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Fluid Bed Processing
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
These nozzles are available as a single-port or multiport design. Generally, the single-port nozzles are adequate up to 100-kg batch, but for larger-size batches, multiport nozzles such as either three-port or six-port (Figure 10.7a) nozzle, are required. When these nozzles are air-atomized, the spray undergoes three distinct phases. In the first, the compressed air (gas) expands, essentially adiabatically, from the high pressure at the nozzle to that of the fluid bed chamber. The gas undergoes a Joule-Thomson effect, and its temperature falls. In the second, the liquid forms into discrete drops. During this atomization, the liquid’s specific surface area usually increases 1000 times. In the third, the drops travel after being formed, until they become completely dry or impinge on the product particles. During this phase, the solvent evaporates, and the diameter of the drops decreases. The energy required to form a drop is the product of the surface tension and the new surface area. About 0.1 cal/g is needed to subdivide 1 g of water into 1 μm droplets. The air pressure required to atomize the binder liquid is set using a pressure regulator. The spray pattern and spray angle are adjusted by adjusting the air cap.
Supercritical Fluid Manufacture
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Ana Aguiar-Ricardo, Eunice Costa
Depressurization of an expanded liquid organic solution technique was introduced by Ventosa and co-workers (2001) and Ventosa et al. (2003). Herein, after the solubilization of a compressed gas such as CO2 in an organic solution of the target substance, the solution is expanded into a precipitator at ambient pressure, leading to a sudden decrease in temperature as a consequence of the Joule-Thomson effect, followed by supersaturation and precipitation of the target substance. Similarly to anti-solvent techniques, it has been applied to crystallization, but unlike GAS, the temperature and pressure parameters are set so that the compressed CO2 acts as a co-solvent to the organic solution of the target substance (Ventosa et al. 2003). There are only a few examples on the application of DELOS that are not particularly relevant for inhalation applications, given the low particle sizes.
Rhegmatogenous retinal detachment
Published in Thomas H. Williamson, Vitreoretinal Disorders in Primary Care, 2017
Cryotherapy employs the Joule–Thomson effect, whereby the expansion of certain gases, such as nitrous oxide or carbon dioxide, results in a reduction in temperature. The gas is compressed and then released through a small hole in a cryotherapy instrument tip, causing a rapid expansion of the gas and reduction in the temperature. Cryotherapy has the advantage that it can be applied from the outside of the eye. The freeze damages the internal layers, causing scar formation.
Applications of cryobiopsy in airway, pleural, and parenchymal disease
Published in Expert Review of Respiratory Medicine, 2022
Andrew DeMaio, Jeffrey Thiboutot, Lonny Yarmus
Cooling of the tip of the cryoprobe is mediated by the Joule-Thomson effect, which dictates that a liquefied gas (cryogen) cools rapidly as it expands through an orifice. In thoracic disease, cryoprobes were initially exclusively used for therapeutic purposes, specifically for destruction of neoplastic tissue that was not amenable to surgical resection. Early cryoprobes were rigid instruments that could not be passed through the working channel of a flexible bronchoscope. To access the airways, the cryoprobe was passed through a rigid bronchoscope, positioned adjacent to a tumor, and repeated freeze-thaw cycles were applied. The neoplastic tissue was destroyed by multiple mechanisms, with early injury due to crystallization of cellular structures and late injury due to vascular and potentially immunologic effects [9]. Repeat bronchoscopies were often needed to debride necrotic tissue and repeat cryotherapy. Benefits were mainly palliative and primarily used for the treatment of airway obstruction, but were also investigated later for curative treatment of early-stage cancers [10,11]. Some bronchoscopists used cryotherapy prior to biopsy to minimize bleeding, especially in the case of vascular endobronchial lesions [12].
Percutaneous cryoneurolysis for acute pain management: current status and future prospects
Published in Expert Review of Medical Devices, 2021
John J. Finneran IV, Brian M. Ilfeld
Cryoanalgesia, broadly defined as the use of cold temperature to treat pain, is an analgesic modality that dates to ancient Egypt [7]. For much of its history, cryoanalgesia relied on ice, usually in the form of snow [8]. Modern cryoanalgesic devices utilize a closed system in which a pressurized gas, usually nitrous oxide, flows down a tube contained within the cryoneurolysis probe/cannula to a low-pressure closed end before being vented back along the length of the probe and out through the machine. As the gas enters the low-pressure chamber at the tip of the probe, the pressure drops and a corresponding volume expansion results in a precipitous decline in temperature. This phenomenon, first described by James Prescott Joule and William Thomson in 1852, is known as the Joule-Thomson effect [9]. Importantly, neither the gas nor any other substance is injected into the patient. As the temperature of the probe drops, an ‘ice ball’ encompassing tissue forms around its tip (Figure 1), resulting in a reversible axonal injury and analgesia in the distribution of the treated nerve [10]. This reversible axonal injury and associated analgesia is termed cryoneurolysis[9]. Cryoneurolysis has been employed for acute and chronic pain as both an open surgical procedure and, more recently, a percutaneous ultrasound guided procedure. This review focuses primarily on ultrasound-guided percutaneous cryoneurolysis for acute pain (Table 1).
Image-guided lung metastasis ablation: a literature review
Published in International Journal of Hyperthermia, 2019
Clara Prud’homme, Frederic Deschamps, Benjamin Moulin, Antoine Hakime, Marc Al-Ahmar, Salma Moalla, Charles Roux, Christophe Teriitehau, Thierry de Baere, Lambros Tselikas
Cryotherapy kills tumor cells through a complex combination of different mechanisms produced by tissue freezing and thawing (Figure 3). The principle is based on the Joule–Thomson effect. The ablation process consists of successive freezing-thawing cycles and induces cell death by protein denaturation, membrane disruption, and microvascular thrombosis [24–27].