Dry oil powders and oil foams stabilised by fluorinated clay platelet particles

A series of platelet sericite particles coated to different extents with a fluorinating agent has been characterised and their behaviour in mixtures with air and oil studied. The material which forms by vigorous shaking depends on both the surface tension of the oil and the surface energy of the particles which control their degree of wetting. Oil dispersions are formed in liquids of relatively low tension (<22 mN m−1), e.g. hexane and cyclomethicone, for all particles. Particle-stabilised air-in-oil foams form in liquids of higher tension, e.g. dodecane and phenyl silicone, where the advancing three-phase contact angle θ, measured on a planar substrate composed of the particles into the liquid, lies between ca. 65° and 120°. For oils of tension above 27 mN m−1 like squalane and liquid paraffin with particles for which θ > 70°, we have discovered that dry oil powders in which oil drops stabilised by particles dispersed in air (oil-in-air) can be prepared by gentle mixing up to a critical oil : particle ratio (COPR) and do not leak oil. These powders, containing up to 80 wt% oil, release the encapsulated oil when sheared on a substrate. For many of the systems forming oil powders, stable liquid oil marbles can also be prepared. Above the COPR, catastrophic phase inversion occurs yielding an ultra-stable air-in-oil foam. We thus demonstrate the ability to disperse oil drops or air bubbles coated with particles within novel materials

Emulsions stabilized with polyelectrolyte complexes prepared from a mixture of a weak and a strong polyelectrolyte

The possibility of stabilizing emulsions with polyelectrolyte complexes (PEC) obtained from the interaction of two non-surface-active oppositely charged polyelectrolytes (PEL) is described. Poly(allylamine hydrochloride) (PAH) and poly(4-styrene sulfonate) sodium salt are selected as the weak cationic and the strong anionic polyelectrolyte, respectively. Aqueous polymer mixtures are investigated by light scattering to determine the size of the complexes and whether precipitation or complex coacervation occurs. The effects of PEL mixing ratio, pH, and PEL concentration are studied in detail. By increasing the pH, the transition precipitate-precipitate/coacervate-coacervate-polymer solution is observed. At low pH, both PEL are fully ionized and therefore precipitates (soft particles) arise as a result of strong electrostatic interactions. By increasing the pH, the degree of ionization of PAH decreases and weak electrostatic interactions ensue, supporting the formation of coacervate droplets. The most stable oil-in-water emulsions are prepared from aqueous mixtures around charge neutralization. Although emulsions can be prepared from coacervate droplet dispersions, their coalescence stability is worse than those stabilized by soft PEC particles. By increasing the PEL concentration, the average droplet diameter decreases and the fraction of cream in the emulsion increases for emulsions prepared with PEC particles, following the limited coalescence model. However, at high concentrations, emulsion stability is slightly worse probably due to extensive aggregation of the particles. Viscous high internal phase emulsions can be prepared at low pH in which oil droplets are deformed. Here, PEC particles are detected only at the oil-water interface. At lower oil content, excess particles form a network in the aqueous phase aiding emulsion stability to coalescence

Emulsion stabilisation by complexes of oppositely charged synthetic polyelectrolytes

We investigate the possibility of stabilising oil-water emulsions from the polyelectrolyte complexes (PEC) obtained in mixtures of a strong cationic polyelectrolyte (poly(diallyldimethylammonium chloride), PDADMAC) and a weak anionic one (poly(acrylic acid) sodium salt, PAANa). Unlike other previous work however, both polyelectrolytes (PEL) are chosen as they are completely water-soluble and possess no surface activity when present alone over nearly all the pH range. In water, the effects of PEL concentration, PEL mixing ratio and pH on the formation of PEC are studied in detail. At low pH where the anionic PEL is uncharged, complex coacervation occurs in which droplets rich in both polymers are dispersed in water. At intermediate pH, the PEC comprise a mixture of coacervate droplets and solid particles. At high pH where the anionic PEL is significantly charged, only complex coacervation is observed. On addition of dodecane followed by homogenisation, no stable emulsions arose from dispersions containing solid particle PEC due to either the large precursor particle aggregates or their inherent hydrophilicity. By contrast, oil-in-water emulsions stable to coalescence could be prepared from coacervate dispersions. We discuss the feasibility of the coacervate phase spreading at the oil-water interface in terms of the relevant spreading coefficients and compare the predictions with experiment for a range of oils. We encounter oils whose drops become engulfed by the coacervate phase as well as oils where no engulfing occurs

