This review article covers a concise account on fludeoxyglucose (18F–FDG) synthesis and quality control procedures with emphasis on practical synthesis Currently, 18F–FDG is the most successful PET radiopharmaceutical so far. The advancement in synthesis and quality control of 18F–FDG, together with its approval by the US FDA and the availability of reimbursement, are probably the main reasons for the flourish of clinical PET over the last 20 years. 18F–FDG can be synthesised by either electrophilic fluorination or nucleophilic fluorination reaction. Nucleophilic fluorination using mannose triflate as precursor and Kryptofix or tetrabutylammonium salts (TBA) is widely used because of higher yield and shorter reaction time. The quality control requirements of 18F–FDG can be found in United States Pharmacopeia (USP), British Pharmacopeia (BP), European Pharmacopeia (EP) and the Chemistry, Manufacturing, and Controls (CMC) section from United States Food and Drug Administration (US FDA) PET draft guidance documents. Basic requirements include radionuclidic identity, radiochemical purity, chemical purity, pH, residual solvent, sterility, and bacterial endotoxin level. Some of these tests (sterility, endotoxins and radionuclidic purity) can be finished after the 18F–FDG has been released. Although USP, BP and EP do not require filter membrane integrity test, many laboratories perform this test as an indirect evident of the product sterility. It is also interesting to note that there are major differences in 18F–FDG quality requirements among USP, BP, and CMC.

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Melt blowing involves applying a jet of hot air to an extruding polymer melt and drawing the polymer stream into microfibers. This study deals with the dynamic modeling of the instabilities and related processes during melt blowing. A bead-viscoelastic element model for fiber formation simulation in the melt blowing process was proposed. Mixed Euler-Lagrange approach was adopted to derive the governing equations for modeling the fiber motion as it is being formed below a melt-blowing die. The three-dimensional paths of the fiber whipping in the melt blowing process were calculated. Predicted parameters include fiber diameter, fiber temperature, fiber stress, fiber velocity, and the amplitude of fiber whipping. The mathematical model provides a clear understanding on the mechanism of the formation of microfibers during melt blowing.

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Electrospinning and melt blowing are the most commonly used processes to produce microfibers from extruded polymer solution or melt. The present work deals with the dynamic modeling of the whipping instability and related processes during production of microfibers. A bead-viscoelastic element fiber model is employed in modeling three-dimensional paths of the fiber motion in the processes of electrospinning and melt blowing. The simulation results provide a reasonable comparison between these two processes and point out that the Coulomb force in electrospinning always has the function to sustain and increase the bending instability; while in the melt blowing process, whether the aerodynamic force increases the bending instability or not depends on several factors.