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Physiological Mechanisms for the Action of Pulmonary Surfactant
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
In most physiological studies, the contact angle has been ignored on the basis that a clean platinum plate is perfectly wettable, when θ = 0 and cosθ = 1 in Equation 4. Anyone recording significant contact angles has often been accused of not observing proper cleanliness procedures and generally using “greasy” plates. This argument29 is fine as long as one is only using pure water, but lung surfactant is a lipid and does not all remain located at the liquid-air interface when it is introduced onto the Langmuir trough. Acting like any other surfactant, some is directly adsorbed onto the platinum surface such that the substance under study is itself the “grease” reducing the value of F in Equation 4 and, hence, producing artifactually low values of γ if θ is assumed to be zero.30 One cannot simply allow for θ because the contact angle displays hysteresis as the meniscus rises and falls on the flag, but it cannot be ignored as negligible since independent methods of measuring contact angles14 have shown values of 70° or more on flags removed from the trough during a Wilhelmy run which has produced a typical γ:A loop quoted in conventional theory (see Figure 4). The γ-axis in those plots should really be termed apparent surface tension.
Treatment of varicose veins: Current guidelines
Published in Peter Gloviczki, Michael C. Dalsing, Bo Eklöf, Fedor Lurie, Thomas W. Wakefield, Monika L. Gloviczki, Handbook of Venous and Lymphatic Disorders, 2017
Injection of a chemical into the vein to achieve endoluminal fibrosis and obstruction of the vein has been used for almost a century. Sclerotherapy lost popularity after a study from Europe demonstrated poorer clinical outcomes when sclerotherapy (liquid) was compared with surgery.21 Chemical ablation re-entered the arena with the advent of foam sclerotherapy, which has improved efficacy. Sclerosant in the form of foam is more effective for saphenous vein closure when compared to its liquid counterpart22,23 and is more readily visualized with ultrasound imaging (ultrasound-guided foam sclerotherapy). Until recently, physicians only had the option of compounding their own foam using a liquid–air mixture. Physicians began substituting carbon dioxide for air when case reports of paradoxical embolization began to surface in the literature.24
Introduction: History, biology, physics, cryogens
Published in Richard P. Usatine, Daniel L. Stulberg, Graham B. Colver, Cutaneous Cryosurgery, 2014
Richard P. Usatine, Daniel L. Stulberg, Graham B. Colver
After World War II liquid nitrogen (−196°C) became widely available and Allington used this on a swab applicator to treat some benign skin lesions, including warts, keratoses, leukoplakia, hemangiomas, and keloids. Liquid nitrogen had similar properties to liquid air and oxygen but was much safer to use. Studies comparing liquid nitrogen swabs and solid carbon dioxide showed that liquid nitrogen provided more effective heat exchange, largely due to its lower boiling point. The swab method, however, has a limited freezing capacity due to its low thermal mass and the poor conductivity between swab and skin. Zacarian and Adham attempted to overcome these limitations by applying solid copper cylinders, cooled in liquid nitrogen, directly to the skin. The improved heat exchange and thermal mass enabled them to achieve freezing to a depth of 7 mm compared with the 2 mm achieved with swabs.
Effects of dam and seqA genes on biofilm and pellicle formation in Salmonella
Published in Pathogens and Global Health, 2018
Sinem Uğur, Nefise Akçelik, Fatma Neslihan Yüksel, Neslihan Taşkale Karatuğ, Mustafa Akçelik
All wild-type and mutant strains were evaluated for their pellicle forming abilities. Physical features of pellicle (rigid, fragile and elastic), media turbidity, pellet at the bottom of the test tube and formation of ring structure between liquid-air interface were also visually evaluated after 8 days of incubation. When the properties of the pellicle formation in the liquid-air intermediate phase were examined, it was found that pellicle formation was observed in the all tested serovars of DMC2 (S. Group C1), DMC4 (S. Typhimurium), DMC11 (S. Virchow), DMC22 (S. Enteritidis) and DMC89 (S. Montevideo) (p < 0.05). The ability to form a pellicle in the dam and seqA mutants of the same serovar was lost. On the other hand, parallel to the results obtained from biofilm formation characteristics on polystyrene surface, after transferring the pBAD24 vector containing the dam and seqA genes to the dam and seqA mutants, it was determined that if these transformants were induced in the presence of 0.01% arabinose, the ability of pellicle formation was regained (p < 0.05) (Figure 4).
Extrusion-based systems for topical and transdermal drug delivery
Published in Expert Opinion on Drug Delivery, 2023
Ana Luiza Lima, Idejan P. Gross, Lívia Lira de Sá-Barreto, Tais Gratieri, Guilherme Martins Gelfuso, Marcilio Cunha-Filho
On the other hand, to produce the chitosan-based system, some modifications were applied to a standard FDM 3D printer to enable the printing of a solution of the polymer matrix. For that, a low-temperature manufacturing system was built by combining Peltier cells and liquid/air exchangers. The obtained devices present biocompatibility and cytocompatibility properties since, when placed in the skin associated human cell lines, they successfully attached, grew, and colonized the 3D structures [56]. Thereafter, the potential cell regeneration has been proven through in vivo assays on rat models with diabetes. Indeed, the 3D chitosan scaffold led to healed wounds and skin regeneration. This therapeutic response was improved compared to rats treated with a commercial product [56].
The Importance of Anatomic Configuration and Cystic Changes in Macular Hole: Predicting Surgical Success with a Different Approach
Published in Current Eye Research, 2022
Yucel Ozturk, Abdullah Ağın, Nadir Kockar, Nevzat Ay, Serhat Imamoglu, Alev Ozcelik Kose, Suleyman Kugu
Surgery was performed by the same surgeon (Y.O.) in all cases, using standard 3-port, 23-gauge pars plana vitrectomy. When a cataract was present, a combined phacovitrectomy was performed. Twenty-three-gauge trocar cannulas were placed 3.5 mm posterior to the limbus. Patients underwent PPV and internal limiting membrane peeling surgery. The posterior hyaloid was wholly detached from the retina after the core vitrectomy. The brilliant blue injection was applied to visualize the internal limiting membrane in the macular region, and the internal limiting membrane was peeled off. Liquid-air exchange was performed, and the air in the vitreous cavity was replaced with 20% sulfur hexafluoride. After the surgery, patients were advised to stay in the prone position for 1 week.