Thermoresponsive microgels at the air–water interface: the impact of the swelling state on interfacial conformation

Soft Matter ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 230-238 ◽  
Author(s):  
J. Maldonado-Valderrama ◽  
T. del Castillo-Santaella ◽  
I. Adroher-Benítez ◽  
A. Moncho-Jordá ◽  
A. Martín-Molina
Keyword(s):  
Water Interface ◽  
Temperature Responsive ◽  
Air Water Interface ◽  
The Impact

Poly(N-vinylcaprolactam) (PVCL) is a new temperature-responsive type of polymer microgel with improved biocompatibility as compared to more commonly used poly(N-isopropylacrylamide) (PNIPAM).

scholarly journals Effects of sedimentation, microgravity, hydrodynamic mixing and air–water interface on α-synuclein amyloid formation

2020 ◽  
Vol 11 (14) ◽  
pp. 3687-3693 ◽  
Author(s):  
Jiangtao Zhou ◽  
Francesco S. Ruggeri ◽  
Manuela R. Zimmermann ◽  
Georg Meisl ◽  
Giovanni Longo ◽  
...  
Keyword(s):  
Comprehensive Analysis ◽  
Aggregation Kinetics ◽  
Amyloid Formation ◽  
Water Interface ◽  
Air Water Interface ◽  
The Impact

A comprehensive analysis on the impact of sedimentation, microgravity hydrodynamic mixing and air–water interface on α-synuclein aggregation kinetics.

Adhesion of Colloids and Bacteria to Porous Media: A Critical Review

2019 ◽  
Vol 7 (4) ◽  
pp. 417-460 ◽  
Author(s):  
Runwei Li ◽  
Changfu Wei ◽  
Hefa Cheng ◽  
Gang Chen
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Bacterial Adhesion ◽  
Fate And Transport ◽  
Theoretical Models ◽  
Water Interface ◽  
Subsurface Soil ◽  
Air Water Interface ◽  
Surface Physicochemical Properties ◽  
The Impact

Adhesion of colloids and bacteria to various surfaces is important for a variety of environmental phenomena including microbial biofouling and contamination prevention. Under saturated conditions, both colloids and bacteria have the opportunity to attach to porous medium surfaces. Under water unsaturated conditions or in the presence of the air-water interface, besides the porous medium surfaces, colloids and bacteria can also attach to the air-water interface, including the air-water-solid threephase interface. The magnitudes of adhesion of colloids and bacteria are correlated to the interactions of the colloids and bacteria with the surfaces, which are a function of their surface physicochemical properties. In this review, adhesion theories are revisited and adhesion of colloids and bacteria to porous media and the air-water interface is discussed. The interaction forces are quantified using various theoretical models including the DLVO models and used to interpret related adhesion. The impact of surfactants on colloid and bacterial adhesion is also discussed. The review also includes the implementation of the adhesion theory in interpreting colloid and bacterial fate and transport in the subsurface soil.

Impact of artificial monolayer application on stored water quality at the air–water interface

2015 ◽  
Vol 72 (7) ◽  
pp. 1250-1256 ◽  
Author(s):  
P. Pittaway ◽  
V. Martínez-Alvarez ◽  
N. Hancock ◽  
B. Gallego-Elvira
Keyword(s):  
Water Quality ◽  
Oxygen Demand ◽  
Cost Effective ◽  
Subsurface Water ◽  
Water Tank ◽  
Water Interface ◽  
Field Investigations ◽  
Air Water Interface ◽  
Large Water ◽  
The Impact

Evaporation mitigation has the potential to significantly improve water use efficiency, with repeat applications of artificial monolayer formulations the most cost-effective strategy for large water storages. Field investigations of the impact of artificial monolayers on water quality have been limited by wind and wave turbulence, and beaching. Two suspended covers differing in permeability to wind and light were used to attenuate wind turbulence, to favour the maintenance of a condensed monolayer at the air/water interface of a 10 m diameter tank. An octadecanol formulation was applied twice-weekly to one of two covered tanks, while a third clean water tank remained uncovered for the 14-week duration of the trial. Microlayer and subsurface water samples were extracted once a week to distinguish impacts associated with the installation of covers, from the impact of prolonged monolayer application. The monolayer was selectively toxic to some phytoplankton, but the toxicity of hydrocarbons leaching from a replacement liner had a greater impact. Monolayer application did not increase water temperature, humified dissolved organic matter, or the biochemical oxygen demand, and did not reduce dissolved oxygen. The impact of an octadecanol monolayer on water quality and the microlayer may not be as detrimental as previously considered.

