Toward a better understanding of ferric-oxalate complex photolysis: The role of the aqueous/air interface of droplet

To mitigate hull excitation induced by propeller cavitation, our previous work proposed a single-nozzle air injection scheme based on the principle of acoustic destructive interference. Although inefficient energy consumption in a conventional air-carpet system with multiple nozzle array could be significantly reduced by the proposed method, its application was still hindered by the continuous usage of an air compressor and maintenance of the nozzle exposed to seawater. We, in this study, take advantage of the acoustic properties of rubber-like materials, which are similar to those of water. That is, a rubber layer existing at the water-to-air interface appears to be transparent in the propagation of acoustic waves. More specifically, a rubber membrane filled with air could be anticipated to act only the role of airpacking without influencing the desired acoustic phenomenon, i.e., destructive interference. Hence, the purpose of this work is to provide analytical evidence to prove that an air-filled rubber membrane is capable of replacing the previous effort of air-injection. A design strategy for tuning the frequency of destructive interference to an exciting frequency is also presented, which can be accomplished by adjusting the rubber membrane size. Finally, two experimental demonstrations conducted in a water tunnel verifies the validity of suggested scheme.

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3D dynamics of bacteria wall entrapment at a water–air interface

Soft Matter ◽

10.1039/c9sm00077a ◽

2019 ◽

Vol 15 (16) ◽

pp. 3397-3406 ◽

Cited By ~ 8

Author(s):

Silvio Bianchi ◽

Filippo Saglimbeni ◽

Giacomo Frangipane ◽

Dario Dell'Arciprete ◽

Roberto Di Leonardo

Keyword(s):

Hydrodynamic Interactions ◽

Air Interface ◽

A Cell

We determine the role of hydrodynamic interactions for a cell swimming close to an impenetrable boundary.

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Mucus Is a Key Factor in Neisseria meningitidis Commensalism

mSphere ◽

10.1128/msphere.00777-19 ◽

2019 ◽

Vol 4 (6) ◽

Author(s):

Melanie M. Callaghan ◽

Joseph P. Dillard

Keyword(s):

Neisseria Meningitidis ◽

Human Infection ◽

Content Type ◽

Host Interactions ◽

Air Interface ◽

Culture Model ◽

Key Factor ◽

Tissue Culture Model ◽

Insight Into

ABSTRACT The work presented by Audry et al. (M. Audry, C. Robbe-Masselot, J.-P. Barnier, B. Gachet, et al., mSphere 4:e00494-19, 2019, https://doi.org/10.1128/mSphere.00494-19) gives new insight into the interactions of Neisseria meningitidis and the human nasopharynx. Using an air interface tissue culture model of a polarized, mucus-secreting epithelium, Audry et al. demonstrate that N. meningitidis bacteria do not commonly invade epithelial cells. Rather, they are trapped in the mucus layer, where they are protected from dessication. In this model, meningicocci fail to elicit a pro-inflammatory immune response and show growth effects in response to another nasopharyngeal colonizer, Streptococcus mitis. These findings prompt new questions about pathobiont behaviors, the role of mucus in bacterium-host interactions, and modeling human infection.

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Oxygen Limitation Contributes to Antibiotic Tolerance of Pseudomonas aeruginosa in Biofilms

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.48.7.2659-2664.2004 ◽

2004 ◽

Vol 48 (7) ◽

pp. 2659-2664 ◽

Cited By ~ 275

Author(s):

Giorgia Borriello ◽

Erin Werner ◽

Frank Roe ◽

Aana M. Kim ◽

Garth D. Ehrlich ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Fluorescent Protein ◽

Oxygen Limitation ◽

Anaerobic Conditions ◽

Air Interface ◽

Green Fluorescent ◽

Local Oxygen

ABSTRACT The role of oxygen limitation in protecting Pseudomonas aeruginosa strains growing in biofilms from killing by antibiotics was investigated in vitro. Bacteria in mature (48-h-old) colony biofilms were poorly killed when they were exposed to tobramycin, ciprofloxacin, carbenicillin, ceftazidime, chloramphenicol, or tetracycline for 12 h. It was shown with oxygen microelectrodes that these biofilms contain large anoxic regions. Oxygen penetrated about 50 μm into the biofilms, which averaged 210 μm thick. The region of active protein synthesis was visualized by using an inducible green fluorescent protein. This zone was also limited to a narrow band , approximately 30 μm wide, adjacent to the air interface of the biofilm. The bacteria in mature biofilms exhibited a specific growth rate of only 0.02 h−1. These results show that 48-h-old colony biofilms are physiologically heterogeneous and that most of the cells in the biofilm occupy an oxygen-limited, stationary-phase state. In contrast, bacteria in 4-h-old colony biofilms were still growing, active, and susceptible to antibiotics when they were challenged in air. When 4-h-old colony biofilms were challenged under anaerobic conditions, the level of killing by antibiotics was reduced compared to that for the controls grown aerobically. Oxygen limitation could explain 70% or more of the protection afforded to 48-h-old colony biofilms for all antibiotics tested. Nitrate amendment stimulated the growth of untreated control P. aeruginosa isolates grown under anaerobic conditions but decreased the susceptibilities of the organisms to antibiotics. Local oxygen limitation and the presence of nitrate may contribute to the reduced susceptibilities of P. aeruginosa biofilms causing infections in vivo.

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Hydrophobic copolymers added with starch at the size press of a paper machine: A review of findings and likely mechanisms

BioResources ◽

10.15376/biores.16.1.bildikdal ◽

2020 ◽

Vol 16 (1) ◽

pp. 2138-2180

Author(s):

Ahsen E. Bildik Dal ◽

Martin A. Hubbe

Keyword(s):

Aqueous Solution ◽

Energy Functional ◽

Low Energy ◽

Ionic Form ◽

Paper Machine ◽

Alkyl Chains ◽

Hydrophobic Compounds ◽

Air Interface ◽

Press Equipment

This article reviews publications with the goal of understanding the role of hydrophobic copolymers added to size-press starch as a means to make paper products more resistant to penetration by aqueous fluids. The underlying technology is considered, including background related to starch, size-press equipment, and various hydrophobic copolymers and latex products that have been evaluated. The resulting hydrophobization of the paper has been reported to depend not only on the dosage of the hydrophobic additive, but also on its molecular mass and ionic form. The mechanism appears to rely on an ability of starch to serve as a temporary host for hydrophobic compounds in aqueous solution. It has been proposed that hydrophobic copolymers added with size press starch tend to migrate to the air interface during drying of the starch film, thus allowing the low-energy functional groups, such as styrene or alkyl chains, to face outwards. Further research is needed to address various mechanistic questions. There may be opportunities to further raise the performance of this type of technology as practiced within paper production factories.

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