RESUMEN
Lubricant formulations are filtered to remove deleterious particulate matter. An unintended consequence of this important process is the detrimental effect of fine filtration on the foaming performance of lubricants with antifoam additives. Here we outline a method to study this phenomenon in detail by probing the coalescence stability of single bubbles in filtered antifoam laden lubricants. Initially, we establish the validity of Garrett's hypothesis for the tested antifoam laden lubricants. Subsequently, we show that the bubble stability in filtered lubricants are positively correlated to the number of filtration cycles - with the most dramatic changes in bubble stability accompanying the initial few cycles of filtration. Further, we show that post filtration, the stability of bubbles in lubricants is inversely correlated to the pore size of the filter and the volume fraction of antifoam in the lubricant prior to filtration. The results also reveal that in the presence of antifoam additives, the bubble coalescence times span multiple Rayleigh distributions. We also provide visual evidence that shows the tested antifoams employ a bridging-stretching mechanism to rupture non-aqueous foams. Finally, a simple probabilistic model is introduced that helps in analyzing the distribution of coalescence times of single bubbles to obtain insights into the volume fraction of antifoams in the lubricant. We believe these results are valuable in guiding the design of lubricants with robust and superior foaming performance.
RESUMEN
Foaming in liquids is ubiquitous in nature. Whereas the mechanism of foaming in aqueous systems has been thoroughly studied, nonaqueous systems have not enjoyed the same level of examination. Here we study the mechanism of foaming in a widely used class of nonaqueous liquids: lubricant base oils. Using a newly developed experimental technique, we show that the stability of lubricant foams can be evaluated at the level of single bubbles. The results obtained with this single-bubble technique indicate that solutocapillary flows are central to lubricant foam stabilization. These solutocapillary flows are shown to originate from the differential evaporation of multicomponent lubricants-an unexpected result given the low volatility of nonaqueous liquids. Further, we show that mixing of some combinations of different lubricant base oils, a common practice in the industry, exacerbates solutocapillary flows and hence leads to increased foaming.
RESUMEN
OBJECTIVE: Description of a new neurovascular island flap derived from the infrahyoid muscles to reconstruct a total tongue or large defects of the tongue base. The surgical technique, anatomic findings, and the postoperative function tests with the patients' outcome are described. Eleven patients had tongue cancer, 5 at a T2 stage, 3 at a T3 stage, and 3 at a T4 stage. Four patients underwent total glossectomy, 3 patients underwent hemiglossectomy, and in 2 patients a half and in another 2 patients a quarter of the tongue base were resected. The tongue of the patients who underwent total glossectomy has been reconstructed with the infrahyoid myofascial neurovascular flap from both sides of the neck; in all the other patients this new flap has only been taken from one side of the neck. In one patient a glossectomy had to be combined with a laryngectomy. In 10 patients the tracheostoma could be closed in 4 weeks after the operation, and all patients could eat an oral diet. Electromyography showed voluntary innervation of the reconstructed tongues. With the neurovascular infrahyoid flap, defects of the tongue base can be reconstructed successfully after partial resections or total glossectomies. The main advantage is the voluntary innervation of this flap by means of the ansa cervicalis and the prevention of scarring and atrophy of the reconstructed tongue.