scholarly journals Ozonolysis of fatty acid monolayers at the air–water interface: organic films may persist at the surface of atmospheric aerosols

2020 ◽  
Author(s):  
Ben Woden ◽  
Max W. A. Skoda ◽  
Adam Milsom ◽  
Armando Maestro ◽  
James Tellam ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Surface Film ◽  
Rate Coefficients ◽  
Cloud Formation ◽  
Nonanoic Acid ◽  
Climate Modelling ◽  
Water Interface ◽  
Reaction Products ◽  
Air Water Interface ◽  
The Impact

Abstract. Ozonolysis of fatty acid monolayers was studied to understand the fate of organic-coated aerosols under realistic atmospheric conditions. Specifically, we investigated the effects of temperature and salinity on the degradation of oleic acid at the air–water interface and the persistence of the aged surfactant film at the surface. The presence of a residual film is of atmospheric importance, as surface monolayers affect the physical properties of the droplets and because of the role they play in cloud formation. This occurs via several effects, most notably via surface tension reduction. The interplay between atmospheric aerosol loading and the formation, nature, and persistence of clouds is a key uncertainty in climate modelling. Our data show that a residual surface film, which we suspect to be formed of nonanoic acid and a mixture of azelaic and 9-oxononanoic acids, is retained at the interface after ozonolysis at near-freezing temperatures, but not at room temperature. Given the low temperature conditions used here are atmospherically realistic, the persistence of a product film must be considered when assessing the impact of unsaturated fatty acid partitioned to the air–water interface. The presence of stable (non-oxidisable) reaction products also opens the possibility of build-up of inert monolayers during the aerosol life-cycle with potential implications for cloud formation. We also measured the kinetic behaviour of these films and found that the reactions are not significantly affected by the shift to a lower temperature with rate coefficients determined to be (2.2 ± 0.4) × 10−10 cm2 s−1 at 21 ± 1 °C, and (2.2 ± 0.2) × 10−10 cm2 s−1 at 2 ± 1 °C.

scholarly journals Impact of Engineered Carbon Nanodiamonds on the Collapse Mechanism of Model Lung Surfactant Monolayers at the Air-Water Interface

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 714
Author(s):  
Aishik Chakraborty ◽  
Amanda Hertel ◽  
Hayley Ditmars ◽  
Prajnaparamita Dhar
Keyword(s):  
Lung Surfactant ◽  
Collapse Mechanism ◽  
Water Interface ◽  
Monolayer Films ◽  
Surfactant Monolayers ◽  
Collapse Mechanisms ◽  
Lipid Mixtures ◽  
Air Water Interface ◽  
Inhaled Nanoparticles ◽  
The Impact

Understanding interactions between inhaled nanoparticles and lung surfactants (LS) present at the air-water interface in the lung, is critical to assessing the toxicity of these nanoparticles. Specifically, in this work, we assess the impact of engineered carbon nanoparticles (ECN) on the ability of healthy LS to undergo reversible collapse, which is essential for proper functioning of LS. Using a Langmuir trough, multiple compression-expansion cycles are performed to assess changes in the surface pressure vs. area isotherms with time and continuous cyclic compression-expansion. Further, theoretical analysis of the isotherms is used to calculate the ability of these lipid systems to retain material during monolayer collapse, due to interactions with ECNs. These results are complemented with fluorescence images of alterations in collapse mechanisms in these monolayer films. Four different model phospholipid systems, that mimic the major compositions of LS, are used in this study. Together, our results show that the ECN does not impact the mechanism of collapse. However, the ability to retain material at the interface during monolayer collapse, as well as re-incorporation of material after a compression-expansion cycle is altered to varying extent by ECNs and depends on the composition of the lipid mixtures.

scholarly journals Albumin displacement at the air–water interface by Tween (Polysorbate) surfactants

2020 ◽  
Vol 49 (7) ◽  
pp. 533-547 ◽  
Author(s):  
Martin Rabe ◽  
Andreas Kerth ◽  
Alfred Blume ◽  
Patrick Garidel
Keyword(s):  
Surface Pressure ◽  
Tween 80 ◽  
Lower Surface ◽  
Tween 20 ◽  
Critical Surface ◽  
Water Interface ◽  
Brewster Angle Microscopy ◽  
Protein Film ◽  
Air Water Interface ◽  
The Impact

