to generate deuterated acetylene (C₂D₂) and deuterium gas (D₂), which was used for highly significant, atom-economic and cost-efficient deuterium labeling of S,O-vinyl derivatives (yield 68–94%). Successful examples of their use in organic synthesis are provided to synthesize building blocks of heteroatom-functionalized and D-labeled biologically active organic molecules.

In the present study, chitosan was included in the pectin ionotropic gel to improve its mechanical and bioadhesive properties. Pectin–chitosan gels P–Ch0, P–Ch1, P–Ch2, and P–Ch3 of chitosan weight fractions of 0.00, 0.25, 0.50, and 0.75 were prepared and characterized by dynamic rheological tests, penetration tests, and serosal adhesion ex vivo assays. The storage modulus (G′) and loss modulus (G″) values, gel hardness, and elasticity of P–Ch1 were significantly higher than those of P–Ch0 gel. However, a further increase in the content of chitosan in the gel significantly reduced these parameters. The inclusion of chitosan into the pectin gel led to a decrease in weight and an increase in hardness during incubation in Hanks’ solution at pH 5.0, 7.4, and 8.0. The adhesion of P–Ch1 and P–Ch2 to rat intestinal serosa ex vivo was 1.3 and 1.7 times stronger, whereas that of P–Ch3 was similar to that of a P–Ch0 gel. Pre-incubation in Hanks’ solution at pH 5.0 and 7.4 reduced the adhesivity of gels; however, the adhesivity of P–Ch1 and P–Ch2 exceeded that of P–Ch0 and P–Ch3. Thus, serosal adhesion combined with higher mechanical stability in a wide pH range appeared to be advantages of the inclusion of chitosan into pectin gel.

A comparative study of structures, stability and energetic performance of ammonium and hydrazinium salts of 4H-[1,2,3]triazolo[4,5-c][1,2,5]oxadiazole (triazolofurazan, TF) as well as its N-oxide and N-nitroimide was performed.