新規なエマルションを創製するスメクタイト化合物の増粘・乳化特性とその機構解明

東京理科大学201

Novel stabilisation of emulsions by soft particles: polyelectrolyte complexes

We put forward the concept of a novel particle stabiliser of oil-water emulsions being the polyelectrolyte complex (PEC) formed between oppositely charged water-soluble polymers, in cases where either polymer alone is incapable of stabilising an emulsion. Using poly(4-styrene sulfonate) sodium salt, PSSNa and poly(diallyldimethylammonium chloride), PDADMAC, of low polydispersity and similar molecular mass, we correlate the behaviour of their mixtures in water with that of emulsions after addition of oil. In aqueous mixtures, spherical particles of diameter between 100 and 150 nm are formed through electrostatic interactions between charged polymer chains. Around equal mole fractions of the two polymers, the zeta potential of particles reverses in sign and emulsions of oil-in-water (o/w) for a range of oils can be prepared which are the most stable to coalescence and creaming. Effects of PEC concentration and oil:water ratio have been examined. All emulsions are o/w and stability is achieved by close-packed particle layers at drop interfaces and particle aggregation in the continuous phase. Increasing the salt concentration initially causes destabilisation of the aqueous particle dispersion due to particle aggregation followed by dissolution of particles at high concentrations; the corresponding emulsions change from being stable to completely unstable and are then re-stabilised due to adsorption of uncharged individual polymer molecules

A CASE OF CORONAVIRUS DISEASE 2019 COMPLICATED BY VENTILATORASSOCIATED PNEUMONIA, LUNG ABSCESS, AND STAPHYLOCOCCUS AUREUS BACTEREMIA

Complications of healthcare-associated infections have been reported in patients with coronavirus disease 2019 (COVID-19). We encountered a case of ventilator-associated pneumonia and lung abscess, complicated with Staphylococcus aureus bacteremia and multiple abscesses, in a patient with COVID-19. Streptococci and anaerobes were cultured from the sputum, which was considered to be the causative organism of the lung abscess. In the management of severe COVID-19, care should be taken to prevent complications of healthcare-associated infections; when secondary respiratory tract infections are suspected, the presence of lung abscess and anaerobic culture should be considered

Regulation of hepatocyte growth factor by basal and stimulated macrophages in women with endometriosis

Background: The different macromolecules as secreted by macrophages (M ) in the pelvic environment are believed to enhance the growth of endometriosis. However, the possible mediator that stimulates M for the production of different growth factors is not well described. Therefore, we investigated the possible production of hepatocyte growth factor (HGF) by the basal and lipopolysaccharide (LPS)-stimulated M derived from women with or without endometriosis. Methods: Using primary culture and 4-well chamber slides, adherent M immunoreactive to CD68 were isolated from the peritoneal fluid (PF) of 20 infertile women with endometriosis and 12 women without endometriosis. The proliferation of basal and LPS-treated M was investigated by the dimethylthiazole tetrazolioum bromide (MTT) assay. The production of HGF in the culture media of basal and LPS-stimulated M was examined by enyme-linked immunosorbent assay. The expression of mRNA for HGF and its receptor, c-Met, in the M was investigated by RT-PCR. The effect of HGF on the growth of endometrial cells and M was analysed by bromodeoxyuridine (BrdU) incorporation. Results: A >100 % increase in the proliferation of peritoneal M derived from women with endometriosis, and particularly of those harbouring dominant red lesions, was observed after treatment with LPS (P < 0.05). A 4- and 3-fold increase in the production of HGF was observed by the LPS-treated M derived from women with stage I-II endometriosis and stage III-IV endometriosis, respectively, when compared with non-LPS-treated M (P < 0.001). At the transcriptional level, we found a 5-fold increase in HGF mRNA expression in LPS-treated M versus basal M in women with endometriosis (P < 0.001). The BrdU incorporation study indicates that 10-100 ng/ml of HGF enhanced the growth of endometrial epithelial cells, stroma and M (?50% increase) derived from women with endometriosis (all P < 0.05). Conclusion: LPS could be an inflammatory mediator of macrophage stimulation in the pelvic microenvironment. Besides mesenchymal cells, HGF is also produced by peritoneal M and is possibly involved in the growth of endometriosis

Two cases of Taeniasis Infection.

We report two cases of taeniasis caused by tapeworm infection. The first was a Japanese female, 23 years old, who had a history of eating raw meat during a visit to Thailand. She was referred to our hospital with a history of passing proglottids in feces. Taenia saginata or T. asiatica was suspected based on the proglottid morphologic features in addition to supportive information regarding her travel and dietary history. The patient was given praziquantel and the tapeworm was excreted. The second was a 35-year-old Thai male who had lived in Japan since 2000 and not left the country since that time. He had consumed beef cooked in the so-called yakiniku style and also sometimes raw, because of nostalgia for that Thai custom. The patient passed proglottids several times and then came to us. The proglottids were compatible with those of T. saginata. Praziquantel was prescribed and the tapeworm was excreted. In both cases, mitochondrial DNA analysis identified the worm species as T. saginata. Since morphological discrimination of three human-infecting Taenia species, T. saginata, T. solium, and T. asiatica, is not always possible, it is necessary to employ DNA analysis for diagnosis of taeniasis to confirm the worm species