AbstractTween (polysorbate) 20 and 80 are surfactants used for the development of parenteral protein drugs, due to their beneficial safety profile and stabilisation properties. To elucidate the mechanism by which Tween 20 and 80 stabilise proteins in aqueous solutions, either by a “direct” protein to surfactant interaction and/or by an interaction with the protein film at the air–water interface, we used spectroscopic (Infrared Reflection Absorption Spectroscopy, IRRAS) and microscopic techniques (Brewster Angle Microscopy, BAM) in combination with surface pressure measurements. To this end, the impact of both types of Tweens with regard to the displacement of the protein from the air–water interface was studied. As a model protein, human serum albumin (HSA) was used. The results for the displacement of the adsorbed HSA films by Tweens 20 and 80 can partially be understood on the basis of an orogenic displacement mechanism, which depends on the critical surface pressure of the adsorbed protein film. With increasing concentration of Tween in the sub-phase, BAM images showed the formation of different domain morphologies. IRRA-spectra supported the finding that at high protein concentration in the sub-phase, the protein film could not be completely displaced by the surfactants. Comparing the impact of both surfactants, we found that Tween 20 adsorbed faster to the protein film than Tween 80. The adsorption kinetics of both Tweens and the speed of protein displacement increased with rising surfactant concentration. Tween 80 reached significant lower surface pressures than Tween 20, which led to an incomplete displacement of the observed HSA film.

Microplastic water repellency impacts water flow and microplastic transport in soils

2021 ◽  
Author(s):  
Andreas Cramer ◽  
Pascal Benard ◽  
Anders Kaestner ◽  
Mohsen Zare ◽  
Andrea Carminati
Keyword(s):  
Porous Media ◽  
Water Flow ◽  
Capillary Rise ◽  
Water Repellency ◽  
Water Infiltration ◽  
Water Interface ◽  
Deuterated Water ◽  
X Ray ◽  
Air Water Interface ◽  
The Impact

<p>Soils are considered the largest sink of microplastic particles (MP) in terrestrial ecosystems. However, there is little knowledge on the implications of MP contaminating soils. In particular, we do not know the extent of and conditions under which MP are transported through porous media and, if they are deposited, how they affect soil hydraulic properties and soil moisture dynamics. We hypothesize that: 1) hydrophobic MP enhance soil water repellency; 2) isolated MP are displaced and transported by the air-water interface; 3) clusters of MP impede water flow and are retained in air-filled pores.</p><p>We tested these hypotheses in mixtures of MP (µm range) and sands (mm range) in a series of experiments. The Sessile Drop Method (SDM) was applied to measure the average contact angle (CA) of the mixtures for MP and model porous media in the same size range, ranging from 0 - 100 % MP content. Based on the specific surface and shape factor of MP and soil particles, the results are extrapolated to different MP and soil particle sizes. Capillary rise experiments were performed to measure the impact of MP on water infiltration. The applied MP contents of 0.35 % and 1.05 % reflect an average CA of 60° and 90° from the SDM extrapolation. Capillary rise of water and ethanol were carried out to estimate the apparent CA. Additionally and with the same MP content, we simultaneously imaged in three-dimensions the movement of deuterated water and MP during repeated drying / wetting cycles using X-Ray and Neutron tomography (at the beamline ICON, PSI). The different neutron attenuation coefficients of deuterated water and MP allows for estimating their distribution in the sand packing.</p><p>Already at MP contents of 5 % the CA measured with the SDM exhibited a steep increase and reached 59° to 81°, depending on the grain size of MP. The capillary rise experiments showed that MP reduce capillary rise. The apparent CA (43° and 53°) were smaller compared to the average CA from the SDM (60° and 90°), but the added MP increased air entrapment during capillary rise leading to a reduced saturation of the pore space (18 % and 16.5 %). Accumulation of MP at the advancing air-water interface was visible. Neutron and X-ray imaging showed at high resolution that regions with major MP content are water repellent and, are bypassed by water flow, and remain in air-filled pores.</p><p>Extrapolation of these results to soils suggests that in microregions with high MP contents, water infiltration is hindered. The low water content in these microregions might limit MP degradation due to reductions in: hydrolysis, coating of MP by e.g. dissolved organic substances, and colonization by microorganisms.</p>

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